tssN:0308 -2237

CV NEWS LETTEtrI ?7col'rite tochniqu€ du coFPrrs vitFeaFurrl

ICCFIGIM 13VIA EtI SAN MICHELE FICIMA e2 JUIN 7A

THIS ISsiUE CONTAINS ARTICLES clNIOIESE NIJMMER ENTHALT FG,LGENEIE CIEITRAGiE:CE NUMERGI CCINTIENT E'EEI AEI?ICLEE SUR:

1 generalitiesT.L PROCEEDINGS OF Ti{E Loth CoLLOQUIUM 0F I}IL

CV}'A, HELD IN STUTTGART AND FREIBURG-I-BR.(1s77)

The German cormittee of the Cor"pus has now

published the Pnoceedings of the Colloquium'held fnorn 22nd to 28th May f977 (Akten deslO international-en Co]Loquiuns des Conpus

cefY-botnd booklet, measu:ning 210 x I50 nun, andhaving a bl-ue coven. The 72 pages of theProceedings contain abstnacts of all thecomtnunications and discussions, i.e.,

Rudi ge r Be ck srnarur r trArchi tektu:,"b e din gtewandiungan-in ilen deutschen Gfasnslerei des13. ,Jahrhundertsil (Changes in l3th-centurS'glass painting introduced by architecturalconsidenations), Pages i-9-20.

Kar.l--Joachim Mqeqcker?" |rFnUhe thUningiseh-sactrs-i s ctre G lasmale re ien rur d ih:: Ve r:h iif tniszu SkuLptur rnd Mal-ereitt (Eanfy thu:ringian-Saxon gLass painting and their dependence onscuJ-ptur€ and paintings)n page 21.

UIf-Dietrich Korn. rrDas Iohner Jesse-Fensterund die Soester Wandma]enei um 1250" (lheLohne:r Jesse window and the Soest wall paintingsof 1.250), pages 22-23.

Victor: Bever, rile Zackenstil t Stnasboungrrpages 24-25.

Louis Grodecki, ItLe Style rrdu::r' de l-a Peintur€,snr verre en Fnancerr (lhe tthandrr style of glasspajrting in Fnance), pages 26-28.

Nigel Mo:r&an, ItEarly gnisai1le windows inEnglandrr, page 29.

Madeline H. Caviness. ttNew observations on theChannei School: A Freneh gtass-painter inCantenburyrrr pages 30-r3I.

Eva Frodf-Kraft. rrzum Werden den rrgotischenrr

Farbspnache in de:: GJ-asmalerei" (0n the changein colour-expression by nGothicrr glass-painte::s), pages 32-34.

Bnuno MilhJ-ethalen, rtKennen wi:: die Gxenzen undt,Iogfichkeiten fur d.ie Erha]-tung mittel-a]-ter-l"icher Gtasmalerei?tr (Do we know the l-imitsand possibilities for the preservation ofnredievaL painted glass?), pages 37-+6.

1e

generalitieszur restaunierung desrnarienfensters ausi st.patroki in soestausscrnschutzverglasungrecent r rorkdiscussion sectionabstracts

345€i

iuI. Per€z v Jorba and R. Collongues, rrRecherches

r€centes sun Ie processus d.e cor"rosion desvitrauxtr, page 47.

Jean-Mar:ie Bettenboul"g, rrles pnobl€rps de laconsenvation des vitr"aux de Ia cathddraJ-e deBoungesrr, page 48.

Ui-f-Dietnich Korg, rrzur Restaunienung de::Chorfensten der Stiftskirche zu Buekenrr (Onthe r€storation of the Choir window of theconvent church at BUcken)r page 49.

@!g lilg, rrPnobJ-ems with the EIy Glassrr,page 50.

Gottfreid Fr€nzeJ-, rrBenicht tlbe:: die Er"stelLutlgeines GJ-asmal-errei-schadensatlas fur dieBundesr€publ-ik Deutschlandrr (Repont on thepreparation of an atlas of darnage to stainedglass fo:: the Federal Republic of Germany),page 51.

Ernst Bachen, ttZu aktuellen Fragen der"Kons e nvi e:run g rni tte l-alte rl-i che r GIas ge mtsIde rr

(tirefy questions concerning the conservationof nedievaf stained glass), pages 52-53.

The Minutes of the CVMA Meeting ar€ r€portedon pages 55-58, and the CloEing Session is onpages 59-60. The booklet aLso incl-udes narnesand addnesses of the deJ-egates to theColloquium, and of the National- Conrnittees.

These a-bstracts have not been incl-uded inSection 6 of this News l€tter because they areavail-abfe in this bookl-et which is obtainable,f::ee-of-charge, from Arbeitstel-J-e CorpusVitreanum Medii Aevi Deutschl-and, Urbilstrasse84r. D-7000 STUTTGART 1.

)."2 THE THIRD GERMAN CORPUS VOLUME

The eno of the yean wiJ.l see the publie-ation of the third German Corpus Vol-ume (VolII, 1, Die rdttelalterfichen Glasmal-ereien inBaden und del Pfa.lz ohne Freiburg i. 8r"., byRudiger Becksmann). The publishem are theDeutscher Verlag fur Kunstwissenschaft, Berlin,and the volume wil.l- consist of 460 pages (308of text), including 171 figures and 40 ill-us-tnations in the text as wel-l- as 500 monochnomeplates and l-4 in col-oun. The published priceis expected to be considerabl-e and hence theedito:: and the publisher: have agneed to offer"

the .rolumes, on a per€onll- basis onl_y, toMembers of the Conpr:s at an advantageous pre-publication price. the figune has not yet beenfixed but r€set:vations for" the Volume may besent imnEdiatel-y to the Anbeitstel-le inStuttgar:t (at the address given at the end ofSection I.1).

f.3 IIEETING OF THE PROJEKTGRUPPE GIAS IN BONN0N ]3th MARCH 1"978

l-.3.1- New Chainman - Dr: J.C. Eennazzini

During the neet.i.ng P::ofesso:: Dr: Hor6tSchol-ze nesigned frcrn the position of l_eader"of the Projektgr"uppe and the members manimouslyel-ected Dr Jean-Claude Ferrazzini (from theIhstitut fur Denkrnal-pflage of the E.T.H.,ZUnich) to take his plaee. The next meetingis likely to take pJ-ace at the end of Februar.yor. the beginning of Manch, 1979 and we caasend our" good wishes to Dr Ferrazzini for. ahappy term of office and the onganisation ofnany suecessful meetings. Any suggestionsfor topics to be discussed at futune meetingsshoul-d be sent to Dr" Ferr.azzini at The Institut,cH-8092, ZtiRrCH.

-I.3.2 PaDer"s read at the nreeting

The following papers wer€ r€ad at thefi€eting; copies were neceived too ].ate forabst:racting in this Number of the Newsletterbut abstracts wil-l- be given in Nt No.28.

C. Se1lqeq 4141B. Camagg, ttUntemuchr:ngen vonffirt) mit der" ui-vrs-NlR-Spektroscopie r:nd den Elektronenspin-r€sonanz (ESR)" (The use of UV-VIS-NIR-Spectroscopy and el-ectron spin resonance fonstudying l-7th-centurl/ forest-type glasses).

G. .Naue:: grd E. Krrv, ttZu:t numenischenKfas sifikation rUmische:r Glaser aufgrund ihre:rElenentgehal-ter' (A numerical system for cJ.assi-fying Roman glasses on the basis of their3chemical composition).

J.C. Fer"nazzini, rrvonschJ.ag zul: theoretischenEnrnituung den Zusammensetzung der GL8ser vonJohannes Kunckel- ( 1630-l-703)" (Suggestion for,the theoretical i.nvestigation of the compo-sitions of Johannes K1mckeJ.ts glasses (1630-1703)).

I"lartha SDitzer-Aronson, rrTitan a]s moglichenIndikaton ni tte falte nli cher ge nnlte:: GJ.aser rl

(Titanium as a possible indicaton of medievafstained glass).G. Schulze, I'Untersuchungen an Rubingfas ausRastattlt (Reseanches on r.uby glass furcm Rastatt).

H. Scholzer "Charaktenisienung rrkrankerrlGldsen" (The charactenisation of rrsiekrr

glasses ) .

1.4 INFORMATION REQUIRED ON CONSERVATION

PRACTICES

PROBLEMES DE LA CONSERVATION DES VITRAUXANCIENS : la r:echerche international.e

Consid6r:ant ltampleur des probl€nes posdspar,+e conservation des vit::aur anciens su:: leplan intemational, un t:appont gdn6raJ- sunces pr"obl€res gui regrouperait tous J.esr6sultats scientifiques et techniques nis enapplication actuelLetlent dans l-e monde seraitdrune aide pr€cieuse pour Les chercheuns etles techniciens de Ia consenvation.

Le L.R.M.H. se prlcpose de r"daLiser cerapport avec fa panticipation de nembres duConitd Technique et celle de tous les chencheurstravaill-ant sur cette question.

Les thBmes proposds figur€nt dans l"esch6ma ci-dessous.

Nous vous se::ions reconnaissants de bienvoulour. nous adresser vos comrentaires et untexte rddig6 sun fes sujets qorr€spondant ivos exp6riences pnatiques.

Nous vous nener"ciens pan avanee del-tint6r:€t que vous voudrez bien apponten t lar€aJ-isation de ce rapport pnimondial.

l,es r€ponses sont 3 adresser l:Monsieur Jean-Manie BETTEMBOURGT Secn6taine duComitd Technique, L.R.M.H.r Cheteau de Champst77420 CHAMPS SUR MARNE.

RESTAURATION ET CONSERVATION DES VITMIIXANCIENS (schdma pr:opos6) -

r/ NETTOYAGE DES VITRAUX ANCIENS

l-0- Altdration des venresI01. Composition des vernes

- LO2. For:nES dral-tdr"ation103. PollutionlOLl. Bibliognaphie

1l-- Nettoyage m6eaniquel-l-0. Fibne de ve:rne1.1-.1-. BnosseI12. Polissage1l-3. Abnasion114. Dangers ou avantages oe ces

Procdd6sJ-15. BibJ-iognaphie' dtudes r€alisdes.r.

I2- Nettoyage pan ultrasonsL20. Bains utilisds (eaur produits

chirniques )121. Dange::s ou avantages du pnoc6d6122. Bibliognaphie, €tudes r€alisdes...

1,3- Nettoyage chirnique130. EauJ.3J.. Produits chimiques (J.iste des

produits utiJ-isde)'I32. Dangers ou avantages des procddds133. Bibliographie, dtudes r€atis6es...

J,4- Autres r€thodes

?/ RESTAURATION D$S VERRES BRISES

20- Pl-ombs cle casse (tnaditionneLr J.arpde cuivrre... )

3/

21- Collage bond I bord (liste des coJ.l-esutil-isdes )

22- Co[age sur un verre blanc moderrre23- Collage bord t bord et doublage pan

rm verte blanc (nature du joint)24- Etudes r€alis6es, bibliognaphie...

PROIECTION DES VERRES

3O- Fil-rs de rdsine (nom des produitsutiLisds )

31- Doublage dtrm venre palr un verreblanc (nastics utiJ.isds poun Ies ce l-le nren t )

32- Doullage drun panneau pan un panneauen verre blanc

33- VerniEnes extdrieur€s34- Autres p:rocdd6s (filurs inonganiques...)35- Dangens et avantages des proe6dds

(condensation...)36- Etudes r€a1is6es, bibliographie...

I{ISE EN PIOI,IB

40- Natune et fonne des plombs utiLisds(dinrensions, etc...)

41- Composition des plombs42- Remplacenent des plornbs oniginaux43- l€thodes de dessertissage des plombs44- Techniques de remise en pl-onbs

MASTICAGE DES PANNEAI,X

50- Mastic tradi.tionnel (huile de J.in...)51- Mastic dlastorGne (nom des produits)52- Avantages ou inconvdnients des pnocdd6s

(vieilJ-issenrent, difficult6 dtemploi., . )53. Bibliognaphie, Studes r€alisdes.,.

