demystifying cold and frozen storage - dhpsnydhpsny.org/sites/default/files/pdfs/dhpsny cold...

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Demystifying Cold and Frozen StorageBarbara Lemmen


A decrease of 10° doubles the lifespan of organic objects

Benefits


Benefits

Gains years of useful life for original objects

Provides low temperature and low humidity

Buys time to plan and raise money for preservation

Often costs less then digitization

Decreases use and browsing

Best preservation method for unstable materials


Temperature Ranges

Room Temperature 70°F / 20°C

Cool 54°F / 12°C

Cold 40°F / 4°C

Frozen 32°F / 0°C

Sub-Zero < 0°F / -20°C


Concerns

Ice crystals forming

Thermal shock

Dimensional changes

Mechanical damage

Risk for condensation

Limited access


Concerns

Ice crystals forming

Thermal shock

Dimensional changes

Mechanical damage

Risk for condensation

Limited access

Research shows that these are not an issue

and/or

can be addressed with proper procedures


Costs

• Initial purchase and installation of equipment

• Vapor-proof packaging materials + labor costs

• Storage furniture

• Energy

• Security

• Maintenance

Courtesy of the NPS


5 Stages

1. Identify and Prioritize Items

2. Prepare the Collection

3. Select Equipment or Facilities

4. Access the Collection

5. Monitor and Maintain the System


Prioritization

Material

Condition-- Acceptable loss -- Rate of deterioration

Value-- Research-- Cultural-- Future earnings potential-- Obsolescence factor for AV

Access

Budget


Do you have?

Earlier Film Base Photographic Materials

Color Photographic Materials

Inkjet Prints

Poor Quality Paper and Books

Audiovisual Media


Film: Black-and-White and Color


Film

ISO Medium-term Storage Conditions =

ISO Extended-term Storage Conditions =https://filmcare.org/storage_categories


Photographic Prints: Traditional and Digital


Courtesy IPI

Photographic Prints


Audio Visual Media: Magnetic Tape

Courtesy of Wikipedia

ISO 18933:2012Polyester and acetate base


Audio Visual Media: Optical Disc Media

http://www.yourdictionary.com/optical-disc

ISO 18925:2013


Paper

NISO Standard TR01-1995 Paper Records: 35-65°F (2 - 18°C) and 30-50%

Brittle wood-pulp paper – approximately 1850-1950

Courtesy of Middlebury College


Exceptions for Frozen Storage

CDs and DVDs

Collodion negatives

Instant prints, e.g. Polaroids

Additive color processes

Cased photographic images

Bound volumes?

Courtesy Library of Congress

Courtesy swiss-miss.com

Kuriositas.com


5 Stages







Organization and intellectual control

Critical for retrieval

Process all materials

Create an inventory, labels, vault / freezer maps

Reformat/digitize

Courtesy of Henry Wilhelm


Organization and intellectual control

Critical for retrieval

Process all materials

Create an inventory, labels, vault / freezer maps

Reformat/digitize

Place high priority itemsinto cold storage

ASAP and digitize

when accessed



Rehousing

Replace enclosures and boxes

only if unsound, weak, or brittle


Relative Humidity (RH)

As the temperature drops, RH increases –- water must be removed to maintain a low RH



If a cold object is brought into a warm room, it crosses the dew point (100% RH) and condensation occurs



If a cold object is brought into a warm room, it crosses the dew point (100% RH) and condensation occurs

https://i.pinimg.com/originals/cf/7b/00/cf7b00d574e923171f65ea644e19d5e2.jpg


Vapor-proof Packaging

Creates a microclimate around the photographs, to control RH

Side benefits Prevents condensation during retrieval Protects from leaks or mechanical failure in storage Protects during handling while frozen

Cons Upfront cost Labor intensive Ongoing cost and time for repackaging after use Prevents browsing


Vapor-proof Packaging Components

1. Photographs in box

2. Moisture Buffer- minimal trapped air- filler materials

3. RH indicator cards

4. Two vapor barrier bags


NPS Design with Static Shield Inner Bag

1. 2.

3. 4.Courtesy of NPS


National Park Service Cold Storage Website

http://www.cr.nps.gov/museum/coldstorage/html/intro1_1.html


Critical Moisture Indicator (CMI) Design

Two heavyweight polypropylene Ziplock bags Desiccated matboard sheets = moisture trap Create 2 microclimates

“Image Archive Freezer Kit”

$25

Home-made CMI Lower cost - purchase components separately Increased flexibility in size and shape of package

Courtesy of Metal Edge Inc.