POSE DES VITRAUX

60- Nature des fennures (barfottieres,vergettes. . . )

6J.- Mastics (norn des prrcduits utitisds)62- Avantages ou inconvdnients des procddds63- Bibliognaphie, 6tudes r€al"is6es...

RESTAURATION DE LA GRISAILLE

70- Al-tdnation de Ia gnisailJ.e71- Recuisson72- Refixage par. une r€sine (non des

produits utiLis6s)73- Restdur.ation de la gnisaille (repeint,

poudre de graphite... )74- Avantages ou inconvdnients des pnoc6dds75- Bibliographie, 6tudes r6alis6es...

1.5 PRELIMINARY NOTICE OF THE VIIIth CONGRESSOF THE ASSOCIATION INTERNATIONALE POUR

LIHISTOIRE DU VERRE

Ihis Congress wil-l- be beld in Englald inSeptenber 1979, and the pneliminary pnogriarmeenvisages wor,.king sessions as foJ.lowb!-

Roman gJ.ass, hednesday l9th Septernber J979Medieval, $rzantine and fsJ-amic gtrass, Tuesday

2Oth Septenben (rorning)

Renais,senc*e gJ-ass, Tuesd.ay 20th Sept. (afternoon)17th'to 18th centunies, Fniday 2J-s.L September

(rorning)Lgth to mid-l-gth eentu::ies, Satunday 22nd Sept.

(morning)Mid lgth to 20th centunies, Satur.day 22nd Sept.

( aftennocn )Scientific analysis and consenvation in

Liverpool on Monday 24th S3pt, (afternoon).

During the first week, when neetings willbe held in London, visits wiJ-l be paid io theB::itish Museum, the Museum of London, theAshmolean Museum (Oxfo::d), the Seience Museum,and the Victonia and Albent Museum.

The reetings in London wil-1 be foll-owedby a Post Congress Toun (Sunday 23r.d toTuesday 25th Septemben) to Dudl-ey (tbe newGl-ass Museum), St Hefens (the pilkington Gl-assMuseum) and Liverpool (ttre City Museum), andto Scotland.

1.6 NEW INSTRUCTIONS FOR AUTHORS

this News Letter" is the fir-st to bepublished by ICCROM and the EditorialComrdttee is gnateful to them for taking oventhis responsibility fron the Pninting unit ofthe Univer"sity of Yor."k. Gratitude is aLsoexpressed to the Univensity, and especiallyto the Department o.f Physics for havingpnoduced and published Nos. l-l- to 26 incl-u.sive.

In future it will be prrcduced by photo-r:eduction onto offset pninting plates usingthe original- tWescl.ipt. Autholrs nust there-fore be panticula::ty careful to foLlow theseinstl"uctions conpletely. the contributions(in English, Fnench o:: Gennan) should be typedin single spacing in nannow colulrn width onone side onLy on good quality paper, Themaximun width of the colunn rf typed matten is105mm [4 1/8 inches), but wide tab.les can beaccornnodated acnoss two coh.urrs, in which casethe maximum acceptabl-e width is 22O nn l8 1/2inches).

Typen::itens with srnaLl typefaces shouldnot be used because the l.eproduction pnocessinvolves a reduction in size of about 309op andver:y black ca:rbqn ribbon shoufd be used toprovide good contnast. Pages should benunbered ir !94 and the t5pesc::ipt shou.l-dnot be folded or cr€ased in any way.

The typescript shoul-d b.git ggEliSnase with a sumrnarv in Enefish of not more than20O words. Authons ane encounaged to provrdefiffi#i6; in French and Gerrnan also, but ifther€ is any difficulty in pneparing an Englishsunrnary, the Autho:: should contact D:: BnunoMtirl-ethalen ( Schueize ris ches Lan desrnuseumtPostfach 3263, CH-8031 ZURICH-23' Switzerland).Line drawings on photographs should be pastedin the text at the appnopriate p.Iaces and themaximum widths arE as befor€ (tts mm on 260 mrn).

Captions should be typed below each illustration.Pllase ::emember that articJ-es as received wiLlnot be retyped. Typescripts should be sent toDr Mir'h.l-ethater at the addr€ss given above.

+/

6/

7/

e ztt? restaur.ienung degrnarienfensters von 1r;4s'aus st. patnoki in soest

by qlf-Cbtrlch koFn

Enslish Summarv

rrRestoration of the tMarienfensterr (1549) in@'

In addition to the wel-l--known medievalwindows in St Patr.okl-i there is a less-known,but neverthel-ess important, Renaissancewindow. This window was a gift from the towncouncil and was made in l-549-52 by JohanGlasemecker of Frdndenberg/Ruhr. An inscriptiorrecords that the window was restored in l-876md missing parts wer€ r€placed. It repr€sents"The woman cl-othed with the sun" and two angels,holding a crown hoven over hen. The artistis not known and funther stylistic investi-gation is reguired.

In 1941- the central- panel of the windowwas severely damaged. A few fragments of theheads and robes were recover€d by Hans Wentzel"but have since been l-ost. The window is nowbeing restoned in Dr H. Oidtmannrs workshopat Linnich.

Restoration of the original- parts extendsfrrcm simple gJ-ueing of cracks to pl-ating andfixing of l-oose paintwork. Analdite is usedas the adhesive and for the intenlayen ofIimited ar:eas of plating, and the window wilLbe entirety re-leaded. Isother"mal glazingwill be insta.Ifed together with a UV-absorbenttransparent sheet.

The restoration is being carr"ied out inclose co-operation with the Landeskonservatorof Westfal-en Lippe, and the work is sponsoredby the Government of Nord:"hein-Westfalen.

(Summary prepared by Uff-Dietrich Kornand translated by Bntrro MUhLethalerJAdditional note by Roy Newtoir: in response tomy enquiry, Dn KORN informs me that the UV-

absorbent material is incorporated in tbeplastic interlayen cf the 6nn laminated safetygJ-ass, descnibed as'rKinonglas-Kristal-I rn-itU.V. -absorb€r", supplied by VereinigteGlaswenke, JUlicher Strasse 495r D-51O0 AACHEN.

The name suggests that a quinone-type U.V.absor.ben may be used.

'.Uber Rang r:nd Bedeutwrg der romanischenGl-asmalereien in den ehemaligen StiftskincheSt. Patr:okli in Soest ist mehr:fach geschriqbenworden. Nahezu rmbekannt ist indes ein weiteresbedeutendes Werk den Glasmal-erei, das derse.LbenKirche geho-rt: das Marienfenster von 1549.Daftb gibt es rnehr:ere Grunde:

l. Eine zusammenfassende Darstellung dennachmi tte lal-terlichen monumen talen GLas gemdldeDeutschlands ist bisher nicht geschriebenworden.2. Die mittel-al-ter.l-ichen GJ-asmal-ereien inSoest sind so umfangrreich r.rnd zum Teil sobedeutend, dass dies Renaissancefenster danebenvergleichsweise uninteressant errschien.3. Das Fenster ist seit 1941 nicht mehr: zusehen.

Auch vor l-94I werden nun wenige Besuchenvon St Patlokl-i das Marienfenster mit Bewusst-sein wahrgenonrnen haben. Es befand sich im

Obergaden des sUdlichen Querhauses, hoch Uben-eiiidiri ettar in den Ostwand.

Das Fenster ist eine Stiftr:ng der StadtSoest. Der Rat der Stadt schLoss im Jahre 15t+9

mit rrmester: Johan glasenecke::rr aus Fr6bdenbergan den Ruhr einen Vertrag Uber die Her8teLl-urgund Liefer.ung. 1552 war es fertig; MeisteriJohan Ryneken machte das Eisenwerk dazu. DerAnlass fttn die Fensterschenkr:ng in dieStiftskirche St Patrokl-i wa:: vielleicht dieBeschwerde des Laadesherrn, des Herzogs vonCleve, dass t'die Capellen und ander€ Gotts-hdusen, die glassfenster irn Mtlnster (= StPatrokli)r..repanint'r wer.den mussten. Mdgli-cherweise war die Fensterstiftung eine Gesteder Wiedergutmachung fur die Schdden, die inden Wirren der Reformationsjahre im katholischgebJ-iebenen Patrokl-istift entstanden war€n.

Das Fenster, das 1876 von Victor von derForst in Munster restaur"iert r.md zum Teilergenzt wurde, zeigt in fttnf Zeilen und dreiBahnen die Madonna -i.n der von Wolken unrgebenenStr.ahlenglorie. Ober ihr schweben zwei Engel;sie halten eirre sternenbesetzte Krone. DieFigurenkomposition wird an den Seiten eingefasstdurch schlanke Kandefaber€eul-en nit Masken,Blattkel-chen, geriefelten Sdul-en und Kngufen.Sie tragen zusamrrEn mit einer MittelseuLemehrfach vensehlungene volutenbttgen mitAkanthu,sl-aub, die wie Masswerk den Fenste*-scheitel fU.Llen. Sie stehen weiss und si].bergelb gegen tichtblauen Grund. Weiss u.rrd GeIbsind auch in den figUnl-ichen Teil-en dieilauptfarben, begleitet r:nd akzentuiert dunchRot \rnd Viol-ett an den Engelsfl-ttge.l-n, denSchdrpen der Engel rnd im Gewand der Maria.- Hart am unteren Rand steht in einer Kartuschedie Jahreszah.l- rrl-5r+9rr, dar{lber in einem:..edaitlon die Inschrift irRenovatum 1876r'.

Wir wissen zwar, dass Meister JohanGl-asenecken das Fenster gefentigt hat, niehtaber, wer den Entwunf fieferte. In den SoesterLokaltradition heft sich hartn8ckig der Nane'rAldegrever-Fensterrr. Es gibt dafur keinenBeleg, doch weist den Fornenschatz derOrnamentik enge Beziehrngen zu HeinriehAldegrevers graphischem Werk auf. Besondersauffal.lig ist die vierfache Wiederholung dendrei Oval-masken an den Kandelabersdul-en. Siesind auf den von Al-degr€ver. um 1525 gemaLtenFJ-Ugeln des Marienal-tars in der SoesterWiesenkirchre zu finden. Eine genauestiLknitische Untersuchurg des Fensters stehtnoch . aus .

Am l-3..lune l94l- durchschlug eine Bonrbedas Fenster. und zertrumnerte die Figuren dermittleren Bahn bis auf geringe Reste. EinigeKdpfe und Gewandteil-e sowie Stgcke den ertral-tenen Rahmung konnte Haos Wentzel bei derBergung den Soester Glasmal-ereien aufTrehtrFnlassen. Seither lagen die Fragmente in einenKiste. Manches Stuck ging in der Fol-gezeitverloren, auch die Kdpfe den Maria lnd desChristkinds sind seit vielen ,Jahren verschollen.

Im Zuge der Gesamtrestaurierr.mg vonSt Patrokl-i, die seit einigen Jahren im Gangeist, wir.d nun auch das Marienfensten wieden-hergestell-t. Obwohl durch den Bombenschadenvon 19+1 die wichtigen figunlichen Teileweitgehend zer.stdnt sind, ist eine Rekon-strul<tion doch nr6glich r:nd verhdl-tnismdssi geinfach: Es gibt eine recht gute Gesantauf-nahme aus der Zeit un 19OO und die Detaif-photos der verEchol-l-enen Kdpfe, ausserdern

SOEST. ST. PATtrclKLIrnaFisnfensten von 1549 2rJatand 1977

enthdlt das Tafe]wenk i'Vo::bildliche Glas-mal-ereien aus dem speten Mitte.la-Iter r.md denRenaissancezeitrr (Berlin l-91-I) die massstab.-gerechte und sehn zuverrlessige far."bigeWiedengabe eines aquare.J-fie:rten Kantons.Diese, 49 x 16 cm grosse Abbildung wundephotographisch auf das fonmat des Fenstersmit ca. 4r5O m Hdhe ver:grosselrt. DieseVergdsserung dient nun in den WerkstattDn.H.Oidtnnan in Linnich wiederum als Kantonf{lr die Rekonstr:uktion den ve::l-orenen Teife.

Die Restau:rien:ng den erhaltenen Partienumfasst die ganze Skafa der Mdglichkeiten vonder einfachen Kl-ebung gesprungener. Gl-dser biszun doppelseitigen trockenen Doublierung undzur Schwarz lotsichenung. UnzHhlige Sprungemilssen geschlossen, konplizier:tere BrtTchedurch Niete und Idtpunkte gesichent wenden.Fehlende Spl-itter werden dur.ch fanbl-ichpassende, sorgfeltig einges chliffene Gl-dse::ersetzt. Al-s Kl-eben wird Analdit benutzt,sowohJ- zum Kleben von Sp::{lngen a.Is auch zu::

F___'-l zeratiiFt€ teit€

FiI,i-Tl verschollene teile

partiel-Len Schwarzlotsichenung. An wenigenStel-len mrlssen zentrummerte Gl-esen mit Ana.l-ditr.Uckseitig doubi-iert wel"den. Die Malerei istgltleklicherweise nur" in geningern Masseabgenieben oder angewittert. Stdrende Spnurg-bleie werden entfernt; das gesante, sehrbrilchige B.l-einetz wird erneuert. Die Fel-de:re!:hal-ten einen stabilen Rahrnen aus l,lessing-U-Profi]en und wer:den mit einem Abstand von etwa5 cn vor3 einer isothermischen Schutzverglasungaus Ver:brnd-Sichenheits glas nit UV-S cbutzfolierpntiert. AIle Massnahmen werden im einzebenin der Werkstatt rnit dern Landeskonservatorvon l{estfafen -Lippe besprochen und a.bges timnt.

Es ist sehn enfreulich, dass du::ch denEinsatz den Pnopsteigemeinde von St.Patrakfiund durch die grosszugige finalzielle Hilfedes Landes Nor"dnhei-n-Westfal-en eines d6rwenigen bedeutenden Zeugnisse der Glasnalereider Renaissance in Westfalen du.nch dieRestaurierung und die Rekonstruktion wieder-gewonnen wenden kann.

s bussenschutzverglasung3.T KLIMA]ECHNISCHE VERSUCHL

English Summa4r

this nepont describes a laborator:y-basedexpenimental study of two types of external-pnotective glazing, one where internal venti-lation was used, and the other with extema-Lventilation. Two c-l-imatic chambers were usedand the window-assembly was pfaced betweenthem. The tempetratures and t:e.l-ative humiditiesin the charnbers were adjusted tc reproduce thealpine weather conditions, and the intenna]-eonditions, both actuaLly measul:ed at theconvent chunch of St Mar:ia Stnassengel, i.e.five temperatures fo:: the outside ain (-l_soc,L.59c, fOoC, 25oc and 35oC) and foun temper-atur€s fon the inside air (2o, loo, fso and20oC). the effectiveness of the extemal-gl-azing was assessed by the extent to which itprevented condensation from occuir^ing on themedieva-L stained gl-ass. It was concl-uded thatinterna] ventilation was betten than .externalventilation, at least under these Austr"ianalpine-climate conditions, because, on 13 testoccasions employing the most extreTne conditions(-l-soC outside and 2oC inside), cond.ensationoccunred 9 times when exterrral ventilation wasused but only twice when the eavity wasventil-ated to the inside of the ctrunch.

Sinn und Zweck von Aussenschutzvenglasrngenwunden in den l-etzten Jahnen ausfuhnlichdiskutiertl). Es besteht kein Zweifel, dassdiese Konservierungsmassnahne, die das mittel-aLtenl-iche Gl-asgernAlde se Lbst nicht unmittelbantangierat, sonder:n ihm sozusagen vcn seinenUrngebung hen Schutz gegen die Verwittenung undgegen die den Verfallspnozess fd:rderrrdenljmwel-teinfl-Usse gewahrt, dont, wo sie ohneSchwierigkeiten anwendbar ist, zu denpraktikabelsten Massnahrnen gehort, die derDenkmalpflege zu'r, Zeit zun Venfugr:ng steht.Unabhdngig von diesen grundsdtdlich positivenEinstel-lung und den bislang vorhardenen gutenErfahnungen mit Auesens chutzvenglasungen istdie Diskussion dont noch irnmer im Gang, wo esdanum geht, Detailpr:obleme zu l-dsen, von denendie Wi::ksamkeit dieser Konsenvienungsrnssnahmeabhdngt. Dazu gehouen vor al-l-em Fragen denKonstnuktion, d.h. die Diskussion einesbestimnten Systerns in de:: Anlage den Schutz-venglasung, das eine sinnvolle und ausreichendeBel-Uftung ganantiert, etc. Die Tatsache, dasszur: Beantwortung dieser Fnagen noch sehr wenigEnfahnungswente vonliegen, weiL eine system-atische, danauf abzielende Kontrol-l_e instal-L-ierter Aussenschutzverglasungen s chwelr mdglichist, muss ihne Diskussion weitenhin im Ganghalten. Von diesen Voraussetztrngen ausgehend,hat das Bundesdenkmalant im Fnflhjabr !977 beiden Bundesversuchs- urd Fonschungsanstalt inWien, Abteilung Ke.l-te- urd Klimatechnik, das

Das in Osterreich pnaktiziente System derAussenschutzvenglastrrg variiert das ii derSchwei.z und in Deutschland verhendetea In den

Versuchsp::ogramm rrKl-imate

trag gegeben, llber dessenFol-genden ku:pz benichtet werden sol_1

: b:rlpinalen Fenstenflaz wenden d.ie Tafeln derSchutzverglasr:ng eingebaut, die mi.utelalter'-l-ichen Scheiben etwa 8 - l-O cm zurUck insKi::cheninnene versetzt 3). Die offenen Fnagen,die sich dabei in den Praxis stelleD, geltenin ersten Linie der Klimatisierung der zurUck-versetzten mittel-altenti chen Scheiben I d.h.der BeLUftung des Zwischenraumes:

a) In welchem Ausmass ist eine BelUftung fUndie beabsichtigte SchutzfrErktion notwendig,d.h. re l-che k.l-imatischen Bedingungen s chliessenKondensatbiLdung, die es r:nbe{ingt zu verineidengilt, aus bzw. schn&rken diese ein.

b) WeLche konstnuktiven Voraussetzungengewdhnleisten diese Bedingungen; wie gross nussden Abstand den beiden Vengl_asungen voneinander:sein, reJ-che offar:ngen zuunte!'st ttrJd zuober€teiner Bahn, sowie eventuell auch an den Seitensind notwendig oden gttrstig, etc. 4).

Neben diesen Fragen war es auch das inl-etzter Zeit nehrmal-s zun Diskussion gestelJ-teSystern einer Aussenschutzvenglasr.rrg mit aussen-seitigen Pel-tftung bzw. Hinweise auf dessenVorzuge 51, die in dieses Versuchspnogrammmiteinbezogen wunden, um dunch einen Vergleich-stest Anha.l-tspunkte tlber die Hirksamkeit,d.h. Vor- und Nachteile beider Konstruktions-systerne zu bekommen.

Die Vensuchsanor&rung engab sich dunchdie l-okalen Gegebenheiten im Labon der Bundes-vensuchs- r:nd Fonschrurgsanstalt AreenaL inWien mit zwei unabhs:gig voneinander klinat-is ie r"baren KLimakammerrr und eine n venbindeodeogrossen TUrdffnung. Diese bot a.l_s ftFensterrizwischen den beiden Kamnern al_s rrlnnen-tndAussenraunrr die Mdglichkeit, die beidenenwdhn ten Kons truk tionssys teme nebeneinanderzu installieren:

Ygniante I (von innen belUftet) nach dem in0s te nre ich pr aktizie rten t(ons tr,uktionssys tem,

Valiante A (von aussen beliiftet) nach dem inYonk/Eagland ge testeten Model-f b/,

AIs nftte]aJ-terliche Verglasurg dienterrje zwei Uber€iilandergestel_J-te (aus nitteL-alte nl-i chen Scherben zus arunen gese tze ) S cheibenaus Mania am Gestade, das Ausrnass den simulier-ten Fenstenbahnen betrug zid<a 2r2O m x OrT5 m.Dass dieses weit unter" den u-bl-ichen Dimensionenzu::Uckblieb, schn&rkt die Ar:ssageknaft dergewonnen Wel:te naturgendss etwas ein, derengrundsdtzliehe cul-tigkeit wind davon a.be!nicht betroffen.

An klimatischen Bedingungen wunden demVensuchsprogramm das Innenkl-ima den Kirche vonMaria Strassengel (Tenpenatun- und Feuchtig-keitsmessungen 1974/75) und die allgemeinenk J-imatischen Ve rhdl-tnisse im AJ_penniurn nitihren rn6llichen Extr€mwerten zugrunile gel-egt.

Um bei Va:riante I zwei verschiedeneAbst€lnde zwischen gl-asgemelde und S chutzver,.gl-asuog zu testen (zi:rka IO cm und ca. 2 cm),wulde das auf 13 Tage verteilte Klimaprognarnrnz r^ra imal- durchgef ah::en.

6

@.,7)Das Interesse gaJ-t in enster Linie der:

Fnage, ob und wie oft es zu den f{l:r dieGlas gern€llde ge fdhnJ.i chen Kon den s atbi ldun gkonmt 8). Hier fief den Ver:gl-eichstestz,.rischen den Varianten I und A kl-ar zu Gunstender Aussenschutzverglasulg mit innenseitige::Belttftung aus, und zwar so eindeutig, dass mansagen kann, dass die von aussen belufteteVar,iante ftln die klimatischen Ver"haltnisse inunser€m Raum nicht geeignet ist. Wdhr:end beider Vaniante I fallweise Kondensatbildungauftnat (bei 2 von 13 Positionen), kam es beide:r Variante A sehr oft dazu (bei 9 vcn 13Positionen) 9). Inne::ha.l-b der beiden Vaniantender. Ve:rsuchsano::dnrmg mit innenseitiger"Bel-uftung (Abstand ca. fO crn und ca. 2 cm)enwies sich die mit grlssser€n Zwischenraum(10 cm) als die g&rstigere. Die Tatsache,dass Kondensat zwan rel-ativ selten (ur:d nu::dann, r€nn bei tiefen Aussentempenatur€n der3Taupunkt im Kincheninner€n, etwa durchAtmungsfeuchte, nasse Kleiden, etc., krgftigangehoben wind), aben doch auch bei den am

besten abschneidenden Va::iante auftritt undnicht nu:r bei kl-imatisch extrenen Bedingungen( - 15 12 / 2, 3 G:rad Aus sen -,/Innentempenaturen ),sondern auch bei Venhdl-trissen, wie sie etwain der. Uber.gangszeit im Fnflhjahr und Herbstmdglich sind (0r5/9,1 Gnad Aussen-,/Innen*tempenatu:r), ist ein wichtigen Hinweis, dasseine Aussenschutzvergl-asung (Va::iante I) wohlweitgehend jene Fr:nktion erf0J.lt, die rnan vonihn erwantet, dass sie die Gefahr einerS chwi tzwasserbildwrg aber nicht gnr.m ds €tz1i ehausschaLtet. Bei -I5r2/213 o Aussen- bzw.Innentenpelatgr darf den Taupr:nkt im Kirchen-innenen - Or8o, das entspricirt einer r€J"ativenFeuchte von 80% (bei einem Scheibenabstand voni.0 cm) bzw. einem Taupunkt vcri - 3r9o,entspnechend einen nelativen Feuchte vcn 63%(bei einem Scheibenabstand von 2 cm) nicht0bersteigen. Bei. 0r5/9r1o Aussen- bzw.Innentemper:atun liegen die entsprechendenGrenzwer:te bei einem Taupwkt voll 6150,entspr€chend 84? rei.ative:: Feuchte (10 cmScheibenabstand) bzw. bei einem Taupunkt von6120 , entspr€chend 82% r€Lativen Feuchte(Scheibenabstand 2 cn).