5 Stages







5 Stages



3. Select Equipment or Facilities Leased Commercial Storage Space

Free-standing Unit

Walk-in Vault or Storage Room

with Humidity control – “Active”

without Humidity control – “Passive”


Leased Commercial Space

Permanent or temporary solution

Expensive over time

Reduced access

Look for vendor with a good track record and securityNo climate controlled storage available for nitrate

Courtesy of Iron Mountain

Sub-zero vault of the Corbis Bettmen at Iron Mountains/National Underground Storage Vital Records Facility - Courtesy of Henry Wilhelm


Free-Standing Refrigerator or Frost-free Freezer

Pros Typically 35°F (2°C) or 0°F (-18C) Fast and easy to buy and maintain Can operate in collection area Models hold 20 to 72 CF Multiple units can be used Cost-effective for < 150 cubic ft

Cons compared to vault Sealed packages control RH Shelf space limited and less flexible

Courtesy of NPS


Features to look for

Commercial or Scientific Large capacity Lock from the outside Alarm (will be supplemented) Temperature read out Adjustable, sturdy wire shelves Low heat generation Quiet operation

Images courtesy of NPS


Free-standing Refrigerator

Color negatives and slides at theMonmouth County Archives

Courtesy of Gary Saretzky


Loading the Refrigerator or Freezer

Labels and humidity indicator cardsfacing out

Maximize available space

Distribute the weight evenly

Adjust or remove shelves/drawersas needed

Do not block the cold air vent inside

Be sure that the temperature hasstabilized and the unit acclimatedfor 24 hours

Courtesy of Sarah S. Wagner


Cellulose Nitrate Film

“National Fire Protection Association (NFPA) 40”

Addresses flammability of nitrate movie and sheet filmduring storage and handling

‘Extended storage’ cabinet required for 25 to 50 lbs-- can be a flammable materials storage freezer (FMSF)

Note: Maximum 50 lbs film per freezer

Freezer can not be in thesame space as collections

FMSF gives out much more heat than FSFFF

Courtesy LabRepCo


Walk-in Vault vs. “Freezer Bank”

150 Cubic Feet is the tipping point

Vault Larger capacity is generally more E efficient than multiple, small

units You can avoid packaging

Multiple Units Noise and Weight factors Costs can escalate > 10 units Energy draw for many units

may be higher, requiring added wiring May need external cooling for heat load



Walk-in Vault

Freezer typically 0 - 5°F (-18 – 2°C) Refrigerator typically 35 - 40°F (2 – 5°C)

Pros Can have RH control at 35%, or not Cost-effective for collections > 150 cubic Ft. or anticipated to grow

More flexible and efficient use of space Custom and standard sizes Can reuse existing and/or flexible shelving systems

Cons Construction and maintenance complex Cost high, especially with RH control Requires dedicated space Packaging/bagging for warming or vestibule may be needed


Walk-in Vault



Vault with Humidity Control

RH controlled for entire space

30 to 40% RH common

No packaging necessary Retain objects in original format, housing, framing Browsing and item level retrieval improves access No problems with faulty packaging No preconditioning – objects will adjust to vault RH

Air filtration for volatile organics common

Courtesy of the National Park Service


Freezer within Cold Vault with Humidity Control

The Museum of Modern Artfreezer 30-35F/35%

refrigerator 50F/40%surrounding room conditions 70F/50%

Courtesy of the Henry Wilhelm

Courtesy of Amber Kehoe


Vault/Room without Humidity ControlAKA Simple Freezer Vault

No RH control Less expensive Less common

Gasketted-sealed cabinetsRH controlled with microclimate created within the cabinet



5 Stages







Accessing the Collection

Retrieval

“Time out of storage”

Staging/Acclimatization

Reconditioning/RepackagingCourtesy of Henry Wilhelm


Time Out of Storage

IPI “Storage Guide for Acetate Film”


Staging or Acclimatization

Bring cold/frozen material to room T and RH and reach thermal equilibrium

To prevent condensation and uneven drying

Time required depends on multiple factors

Can be accomplished in several ways....

* 24 hours is standard

Courtesy of the National Park Service


Warming Procedure

1. If unpackaged, place object/box into sealed plastic bag and squeeze out excess air

2. If transporting outside the building, place into an insulated container

3. Move to a room temperature location

4. When it no longer feels cool, wipe off excess moisturewith a cloth and open bag

Courtesy of the NPS


5 Stages







“An Ice Scientist’s Worst Nightmare”

https://www.nytimes.com/2017/04/11/climate/ice-cores-melted-freezer-alberta-canada.html?mcubz=1


Monitor the System

Malfunctions may lead to

Loss of RH control

Heat build up

Water

Combat with:

Redundant systems

Alarms

Periodic Inspections


Alarms

REF/FREEZER Temperature alarm

wireless or wired into system

VAULT Fail-safe automatic shut down systems and alarm

if T or RH exceeds upper or lower limits

Standing water detector for condensation



Periodic Visual Inspections

RH cardsCheck when unit first stabilizes, then every 3 monthsOuter card < 60% and inner bag < 50%

Check monitoring devices

Check freezers for frost build up

Check air vents are not blocked

Maintenance


Important Paperwork

Keep on the exterior of equipment

Map of contents

Inspection Log

All procedures

Equipment manuals

Emergency numbers



Summary

Preservation Requires Freezing StorageEarlier Film Base Photographic MaterialsColor Photographic MaterialsInkjet Prints

Preservation Requires Cold StoragePoor Quality Paper and BooksAudiovisual Media

QUESTIONS?

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