Man wird diese Erkenntnisse irn Gesant-konzept krlhftigen Res taunie:rurgen berucksictr-tigen, d.h. alle ancieren Konser,vienungsmassnahmendanauf abstinrnen nUssen.

Inter€ssant ist die FeststelLung, dassdie Sb:dmrmgsgeschwindigkeiten zwischen denbeiden Verglasungen bei den Klinazust&]den,bei denen Kondensationsgefahn besteht, so hochsind, dass zwischen den Scheiben anndherndgJ-eiehe absolute Feuchte ist wie in derumgebenden Luft l-ur. In diesem Zusamnenhangenwies sich auch, dass die schmal-e Oftrnung anden seitlichen Scheibenr&rdern zwischen denGlasgemelden und dem Steingewehde bzw. denFensterpfosten keinen nachweisbaren Einf Lussauf die Versuchsergebnisse hatte, d.h., dassman auf die seitliche L0ftung (oden dieAbdichtung) verzichten rrr-rd d-ie stdr€ndenLichtschlitze soweit es geht schliessen kann.

Zusanrnenfassend kann n€m sagen, dass die[Klimatechnischen Versuche im Zusamrenhangmit dem Schutz nitteJ-alterlicher Glasfenster

dllrach' KIis sen s ch utz ve rg Las rn gen I der ie gbestAtigt haben, der in den Praxis bishenbeschnitten wu::de ff). A1s gnwrdsatzLichents chei denden Gesi chtspunkt im Zus ammenhan gmit diesen Konsenvientrngsmassnahrne ist wohldie Tatsache zu wenten, dass wrsene Gl-asgenAJ.de,die in den .Iahnhr:ndenten seit ih:rer" Fe::tigrngim Ablauf der. klirnatischen 'Jahreszyklen immenwie de n Kondenswasserbi ldr.rrg aus ges e tz t r^rar€n,an der Aussenseite dulchwegs sterker versrittertsind a].s an den Innenseite. Das heisst nichtsanderes, als dass zu den SchHden. di.e Schwitz-wasser" und Kondensfeuchtigleit sowie dieBel-astung des Glases in seiner Funktion aLsK1i mas cheidewaad an::i chten, zus dtz Ii- ch nochsehr" wesentlich andere Faktoren fUn denZe r"s tdr:ungs pl.ozes s ve lran tl,ort J-i ch s ein mtts sen,die offensichtlich von aussen auf das GJ-aseinwirken. Wenri win die Scheiben hinten eineSchutzvergl-asung ins Kircheninnene zuruck-ver:setzen, bieten wir ihnen dahe:: nicht nqrbessere klimatische Bedingungen, sondern einengnundsatzlich gthstigeren leb6nsraurn, von demwir: er"warten k6nnen, dass e!: den Ve::fallsprozess,wenn schon nicht zu stoppen, so doch wesentl_ichzu verzdgern verrnag.

Es wird dessenungeachtet notwendig sein,It'agen und Pr.obleme, die sich bei derpnak tischen Anwendurg diesen Konsenvie nun gs-massnahme engeben, weiter,"hin zu diskutieren,urn aus den Erfahm:ngen fUn die Zukunft zulerrren.

E. Bacher

I) AIle bibliognaphischen Hinweise flben diesahJ-neichen Diskussionsbeitnege zum ThemaAussenschutzvergl-asung finden sidr beiR.c. Neh'ton; Bibliog::aphy in British AcadernyOccasional- Papers I, Iondon (l-974); Biblio-graphy of Studies on the Deterionation andConservation of Stained Gl-ass, Art and.Anchaeologr technical abstracts, IIC, VoJ".LO,Nr.2, 1973, 5.139; sowie unter den StichwortenAussenschutzvez.glasrng und IsothennaleVer.gl-asrmg im Index zu den News Lettens I - 15(News. Letter ]5,/.1975, S.28 ff .) bzw. J.6 - 25(News Letter 25/L977, S.24 ff.).

Eirie Studie zum lttema Aussenschutzver-glasung hat auch Dr.. Gottfried Fr€nzel-,Institut fur Gl-asgemeldeforschr:ng undRestaunienng, NUrrlberg, angektlndigt.

2) Die Versuche wurden vom leiter denAbteilung Kdlte und KJ.imatectrnik den Bundes-vensuchs- rurd Fonschrngsanstalt, Herrn Dip1.Ing. G . Schue cke r, pnoj ektiert un d dur"chgefuhnt,dem das Institut ftln sein Interesse an denSache zu grossem Dank verpflichtet ist. Ders

abs ch liessende Beri cht Ube n rrKl-imate chnis cheVersuche in Zusanrnenhang mit dem Schutz nittel-al-tenlicher Gl-asfenster durch Aussens chutzver'-glasr:ngenn vbm 28.6.1977 (Zahl +O+576-440/383),den die Bundesversuchswrd Fonschungsanstaltvorlegte, ist die Grundlage ftln das vorliegendeRe sume.

3) Siehe E. Bachen, Aussenschutzverglasung,

in : Osterr.Zei ts chr. f .Kunst und Denkmalpf Ie ge,1973, XXVrr, S.66 ff., Abb.73,74.

4) Da das bis dato in dstenreich angewdndteKonstruktionssystem die Mdglichkeit bietet,di.e Abstdnde in einem gewissen Rahmen zuvariieren, l-assen sich auch bereits bestehendeAussenschutzvenglas lm gen neue ren Erkenn tnisseniibe:: das Ausrnass der notwendigen BeJ-UftunganPassen.

5) Siehe dazu die in Anm. J- zitiertenbibliog::aphischen Hinweise i"n den News Letters(insbesonde::s Nr.J-6l1975, S.5 ff. :urtd 22/I976,S.5 ff.) sowie R.G. Newton, Expenimental Studiesof the Pnotection of Mediaeval Windows UsingExternal- Glazing, Actes du IXe CoLloque Inter-national- du Corpus Vitr€at"urn Medii Aevi, paris8 - i2 Septembrc L975, in: Verr.es et r€fractaires,30/1, Panis l-976, S.80 - 86.

6) Al-s VorbiJ-d diente das in News Letter.I6/L975, Fig.4 bzw. 22/I97L, Abb. f, 2 skizzierteMode11.

7) Auf die genaue Versuchsanordnmg undDur"ch filhnng k ann hier ebens oweni g ein ge gan genwenden, wie auf die gemessenen G::dssen (8 Luft-,l-6 Oberfl-dchen- rlrld 2 Taupr.rnkttemperaturen,sowie 2 mittlere Luftgeschwindigkeiten) r:ndder€n Messger"gte. Diese sind in dem in Anm.2zitierten Bericht des Bundesver"suchs-undFonschungsanstal-t Arsenal- enthaJ-ten, der imBundesdenkmalamt auf.Iiegt. Dasse.Ibe gift f0rdie die Messwerte venanschaulichenden DiagrammeJnd TabelJ-en.

8) Kondensat tritt dann am Glasgemdlde auf,wenn die Obe::fl-dchentemper.atur den Taupr:nktder ungebenden Luft unterschreitet. Diesermascgebende Taupunkt ist bei det Variante I injedem Fall der Taupunkt der: Luft im Ki::chen-inneren. Bei der. Var"iante A jedoch den hdhereden beiden Taupunkte (Innenzustand, Aussen-zustand), G. Schuecker", Be:richt zit.Anm.2,S.6.- Die Strbnungsrichtu! der BeJ-iiftr:ng desZwischenr"ames erfolgt rein statisch du:rch dieDichteunter"schiede zwischen de:: Luft imKir.cheninneren und der Luft zwischen denScheiben. Wenn die Aussentemperatur. uber derTemperatur im Kircheninneren liegt, erfolgtdie Dur.chstr:dmung des Zwi-schenraurnes von untennach oben, im anderen Fal-1 von oben nach unten.(Gift fun die Varialte I, bei den Vaniante Aist es umgekeh::t.)

9) De:: Hinweis von Pnof.Newton, dass ge:ringeneAbstAnde bzw. kl-einere LuftungsschJ_itze beiden Vaniante A die Hdufigkeit der Kondensat-bildung etwas eingeschr€inkt hdtten, t::ifftsiche:: zu. (Dazu ist aben anzumerken, dassden Diffusionswiders tand eines mitte J_aJ_ter,-li chen GIas gems}des ge gen Fe uchti gkei ts durch -tritt unsicher ist, d.h., dass immen damitger€chnet werden muss, dass aus dem Kir"chen-inneren Feuchtigkeit in den von aussen beluftetenZwischen:raum durchtr.itt und dort die Kondens-ationsgefahn e::hbht.) Dessenurgeachtet bestehtnach den enzielten Daten dieses versuches keinZweifei, dass die ins Kircheninnere zur0ckver.-setzten Glasgemalde klimatisch gl!:stigeren

bedingr:ngen ausgesetzt sind a-l-s jere mit einervon aussen vorgesetzten SchutzvergJ-asurg..

10) G.Schuecker, Bericht zit.Anm.2, S.6.

I1) Ein tshnl-iches Ergebnis brachten dje f974/75 durchgerUhnten lhtersuchungen im Freibur.genMllnster:, siehe K.Geis, Raurrkl-ima und Schwitz-wasser.bildr:ng im Fr.eibunge:: Mtlnster, Oktobe::-L976 (gednucktes FaLtb.l-att) sowie G.Rdnicl<eund R.RO'nicke, Das Raumklima des FneibungezrPiilnstels und die Mogl-ichkeit der Schwitz-wasselbilci.wrg an den Buntgfasfenstern, Schal-l--stadt, 28 . 0k tobe r l-97 6 ( :las chins chr.if tli cheVer:vie lfdltigung ) .

3,2 COIIMENTS BY ROY NEWTON

ltle extr€mel-y intenesting repor'.L given inSection 3.f was received just as this NewsLetter was going to press and hence it has not.oeen possible in the tirne avaiiabl-e to preparee propen discussion of this valuable cont::i-bution to the prob-lems of how best to Ltseexter:na.l- protective glazing. Hor.rever, ther€are two aspects of this experiment which areWlrea.listic, and their. implications wil-l- haveto br: discussed before the conc.Iusi6ns can beaccepted, even for these extreme Austrianal-pine conditions.

The first comment is that no account hasbeen taken of tbe r:adiation fr.om sr.nlight, o::even fr"oni daylight. For. example, the experi-ments at present being camied out atCanterbury and at l'ork have both showo thatwinten sunshine will- produce a temperature of4OoC in the caiity (a temper:ature nise of atleast 35 degC) and this wifl modify theconcfusions to an extent r-hich is as yetunknowr.

The second comment is that surp::isinglyl-arge venti.Iation openings were used fonintroducing external air into the cavity. ltreseopenings were 5 nm wide and in eonsequence theair. velocity up the cavity was about 0.25 m/s,with the result that the stained glass was madeveny cold and condensation occur::ed. By com-par"i5o51, the experiments ca::::ied out in YorkMinster: in 1975 showed that the ventilationopenings fon outside ain shoufd be made assmal-l- as possible (in conlrast to inten-ral-ventilation, where they should be made as wideas possible). In fact the externaL ventil-ationsl-ots should prefer"a-bly be rrfully cJ.osedribeeause, in the practical- situation of a tangewindow, even rrcl-osedrr sl-ots al-lowed someleakage of air at about 0.02 m/s (20 nrnls) -see Tab-Le II on p.8 of NL No.l6, and theaccompanying discussion.

lhe undesir"abfe effect of these high ainvelocities in the Austrian expeniment can beseen fr.om the fact that the bottom of thestained glass was 4.7 degC colde:: than the top,and it will be inte:esting to see what happenswhen the slots are reduced so that the ai:: f]owis only 20 mm/s on even 2 mm/s.

zr recient r tctr.k

4.]. FURTHER TTSTS ON VIACRYL RESIN COATINGSEXPOSED TO WET SAWDUST

Readere of NL No.24 (fB Feb 1977) willknow of the test of Viacnyl resin descr:ibed inSection 3 (pages 6 - 8) in which a piece ofpoorly-durabl-e glass (Bnitish simulated glassNo.2) had been given one coat of Viacryl nesinand then exposed for l-0 months to wet sawdustin a darnp chamber in the medieval wal-ls ofYor:k City, where the average temperatune wasabout 7oC. It was concl-uded that the waterf::orn the sawdust, which contained organicacids and had a pH value of about 6, hadpenetuated the viacryl and attacked the gJ.assurrderrreath.

Ther€ wer€ two criticisils of this test.(a) Only a single l-ayer of Viacr:yt had beenapplied and hence it was possible that ther€had been a rrpinholerr in the resin through whichthe sawdust-water,rnight have penetrated andspnead under the ViacryJ. (l) Wet sawdustrnight be too aggressive an agent for the testto be a satisfactol.y one. The answe:: to (a)lies in the new exper:irnent, descnibed below,rnd the arswer to (b) is that thel"e was nosign of damage of the Viacryl by the sawdust-water and hence the liquid penetnated it bydiffusion. Centainly, the sawdust-waten isn'cre acid than ondinany rain and it isaggressive towands the glass but if the Viacr.ylfaiLs to exclude sawdust-water, then it wil-Lalso fail to excl-ude rain waten.

ltre new expenirnent, planned to takeaccount of criti-cism (a) was ther€fore car:riedout by Mr Co.l-e of the Cante:rbuny Stained GlassStudio. He first deepened the foun r€fer€ncemanks (A-D, shown in Figs I and 3, on page 7

of NL No.24) using a wr:iting diaupnd so thatthey wer€ again easily visibl-e. The sarnplewas then fnamed in lead and cemented asdescnibed on p.8 of NL No.24. Then he appliedtwo coats of Viacryl r€sin, the second oneiften an intenval of .24 hours at 2IoC so thatthe first coat coul-4 dry pnope:r'ly; thesecond coat was diluted, again as describedin NL No.24.

The doubLe-coated sampLe was again placedin the r,et sawdust fon f2 months and r:emovedon 2Lst Febmar:y 1978. The Viac::yl coatingagain had white bl-iste::s on it, rather J.ikethose in Fig.2 of NL No.24, although none wereas .lalrge as those ahown at (1) and (2) inthat photogr"aph.

The sma11 idtur€ of the blistem, com-pared with those found in January J.977, suggeststhat there had been less attack on the gJ-ass.When the leads were cut away, howeven, it wasfound that afl adhesion had been .lost betweenthe gl-ass and the resin because the resincoating came off at once and the glass wasfound to be wet and slippery. The index marksnwhich had been renewed by Mr Cole, had againneanly disappeard. Mn Cole agrees that theyar€ now near:Iy invisible, and thei:: appeare.nceunder the micnoscope is quite ror:nded. Hehas made some fresh manks neanby, usingvanious diamonds, and a1l- of these appeal:

rlarrow-end sharp-edged under the nicroscope,compared with the lounded and shalJ.ow appear-ance of the yea!-ol-d marks. this confinmsthat tbe sawdust-r.Eter can penetrate the doubJ.e-coating of Viacryl and attack the gJ.ass.

Ihe thr€e lines (1, 2 and 3 in Fig.l ofNL No.24) were again neasured with the Talysunfat Sheffieldr but ttle r€sul-ts al:e ambiguous.The rrcentre line avenagerr figures were1, 2.5 pn; 2, 2.2 pm; 3, 2.8 un; thus,compar€d with the figunes on p.8 of NL No.24,lines J- a,nd 2 are now fess rough but Line No.3is roughen. the changes in noughness anelarge enough to indicate that something hadhappened to the gl-ass under the resin, and acl-oser study was therefone made of the 12individual- Talysunf tnaces (i.e. one eactr fo:rIines 1, 2 and 3, made on the foJ.lowing dates:2 SepteTrber 1975i i.O Februar5t L976; 12 ,JanuaryL977 and l- March l-978) but no consistency inthe patterns (hi}ls and vall"eys) couLd befourd. It has ther€fone been concluded thatthe sawdust-water hasbeen attacking the gfassin such a manner that it sinulates the rough-ness of the original- airbresive tr€atment,using No.3 gr:it. In other words, the con-cJ-usion is NOT that the new attack has followedthe oniginaFeontouna of the glass, but newcontours have been pnoduced by attack underthe Viacryl which are rather like the air-brasive roughness but are sometimes rougherand soretimes smoothen. If this ccncfusionis cor.r:ect, the sawdust-water must be removingmuch mor.e than I0 pm of glass in a year, andthis explains why the dianrond marks have beenmade so much smoother.

With rririndsightrt the exper.inent couLalhave been improved by sputter:ing a patdr of anobl-e metal, such as go1d, on the sunface ofthe gLass at the beginning of the experimentto act as a refenence point (a t'bench markf)f::om which the J-oss of su::face of the g,l"asscould have been measured.. It had been bopedthat the l-ead firame would have helped to giveinforcnation on this point; the edge doesappear: to be sornewhat smoother, and naiseiirelative to the r€st of the glass butrinfortunately the edges of the glass ar€lrounded and no neJ.iabLe measur€ments can bemade. (.See also the discussion at tbe end ofSection 5.)

ltre experiment has now stopped becauseit is concfuded that the Viacryl does notprotect ancient (poorly du::abJ.e) glass againstweathering and it is even thought J.ikely thatthe alkaLine products which accuunrJ.ate underthe ViacryJ- may eventual"J.y do mor€ halln to theglass than leaving it unprotected.

4.2 USE 0F THE AIRBMSIVE I'llTH GLASS BEADSOF .DIFFERENT SIZES

Pnevious wo:rk in B:ritain, using the air-br"asive to r€move heavy crusts from rredievaLgJ.ass, suggested that the risk of damage tothe gLass fnorn abnasive particJ.es might beneduced by replaeing the abr"asive by minutegLass beads (ball-otini). This betief wasbased on (i) tfre extr€me difficulty in pnoduc-ing damage on the sunfaces of modenn mienoscapeslides wlren baJ-lotini were used, compared withthe ease with which damage occu:rned whenabnasives wer\e empJ.oyed, and (ii) the effective

I

t€hoval of the crustr and appar€nt lack ofdarnage caused to uedievaJ. gJass when baLlotiniwere used at the Canterbury Stained GlassStudio.

l{hen tests were carrried out at the YorkGJ.aziens Trust it was found that the baJ.lotinisupplied by G.E.C. Mechanicaf HandJ-ing Ltd.would damage the surface of medieval glassafter the crust had been removed. A r€-testof these baU.otini on.rnodern microscoPe sLidesstiil failed to pnoduce significant danrage, andit vras ther€fore agreed to test sone of thettCanterbunyrr ba]lotini and the resuLts showedthat it r,es conspicuously less danaging whenused on the sarle pieces of nedieval glass atYouk, than the rrYonktt baJ.Lotini.

A microscopic study of the tr.to delive:niesof baLJ.otini sliowed that the material fnornc.E.C. uedlanical Handling Ltd. had an averageparticLe size of 60 pn, whereas that used atCanterbury and obtained from Bassett Smith &

Co., london 8.I., was only about 20 un indianeter. Xhe kinetic enerry of ttre largerparticles was about 27 tines gr€aten than theener:gy of those used at CanterburS/. Thus itis not sunpnising tbat the rrEteriaJ. used. atYonk causes nlcre damage.

A sample of ballotini is now beingobtained fir,om the Ballotini MarufactuningCo4lany, of Barnsley, Yonkshirre, which is inthe palticJ.e range O-lO Um and it is hopedthat even betten r€suf,ts can be obtained withit. It is not known why it is easier todanage nredieval gJ.ass thair modenn microscopesLides but there are sevenal. possibilities;fo:r example, the surface of the micnoscopeslides is both polished and fire-finished;the rpdern gJ.ass rBy be handen; the weathered

s diecuagion sectionIhis is a comnent by Roy Ndwton on the

Report by Dti E. Bactrelr on tbe Test of V.iaaq/]at St Mg.ria am Gestade.

I have nead r.rith gneat interest andattention the repox't by Dr., Baehe:n on pages 5

and 6 of NL No.26 because it is most impoartantto estabJ.ish without any doubt whether a

.

Viacryl coating gives some protection to rnedievaLglass against atmospheric attack or whether, asis suggested by Section t+.1 of the plesent NL,the Viacryl IlEy eventually cause morre harm tothe glass than Leaving it unprotected.

D:r Bacher concludes that the Viacr.yl hasper:fonmed the tasks required of itr'but therreare tul] points in his account which I do notfully understand and which shoul-d be consideredfurther.

My first conrnent is that, in Sectiorr 4 oihis repont (i.e. p.5, co1.2 of NL No.26, tines4-1 ft'otn the botLorn), he states tlrat a compari-son of panels 4 and 5 with panel- 2 il-lustratesthe attack on unprotected glass du:ring thel-ast 5 years, and the extent of neathening ofthe protected and unppotected glass. Thissuggested to me that Dr,Bacher implied thatpanel 2 had bv 1976 .be*ejn cor.qgded FgFe tban it

'rnedi.eval" glass nay have a fissu:red surface.

4.3 MORE DUMBLE BLIJE f2th-CENTURY GLASS

PART 5

Some mone soda-rich bLue l2th-centur5rglass has been for..rnd by Miss Fi.ona GaLe in amid- J-3th-centurlr earthwork sun:rormding theLJ-th-centuy ehu:rcb of St. l"lary-in-Castro atDover:. The sample has the uomposition:SiO2, 69.7%; Na2O, ]6.59i K2Or J".4%; MgOto.7%t CaO, 7.0%; MnO, 0.5%; CuO, 0.4?;ZnO, 0.03%; PbO, 0.8%; AJ.2O3r 1.1%; Fe2O3,0.96%; P205, 0.9% and it is thus sirnilar tothe durab.l"e blue glass found at l{inchesten andquoted in Par:t 4 of this investigation(Section .I.9 of NL No.24, tabulated on P.4).A search for: glass like this stiJ"J. continuesat CantenburS/ Catbednal, but none has beenfor.nd.

These glasses irave also been analysed byNeutrDn Activation Anal-ysis at the univers'ityof Br"adfo::d. witb the following nesuJ-ts:-

Soda Antinony Inon Cobalt Tho:nium%%?ppmPPm

Winchester 514 i-3.5 1.4 I.2 530 6.4" 515 L7.2 0.9 r.l 470 < 2,7

OJ.d Sa:rum 516 J.4.9 I.5 f,7 6J.0 5.0. r ,' 517 ]3.O A.7 r.0 400 4.LDoven 531 16.8 0.9 0.8 330 3'2York (nreantl) 16.6 0.88 1.6 555 ?

,'. This is the [pan of the foun samples fronYork, quoted on page 7 of NL No.22.

Based on these N.A.A. r€sultsr there is nosignificant difference betileen any of these bJ"ue

l-2th-centut:y gl-asses.

was in J971; if so, it would be inportant forever5rone that this stroutd be demonstrated.

D:r Bache:r has kindly supplied two photo-gnaphs which are reproduced be1ow, and I am

now convinced that some of the pieees of glassare more conroded in 1976 ttr.an they were inl-971-. This applies panticularly to tbe upPerhalf cif the photognaphs and I am delighted thatDr. Bacher has pnovided these ilLustnations fonal-l to see. I must add that I do not know ofany instance in England where so much crustingwoul-d have occurced in only 5 years.

My second comment goncerns the changes insize of the tvto hoLes which had appeared in theViacr:y1 coating. In his Note No.6 (nea:r thetop of col.2 on p.6 of NL No.26) Dn Bachenstates that two sma].]. holes wene pnobablypr€sent in the lower palrt of panel No.3 when itwas fixed in the w.indow in 1971, and may havebeen caused by accidental dalnage; nor€ovelr nosubseguent enlangerent had been noted (rrEineVergr6sserwlg der Schadenstel-ten seither istnicht feststeU-banrr ).

This is not ny recol"lection of the situ-ation because I first knew about these twohofes when Mr Peter Gibson photograPhed tbe

1Cl

paneL in May 1973; his photograph showed onlyone hole pnesent. When I took my photognaphson l-3th May 197'+ there was stil1 only one holepresent but it had become l.arger. A photognaphkindly supplied to nre by Dr" Bacher in September1975 showed two hol-es in the film and the fipsthole had become }ar.ger stilL. Dr Bacher hasreplied that, in his belief, the holes hadnea1ly been there all the time but they couJ-dnot be seen because the Viacnyt filn wasbridging a gap between a piece of curled-up,partly-detached crust and the r€st of thecrust. Thus, eventually, the "bnidgesil ofr"esin could have been broken nrerely by windpressur€, or. other kinds of damage.

Thus, it seems that we have pnobablyLearnt as much as we can fi:om this interestingfirst experiment, but there is an ungent needfor a really critica.L experifnent to be ca::riedout to discover what happens to a perfectlyglg piece of medieval glass when coated with

Panel No.2 at St Maria-am-cestade, as photo-graphed in 197l- after cleaning with water.By countesy of Dr Bacber and the Bundesdenk-malamt, Neg. No.N61526.

6 abstFaetsThe pape::s read to the XIth Interriational

Congress on Glass, hel-d in Pnague in July 1977,have been published in 8 voJ_umes compnising3837 pages in all. the papers ar€ esseDtiatlytechnical in nature, but six of them are ofpotential- intenest to scientists concerDedwith the deter"ioration of g]ass.

268. HENCH, L.L. (1977) "PhysicalChemistry of Gl-aEs Sunfacesr', see p.IO of NtNo.25, the full paper" has now been publishedin Sunvey Paper.s Vo1.II, pp. 343-369.

3O2. AHMED.J.A., ASHOUR. c.M. andEL-SHAMY. T.M. 11977) rrEffect of reltingconditions or, the c::ystal-l-isation of cup:rousoxide and coppen in glassrr" Pnoceed.ingsVol II, pp. t77-L87.

-Glasses of conposition suiteble for the

V'iAcar'yliand exposed 1n an accelerated weatnen-ing test. The essential- experimentaL require-ments were pnecisely defined at the rneeting ofESF rrexpertsrr heLd in Munich on 25th Febnuaryl-976, but the proposal to do the work was notimplemented. However, it is hoped that suchan experiment will be carried out'at theUnivensity of Sheffield duning 1978. I hope,a.Lgo, that the new test progranrne. to becarried out at Vienna, can include a pieee ofmedieval glass having a pg+S-kggfllgggg$49, (such as one which has been gr"oundflat and polished to an rroptical" finish,say within one or two wavelengths) so that anychanges in the sur"face rmden the Viacnytcoating can be precisely defined. Another,aspect, which unfortunately was ignored inthe sawdust-experiment at York, described inSection 4.1, would be to test the pH value ofany wetness detected unde!.neath the Viac:ryl:fjt gan-!. Degre-g-g.$, instead of usingCital 12-12 as had been intended.

Panel No.2 at St Maria-am-Gestade, as photo-graphed in 1976, after exposur€ to theatmosphere for 5 years.in an unprotectedstate. By coul"tesy of Dr Bacher and theBundesdenkmalamt, Neg. No.N71167

pr.oduction of cuprous oxide aventurine glasswene pr"epaned under: differrent rnel-ting con-ditions, differ:ent mel-ting temperatur€s o!'times or under neducing conditions by theaddition of metal-l-ic inon powden. Ttre number,size and type of cr5/staLs pneeipitated inglass after heat-treatnent wer€ determinedfon each g1ass.

Ther€ was a qualitative agreenent betweenthe r€sults of the effects of telperatur€ andtiue of melting. Incrreasing either temperatur€and tir€ of nrelting increased the nunber ofcuprious oxide crystals while their sizedecreased. Itrese changes wer€ attributed tothe effect of incneasing tenperature on timeof melting on the interrnixing of the liquid-liquid phase sepal:ation which occurs above theliquidus temperatur"e.

11

The addition of metallic inon Led to theprecipitation of netallic eoppen crystals.ltre dimensions of these cnystals varied withthe subsequent heat-tlreatment. The effect ofinon on the reduction of cupnous ions and theeffect of heat-tr€atment on the size of thecrystals precipitated are discussed. (Author.s I

abstnact. )

303. EL-SHAMY. T.M. and AHMED. A.A.(1977) nConnosion of some common sil_icateglasses by aqueous solutionstr, P::oceedingsVoJ- III , pp . .181-19 5 .

A study has been made of the conrosion offive industrial- silicate glasses of comrnoncorsnercial application. the study involvedtreatment oi powdened gl-ass with watet:, O.ll'l

.HCt and 0.1-N NaOH fon a fixed time at fOOoC.The extent of co::nosion was assessed byanalysing the sol-ution fon the main corr:osionproducts at the end of each expe::iment.

The quantities of sil-j.ca extracted fromthe five glasses studied foll-owed tne ol:deracid < waten << alkali I itEtr glass wasexceptional in that the acid extracted moresilica than fiater. Calciurn and magnesiumextraction by the acid was noticeably greatenthan the extracti.on by wateri both oxideswere practical-ly not extracted oy the sodiumhydroxide solution.

Extr.acti.on of the nain glass-for:mingoxides in vanious aqueous solutions is dis-cussed in r€lation to the constitution of thehost gLass. Basic ru-Les are deduced whichwould enabl-e the prediction of the corrosionbehavioun of"a glass frorn its cornposition andthe conditions to which it will be subjeeted.(Authonsr abstnact.)

304. HUFF, N.T. (1977) rrThe developmentof gtass-p::openty corr\el-ation equations tt,Pnoceedings Vol III, pp. 397-406.

As large computeus have become easilyaccessibl-e by gLass technologists the deve.l_op-ment of empir.ieal and theoretical equationslelating glass composition to prope::ties hasbecone fainly commonplace. However, unlesscare is taken in developing the equations,use of these equations can lead ane to makeincorrect conclusiorrs negarding the variationof propenties with composition. This papenfinst Looks at tbe theor€tical and ernpi::icalbases one can use to devetop property-compos-ition conrelation equations. Some of thesubtl-e but important problems which rnay anisein the calculation of the equations are thendiscussed. These pnoblems may anise fr.omusing readily avail-abl-e but infenior. mathemat-ical algorithms, fnom using computer€ withinsufficient arithmetic precision or fromgenenating equations which rrove::fit't thedata. Methods of detecting and avoidingthese problens wil-l be discussed. (Authonrsabstract. )

305. OHTAKE. K., KARIYA, M. andITIMUM, T. (f,977) "fhe chenicaL dunability ofPbO-SiO2 glassesrt. Surunary Vol. p.164.

the leaehing behavioun of the su::faces ofPbO-SiO2 and Pb0-SiO2-R20 (R=Na, K) glasses indiluted nitnic acid sol-ution was investigatedby ellipsonetry, buJk solution analysis andinfrared refl-ection spectroscopy. the thick-ness and uefractive indices of the leachedIayen of the surfaces of the glasses duning

'tbe,acid tr€atnent rer€ neasured by Nikon Auto-'ellipsometer'.

The rate ot the leached layer growtbincreased and the ref::active indices of thelayer decreased with the PbO content of thegl-asses. the refi:active indices appnoached toccinstant value except the high Pbo contentgl-asses.

The r€l-ation between the thickness of theleached l-ayen (d) and the tr€atment tinre (t)was expnessed by d=Ctn where n:l- fon the highPbO content glasses,

I/2 < n < I at the fir€t stage andn e; t/2 at the second fo:: the othe:r

glasses.

The two step leaching mechanism was estimatedfrom these resu.l-ts. (Authorst abst:ract.)

spectt:ometry and ion-imaging). Proceedings,VoL III pp.323-31.

The Ion Microanalyzer detects with a highsensitivity the vanious secondary ions :result-ing fnom the bombardrnent of a glass withprimany ions.

It del-ivers the mass spectrum of the ionsemitted by a smafl- region of the speciren(Mass Spectrometny). Conctusions have tbusbeen drawn about the glass hydration phenom-enon, owing to the presence of polyatomic ionscontaining hydnogen.

It gives fon any sel-ected mass and a smal_larea of the specinen, an irnage of the sunfacepar"ts containing el-ements of this mass (IonInages). In this way we were able to show,for a rrmul-ti-layenedtt coppern red gl-ass, thedistnibution of titanirrrn in the forn of layers,and fon a rrfl-ashedrr coppen red glass, thepr€sence of gnains with a high coppet conteDt,in the copper. containing ]ayen. (Authonrsabstract. )

9$. WILL, G. and SCHAEFFER. H. (1977)I'Tnitium tr,acenmethode zur Ltntensuchung denReaktion von.Wassendampf mit einen Na2O-CaO-SiO2 glas" (Tritium ti.acer: nrethod foi theinvestigation of the reaction of water vapourswith an Na20-CaO-SiO2 gfass). pnoceedings,VoI III, pp. 341-350.

The tritium tnace:: method is adapted forthe detesnination of the penetration profileof water in glasses. It al-lows a residualactivity to be measured, if after layen-by-Layer r€trFval- of the sample su!'face therrennining activity of the tritium (B- emitten)which has diffused in is ascer"tained.

The diffusion exper"iment was carried. outessentiall-y at temperatur.es below the g-Lasstnansfomation point Tg, for vanious watenvapoun pa::tial pnessures (applied usingtritiated water) with a sodl-t_ime-sili-a glassof wt.% composition 15.81 Na2O, 9.98 CaO,73.83 Si02.

The rneasuned tnitium diffusion profileexhibits a short-t:ange and a long-naige pant

a (1977)

or the study of glasses by mass

so that an interpnetation using a constantdiffusion coefficient is not possible. Onthe basis of two independent diffusion puocesses,two differ€nt water transpont mechanisms can'be evaLuated. The resuLts lead to the con-c-l"usion that in one case the watet: breaks upthe gl-ass network, i.e. gives rise to Si-OHgl"oups by spl"itting Si-O-Si linkages, and inthe ottrer case lt undengoes an ion'exchangepnocess with the l{a ions in the glass. Tbedependence of the water transport on tenper-atur€ and on water vapout: pantial pr:essune isdiscussed for the two mechanisrns. iAutho::srabst::act. )

Les Dossiens de .l-rAnch6ologie, No.26(.Ianv. - Fdv. L978) is a special issue entir,elydevoted to stained glass and its pnoblems,histor:ica.l- and technical. It is a venitablemine. of information and it contains twelvearticl-es which are abstracted below (Nos.308-319).

308. ANON (1978a) I'Lronigine etl I evoGfion-Efr-vitrail t' pp. 8-10.

This is a generaL article on tbe histonicaldevel-opment of sta,ined glass windows, wittrsections on: the discove::y of glassmaking;the first r^rindows; Romanesque windows of thel-2th centuqi; the grand period of glasspainting in the L3th century; the glassnaker€of the ll+th centurS/ with theit: inheritance oftwo centuries of tradition; and the l-Sthcentury with the innumerab-l-e techniques whichfol-lor,red it. (Abst::act pr€pared by Roy Newton.)

309. 4I9I (1978b) ilLes vitraux de Fnance",p.}}.

This page displays a map of Fnance, showingthe locations of 56 centr€s having stained glassof the L2th to the 20th centunies, i.e., 15 ofthe 12th century; 34 of the l-3th; 29 of the14th; 24 of the lsth; 24 of the 16th; twowith windows of the l-7th century; and one(Nancy) having windows dated to l9OO. (Abstractprepared by Roy Newton.)

310. BE,TTEMBOUJ{GT J.M. (1978) trD6gnadationet conser.vation des vitraux ancienstr, pp.I02-l-l-.L, with l-2 il-l-ustnations.

This papen summarises the scientificaspects of the problems of deter.ioration andconsenvation, recafls what we know about theprocesses of decay ald summanises the attemptswhich have been made to pneserve ancientstai.ned glass. (Abstnact prepared by FnangoisePerrot. )

3l-l-. BEUCHFR, yoniqug (f978) I'Les venni€resdu choeun dtEvreux. Ltinfluence de Par"is auXIVdme si€cLert. pp.63-75, 17 ill-ustnations.

the new chancel of the cathedra.l_ at Evreuxwas rebuilt between I3OB and l-318, ard theupper windows were glazed fnom 1318 onwards.the author has made a study of the eightwindows having ta]l figures and donors, andshe discusses her nesearches to identifv thevanious d.onore, particulanly Regnault dl l,loLins.Hen stylistic analysis leads her to date thevanious glazing eampaigns as fol-l-ows:- l-31-8-1325, first gJ.azing of the apse; 1325-L330,glazing of the choin; l-330-1340, secondglazing of the apse. This stylistic studyr€veaJ-s how there ar€ clear connections with

Jean. Pucell-ers Par:isian workshop fon pnoducingnt'irilE-triiies, and al-so with par,is'ian sc;]pturc.(Abstract prepared by Frangoise Pe:rrot.)

3I2. BRISAC. Catherine (l-978) nlapeinture sur: verre I Lyors au )(IIe siecle et aud6but du XIIIe siBcl-ert, pp. 38-49, 15 itLus-trations.

lhe authon discusses the main dinectionstaken by glass painting in Lyons at the end ofthe l-2th and beginning of the L3ttr ceDturies.Pon her detrpnstr.ation, she uses the glass inthe l-ower windows of the easterrt pant of ttlecathedral of St John. the oldest panels aredated to a::ottnd l-190 and iLlustnate the lifeof St Peter. Despite their bad state ofconservation, their iconography and 6q/]e showa strong Byzantine influence, whidl alsoappearls in other works of ant in this area.Ihe seven lower windows of the Chancel consti-tute another group by which one can fo.Ilowthe deve.Iopnent from the 12th to the j-3thcentur5i. The author concl-udes that four.gindows portray the Redemption, the Historyof St Lazarusr St John the Evangelist, andSt Cypnian of Canthage (and not to tbe livesof the founder€ of the Church of Lyons, as hadpr€viousl-y been bel-ieved) and they stil-l showvarious Byzantine' chanacteristics. On theothe:r hand, the Infancy of Ch::ist, ttle Historyof St Stephen (1215-1220) and the life ofSt John the Baptist (later than 1226) show thatLyons was also open to the influence of the a!.tof nonthern Fnance whieh at that tine cou.Ld bedescr:ibed as the most progressive swLe of art.(Abstract pnepa::ed by Fnangoise Penrot.)

313. FOY, Danieb- (1978) 'rles venrestrouves dans les fouil-]es archdologiquestr,pp.144-122, 12 ill-ustrations,

Many fragnents of window glass have beenfound in excavations. For the south-eastelTrpart of Fnance, they are. now the evidence fon,the gl-azing of many Romanesque and Gothicchurches. The autho:: describes fragn€nts ftqnSt Victor of MarseiLles; from Ganagobie;f::om Psal-modi; from St Fel"ix of Montceau;and fnom Avignon, thus denonstrating theimportance which this place had during the14th centuq/. (Abstract prepared by FrangoisePenrot. )

314. eero.g&!ALr_lf*re",ls.. (f978) "ASaint-Sul-p-i.ce de faviBres, des vj.tre,ux tCmoinsde llart panisien au terrrps de S;rint Iouisrr,pp.5O-62, l-4 ilLustnations.

The sma1l village of Saint-Sulpice deFaviSres, to the south of Paris, bas a cbunchwhose importance can be explained by a famouspilgrinage in the Middle Ages. This beautifuJ-chunch, rebuilt around 1245, stiLl r€tainsthree stained glass windows; finst, a grisaiflewindow (ca. 1260) has naturalistic foliage andit seem$ to be one of the oldest e:rampLes ofthis type of deconation. Secondly, the eastwindow which now contains p€mels fron th!'eewindows, a Passion window (f235-1240), a Lifeof St Sulpice (f235-1240), and two scenes fromthe Infancy of Ch::ist (ca. 1280). The thirdwindow, devoted to the Life of the Virgin andto the Infancy of Christ, is by fan the rostinteresting; its iconography is honogeneous,usiirg several apocryphal sources. Its styleis nelated to the Parisian style which one can

13

see in il-lutrinated manuscripts. It is a uniqueexample of monumental. decorative ant of thispeniod (ca. 1270). (Abst::act pnepared byF::angoise Penrot.)

915. GRODECKI, L. (1978a) I'sauvons 1esvit::aux ancienslrr, pp.J-2-25, 2O iflust::ations.

In this intrrcductoly ar.ticl-e to th€' vofunethe author draws attention to the poot stateof conservation of the stained glass andemphasises the weak points which requireconservationr the decay of the glass and theLeads and the corLosion of the fenrarenta. Hediscusses the va::ious causes of the pr€sentpoor state of the glass and emphasises theharn done by previous restonations. (Abstractp::epaned by Frangoise Pernot.) I\Ftber noteby Roy Newton: this papen is a valuabfe onefor those who wish to have photogr"aphicevidence of the damage to medl-eval windows;these iltustrations show: p.14, br"eakage ofgJ-ass due to weak stonework; p.17, defonmationscaused by faul-ty stonewor.k; pp.20 and 21, theadditional deterio::ation which occunredbetween 1943 and l-947.

316. GRODECKI, L. (1978b) 'rUne g:randeentr€pnise intesrational-e. Le Cor"pus VitnearumMedii Aevirr, pp.124-125.

this a::ticl-e is a review of the historyand the achievements of the c.V.M.A. since itwas for"med in 1952. (Abstnact pnepared byRoy Newton. )

3l_7. HANY-LoNGUESpET Nicot-e (L978)"Troy6f, h"@.eo_t6r,l-5 iLlustnations.

The author summa::ises he:: study of theoutput fron the Troyes wonkshops duning theI6th centuny by sonting out the var:ious trendsand their specific characterj,stics and ernphas-ising the rofe of Dominique Florentin, whointroduced the styl-e of Fontainbl-eu to thisprovince. She then discusses the ploducts ofthe Gontier workshop, which wai active in theJ-7th century, fi.rst establishing the p::ecisegeneaJ.og/ of this family" based.on archivalevidence, and their: r.elatlons with otherTroyes glass paintens. ltren she tries to sortout the wo::ks painted by each menber of thefamily, especially that produced by Linar:dGontier', one of the nost famous glass paintersof his generation. (Abst::act prepar:ed byFlangoise Per::ot. )

3l-8. LAUIJER,- Claudine, (1978) I'Latechnique du vitrail'r, pp.26-37, "L6'iflus-tnations.

this is a detaiLed articl-e in which theautho:: explains how nedieval glass was madeand how the stained glass windows weneassernbled. (Abstnact prepa:red by FranqoisePer:rot.) Furthen note by Roy Newton: 'thediagnams of the l2th-century fu::nace, and themethods of making crosrn gl-ass and cylinde::glass are panticula::Iy elea::; they should beuseful. as lectune-diagnams .

319. PERR.OT. .Franeoise ( l-979 ) "Chefsdtoeuvre rneconnus de la renaissancel lesvitnaux drf,couenrr, pp.7b-85, .t-2 i-LJ-ustrations.

ALthough the Cheteau of Ecouen is veryfamous, nobody has ever paid much attention

to the parish church in this litt:e village,.riobtlfrof Par:is, though it stil_I retains thewindows donated by the Constable Anne deMontrnorency and members of his family. Onecan stil-l- admire, as if they were stiLf inthe chapel- of the chSteau, the po::t::aits ofAnne de Montmonency and his sons, and ofMadefeine de Savoie, his wife and theirdaughters, and also a port:.ait of his nephew,the Candinal of Chdtillon, donons of thewindows of the choir (1545). In the no::thaisle thene ar€ thnee windows of the sarnequa.l-ity, pnobably a p::oduet of the same wonkshop,whose donors were mainly vicar.s of the par.ish.ltre series is completed by the two windowsdonated by Henri de Iulontmorency in 1587. Thefir:st ser.ies is of very fine quality and theconnections with the styJ_e of Geoffr:oyDumonstien wouJ-d suggest that he rnight havednawn the cartoons fon this glass. (Authortsabstract. )

32O. BRUNGS. M. and MICHELL. R. (1977)"Derei-pmen@ betweeng.Iasses of differ:ent oxidation statesr. GlassTechnofoql 1977, I8, I7+-7,

Commentary by Roy Newton: this technical-paper wil-l- be of inte::est -Lo anyone who wishesto study the effects of col-our changes whictloccun when the state of oxidation of the glassis changed. As was pointed out by Seflner(Abstr:act No.298 on p.f3 of NL No.26) the colourof medieval glasses depends on their" state ofo><idation. These authorE show that sulphundioxide in the gLass also plays a pal:t inaffecting the oxidation-reduction situation.

321. CHARLESWORTH, Donothv (1977) "Romanwindow glass from Chichester, Sussextr. J.GlassStudies, l-977 XIX I82.

Oomnentary by Roy Newton: The specialinter€st of this item is that Miss Cha::Leswor"thfound a piece of cnown window glass in a Romancontext dated to the 4th century. This isveny much earlier than had previously beenthought possible fot: a western origin of suclrgl-ass. Saq)l-es of cast window glass andcvJ-inder window glass wene also found on the

322. DEKO.WNA,,.Mania (l-973) "pnobl-eme del-texistence dtun ate-lier: venrier" d Szczecinau haut moyen dgerr. (Ihe problern as to whethera gl-ass workshop existed at Szczeein in theninth century.) Ann..6e Cong. 3$roc., -Lntemat.Hig_t, dq Verne, CoLogne. Jul"y 1973. DD.t43-f58.

Commentary by Roy Newtont This is animportant papen from the point of view of thehistory of the technologr of glassrnakingbecause the authol: found some high-potash glasson a site of gth century date, the fi::st tinrethat such an earl-y date has been found for thiskind of glass. Du::ing the excavation of themedieval castle of Szczeiin (nea:. the Bafticcoast of PoLand) a gth-century habitation sitewas found with pl-enty of evidence that inon-wor"king had been carnied out there. But ther€wer€ two yellow gl-ass beads, a fragnent of aglass vesseJ-, two pieees of brcken glass andtwo very smaLl c::ueibles with a l-ayer of glasson them. The fnagment of the vessel_ contained58% Si02r 19% K2O, 99o CaO, etc, rather like amedieval glass. The glass on the crucibJ-eswas also a high-potash material- and the author

nakes a nunber of comparisons, of a chernicaJ_nature, between these glasses and others flomCo::del, Kiev, HaliE, Cracow, etc, and concLudesthat therc are no verSr cLose par'a'll_els betweenhen glasses, these other,finds, and the cor4lo-sitions of the ashes fr"om wheat straw or thetnurks of beech tr€es (which corne nearest incomposition to hen gJ.ass). Ttre comnentatotbelieves, however', that the glasses fnom hercnucibles were heavily contaninated by thesolution of refnactony naterial and that thispart of her. exercise waa certain to fail_;hor'even, hen glass fr.agments are undoubtedJ-yhigh-potash Jinre-glasses and of an exceptionallyear.Ly date, so that her papen is an inpontantone .

There is, however, sorne doubt as towhether the glasses were nade on the site fronsand aod pJ-ant ash because the crucibJ.es areso ve!.y srnal1, being only 35 rnm in diarneter!However, these snal-l crucibles couLd have beenused for ne-wonking culJ.et made at aone otherplace, as yet unknown.

the two yellow beads have quite a differentcomposition, being high-lead soda glasses(3O-q0% Pbo, 5-1OB Na2O) and seem to be lmporta,perhaps f:rom the l,evant.

323. GOLDSIEI.N, S.M. (1977) riPo:rgeniesand r€productions of alcient glass in Corning",J. Gl-ass Studies. l-977. XIX. 40-62.

The Corning Museun of Glass has beenmaking a special col"J"ection of fo::geries, andreproductions, of ancient glasses so thatscholars can study the methoals used by moderrrr.ronkers to copy or alter ancient glass objects.(Abstnact prepared by Roy Newton.)

324. GROSE. D.F. (1977) "Early blownglassrr, J. Gl-ass Studies, Ig77r -4,, g-Zg.

Corfipntary by Roy Nevrton: This is aparticuJ"arly interesting papen fon anyone whowishes to learn what is known a.bout the datewhen glassblowing was invented.. The authondiscusses a gr€at deal of evidence of all-kinds, especial-Ly r€cent diseovenies in Is::aeJ-in L961 and 1970, but also wall-paintings inPornpeii, etc, to throw more l-ight on thepnobiem of when and wher€ glassblowing wasinvented. He bel"ieves the date is rrow as ea:r,Iyas 40-30 BC, and that the invention took pLaceat an inland site (penhaps IsraeL), rather rhanon the Synian-Phoenecian coast.

325. HAN..,ver€na (f973) "I€s relationsvenri€res entre Dubliovnik et Venise du XIVeau XVIe siBc.lett (Rel-ations between glassworksin Dubyovnik and Venice fuom the _l_4th to l_6thcenturies), Ann. 6e Cong. ASSoc. Internat. duVerne. ColoEre, JuIy 1973, pp. 159-168.

ComtentarSr by Roy Newton: this papen ispacked with detaiL denived duning the lastten yealrs by studying the anchives at DubrovnikShe shows that ther€ were exceedingJ.y closeLinks with Munano, with many reconds of impoootsof glassi the rnignation of rnaster glassblowerefr€n I'lulrano to wo:rk at Dr:brovnik; and the useof tenminolory which vras denived f?om that usedat Murano. Ttris is a welL-documented papen ofgr€at inter€st to anyone concerned with suchhistorical devel"opments.

326. HUMER. ,J.R. (L977) "Glass fnagrentsfFc{rr, the. Vi carage garden, Bni:<nonthrt r'Joury.Bnit. Ar.ch. Assoc., 1977r pp. 104-107.

this is part of the Report of the BrixworthAnchaeologi ca.I Re searctj Conmi ttee excavationsat Brixworth Saxon church. Ihentyfouri frag[€ntsof vessel-- and window-gl"ass were discovered,9 of which had heavy iocrustations and wer€considered to be medieval but the neuraining15 were urone durable and ar€ eonsidered to beof Saxon o::igin like those at Jamow,Monkwearnputh, Escornb, Repton anal Harr*ih. ltrecoLourE of the 15 pieces were bLue, J-ightgr?een, erer€ld green, yellow and brown; sonepieces were grozeil. (Abstract pr€par€d byRoy Newton.)

327. MARECHAL. J.R. (1973) tEquiperentminimurn de labonatoire poun ltanalyse chirniqueet apectrpgnaphique des'venl€s du Moyen Ageet dtude de J"eun alteration par exalnen aumicroscope du lane rnincert (Itre rninimumlaboratorX/ egui.prnent needed for chemicaJ. andspectnographic analyses of rnedieval gl-assesand the micr,oscopic study of thein weather:ing,using thin sections).

3,pp.299 - 307 .

The authon descnibes ttre pr.inciples ofchemical analysis of glass, using various typesof equiprent and indicates what could be boughtfon different amormts of money when setting upa laborator5t. (Abstnact p'nepared by Roy Newton.)

328. PAUL, A. (1977) "Cheni.cal dunabilityof glasses; a thermod1marnic approactr", {.@I9I.Sg!. , tgZZ ].2, 2246-2268.

Comrnentary by Roy Newton3 Ttris paper byDr, Paul, who has contributed several usefulitems to eanl-ier. News LetterE, is one thatgJ-ass scientists have been waiting for becauseit presents, in an easily readabLe mannen, amasterl"y review of the present state ofknowledge of the dunability of glasses. Ihetitle of the pape!'is nathe:r forr[clable butrpst of the text is entirely readabLe and thetherrnodynanri.cs can stay in the backgr.ound for.those who need them as an expJ.anation of theexpdrimentaJ. resuLts obtained. lle shows $rhythe extnaction of sil-ica fr.on glass. by aqueoussolutions, increases when the l-ine content ishighe:r than 1O nol% as a resul-t of rnicrophaseseparation in the g1ass. Lirne is J.eached fromthe sur.face of the glass to a depth which issnaJ.Ler than that fot: soda and siJ.i.ca and itis not yet clean why this is so, although sornenypotheses have been put for? ard to explain it.The nelative durabilities of glasses can dependma:rkedly on temper€tur€, for exampJ_e, rlpstglasses at 98oC have on-ly about one thind ofthe dunabiLity which they possess at 6OoC butglasses containirrg Bao becorE even 1ess durableat 98oCr having only about one-eightb of thatat 60oC. He also rremarks that the cunrentlyaccepted idea, that protons enter the glass anexchange fon alkaLi ions is probably wrong andit is nore likely that the hydroniurn ion (H3O+)is the one which enters the gfass; aJso, freewater molecuJ-es can occun within the Leacbedsr.rrface J.ayen.

329. SPITZER-ARoNSON. Uantha (I977b)'rCalculs sun images X de conrosion des vitraux,

des taux dreLimination par 6J.6nent, entr€ Lasunface corodde et l-e venre intact sous jacent'l(Calculations based on X-nay images. of ther{eathering of g]ass, including the extractionof different elenents fnom the cor,::od.ed glassand the nearby intact glass). Compt. Rend. Acad.Egj.:r.!g!g, senies c285 (rr Jffi6ffF;.---4i.-43.

A new, non-destructive, nepetitive, methodfon studying co:nnosion - oJ.d co:rrosioo and thatwhich was alnost stopped under the vanious oldstained glass nestorati.ons done in Eu:rope - ispresented. It all"ows us to evaLuate theelimination rate of the elenents and companethe successive rneasures penfonrned on a specialsanple senies. ltre choices are described:of the electronic trreatment done on the digit-alised X-irnages; of the various iso-concent-ration sur:faces by eLement; and concerningthe stonage of the signals in a npmory.(Authorts abstnact.)

330. sPrrztR-ARoNlgIr-4gllb (re77 c)"ta r€fartiffiivre,retrouvde d cal.cuL6e daris centains vitnauxrouges addidvauxrr (The oniginal distributionof copper, both as formd and as calculated,in centain redieval red slasses). Cornot.Rend.Acad.Sci., Panis, Senies-C285 (J-O d;T1j577fpp.269-272.

the distnibution cunves of Cu, Zn. Sn inred muJ.tiJ.ayer€d stained glass of the MiddJ.eAges, their dispanities and thein correlations,ar€ expJ-ained by the diffusion of Cu in thehot gl-ass, wheneas Zn and Sn ar€ not diffusedin these conditions. The computation of thediffusion allows us to find the concentrationof Cu at the beginning of the fabnication ofthe J.ayers with Cu and gives indications onthe composition of the bnasses used. (Autho:rrsabstnact. )

Coment by Roy Newton: This interestingpaper by Dn Spitzer-A:ronson reises sonefascinating r.manswered questions. the diffusionof the copper, and the non-diffrision of thetin and zinc can zeadily be understood becausethe copper wiLf be plresent as Cu'O, and thecu* ions are small'and nrobile, l-ike Na+ ions.in contrast to the Sn2+ (pnobably Sn4+) ions.and the Zn2* ions, wher.e the nretil-oxygenbonding is highly covaJ.ent and the change onthe rnetaL ion is high, nnking them imnobile.But the bands of ned coLoul" shown in hen Fig.Iare genenally where the Sn and Zn ar€ notpresent! In conrespondence with ne on-Fhispoint, Dr Spitzen-Anonson has suggesteil thatthe r€d coJ"our develops wher,e the cg4qel:rlt qtiongredient of copper is greatest, luT-5ffi6--possibility is that sone eLernent in the basegLass may have to be plresent, in associationwith the copper, in onden to devetop the r€dcoIour3.

33L. STMUSS, J. (J.977) (Use of thearchaic wond rrrnetalrr for glass.) J.GJ.assStudies.1977 XIX 186.

In a Letten to the Editor.of the JounaL,the author deplores the use by a:rchaeologistsand art histonians of, the term rrmetalrr to rpearglass, because it is ambiguous and misleading,(Abstr:act p:repared by Roy Newton.)

1E

332. WALTERS. H.V. and ADAUS, P.B. C1975).!rEff.e,.9ts of hurnidity on the weathening ofglassr'. J.Non-Crvst.SoLids, J-975 19 183-199.

the authonsf abstract is:- The weatheringof 26 gJ.ass compositions under static conditionsof 30%, 5O%, 75%. 90% and 98% rel"ative hurnidity(RH) at 5OoC and a cycling condition between77% and 98% RH at 50oC. The cycJ.ing conditionwas found to be less severe than static 98%RH. The effect of hurn"idity level on weatheningwas studied and showed that water adsonptionincreases with time arid humidity, whereasalkali generation inereases with tinre, but notalways with hunidity. Significant weatheringoccur:s for: some glasses at 30% RH with tlrequantitative effect being alnost as great asat 90% RH. Visual- weathening was observed fonsome glasses when the J-evel of genereted alkaliwas less than 0.5 W/cmz,

Various techniques fon evaluating theweathe::ing of glass under humid conditionswere investigated. Visual appeardrce wasjudged to be the best evaLuation method forroutine weatie::ing tests. It'repr€sents theeffect of nost concern and is sufficientlypr,ecise. ELectron nicnoscopy, neasunement ofsonbed water and alkal-i gener?ated ane pnin-cipally used for neseanch studies. Weightchange and haze rneasunernent Lack sensitiviryand repnoducibiJ-ity. A standard test wasdefined. The conditidrs ar€ 98% RH at 50oCfor" 12 weeks. the visual. ranking systen wasused. The g.l-asses wene generally nanked inthe same onden by the vanious eval"uationtechniques.

Additional corunentary by Roy Newton:This is an important papen fon those who areconcerned with arranging the environtlpnt ofwindows for their best ccrnse::vation; fonseveraJ- reasons. First, the authors find thesane resuLts aa those discussed in News LetterNo.24, Section a.3 (p..]0); that repeatedcycling of condensation is J.ess aauaging thana continuous high hu:nidity, despite afL thetheoreticaJ. arguments that condensation,folLowed by drying, rrshouldlr build up analkal-ine layer on the gJ.ass. It seers thatthe periods of condensation pnoduoe a trwashingtl

effect, ther€by rennving the aJ.kaline proiluctswhich are t'supposed't to accumuJ.at6. 0n theothen hand, continuous high hunidity can J.eadto the accumul-ation of alkal-ine productsr asis drarnatically shown by their Fig.l-9 (p.196).The sbcond important point is that some ]eadglasses will show senious weathening at onLy30% RH, and these findings must be givencar€ful consideration in connection withnuseun atrnospher€s used for storing teadgLasses (eg Ravensoroftts glasses). Ihe thirdpoint of speciaJ. inter€st is that high RH

vaLues (above 9O%) cause the surfacea of sorlpglasses to absonb excessive amor.rnts of water.

333. WE\S.ER. Fe::dinand, (f,978) ItZehntes

Intemationales Colloquium des CorpusVitrearum Medii Aevirr, Kunstchronik l-978 3J-(2) ss-se.

this is a shorit accormt in Gernran of thel0th CVMA Colloquiurn, with enphasis on theart-histonicaL papers.