18 J o u r n a l o f A r c h i t e c t u r a l C o a t i n g s / M a r c h / A p r i l 2 0 0 7

Special Report: Antigraffiti Coatings

They say beauty is in the eye of

the beholder.

In the case of graffiti, however,

the audience of beholders who see

the beauty in this genre of “art ”

may amount to very select compa-

ny—the “artist” himself, perh a p s ,

along with a few of his closest associates, admirers, or, possibly, rival practitioners.

For the uninitiated—mainstream society, essentially—the great body of work of “taggers”

remains unappreciated, misunderstood, or simply reviled, no matter the skill, inventive-

ness, or daring involved in its cre a t i o n .

S u re, there are the odd exceptions—specially designated areas where graffiti art-

work is permitted, even invited. But most of the graffiti that greets the public

eye—whether it’s splashed across building facades, highway noise barr i e r s ,

bridge abutments and spans, rail cars, or any other surface that serv e s

as ersatz canvas—is viewed as an eyesore by all but perhaps the

most charitable of art critics.

Thus, hard on the heels of the graffiti artist comes the

a n t i g r a ffiti army—the crews that labor to re m o v e

the tagging, which is often applied with

highly durable aerosol paints or pow-

e rfully formulated marking

i n s t ruments. And

behind the

Taking aim against tagging

Whether it’s viewed as art or awful, graffiti

continues to be targeted by growing

arsenal of technologies

By Joe Maty, Editor, JAC

f ront lines of the antigraffiti infantry, in the offices, laborato-

ries, and maintenance shops of public agencies and private

companies, chemists and technicians strive to come up with

the latest graffiti antidote—the combination of graff i t i -

repelling surface treatment and graff i t i - removal agent that can

win this war, or at least keep the enemy in check.

The conventional wisdom holds that the magic bullet, or

universally effective antigraffiti weapon, has not been

devised—at least not a solution that would prove economically

viable in the marketplace, where cost remains a factor. Still,

some highly effective materials and methods have been devel-

oped by coatings and chemical companies, and continue to

e m e rge in response to the needs of users. (See accompanying

d i re c t o ry of antigraffiti products.) These customers, often pub-

lic jurisdictions with limited budgets and work forces, are n ’t

asking for much—just a cost-effective treatment system that

allows graffiti to be easily re m o v e d .

P romising technologies and techniques—if not the elusive

silver bullet—do appear on the scene on occasion. Just ask To m

S c h w e rdt, a paint chemist with the Texas Department of

Tr a n s p o rtation, who talks enthusiastically about a silicone-

based coating that shows the potential to generate a seismic

shift in how the department handles graffiti along highway

rights-of-way in the Lone Star State.

S c h w e rdt is helping to shepherd a new perf o rmance specifi-

cation through the Texas DOT that will facilitate use of this

new technology. The product that led to the new specification,

Si-Coat 530, is made by CSL Silicones, a relatively small com-

pany based in Guelph, ON.

The product is a one-component, clear coating that has

p roven in field testing to allow removal of graffiti with just a

cold-water wash employing relatively low pre s s u res of 1,500

psi or less, Schwerdt says. Schwerdt, lead paint chemist in the

Materials and Tests unit of the DOT’s Construction Division,

reviewed the Texas DOT’s evaluation of the product in a pre-

sentation at PACE 2007, the Paint and Coatings Expo, in

F e b ru a ry in Dallas.

Permanent or sacrificial?The CSL Silicones product is a type of antigraffiti coating classi-

fied as permanent, or “non-sacrificial,” meaning it is applied to

J o u r n a l o f A r c h i t e c t u r a l C o a t i n g s / M a r c h / A p r i l 2 0 0 7 19

(Facing page): A “tagging” incident shortly after the opening of the Cesar ChavazLibrary in Phoenix sent library authorities on a search for answers on antigrafittistrategies. The defensive measure they settled on was application of a penetratingsilicone rubber-based antigraffiti coating, Series 626 Dur A Pell GS (GraffitiShield), to the building’s concrete block exterior. The product is supplied byChemprobe Coating Systems L.P., a subsidiary of Tnemec Company Inc. Subsequentgraffiti markings were effectively removed using a citrus-based cleaner sold aspart of Chemprobe’s antigraffiti product system, the company says.

Taking the fight to graffition multiple frontsCoatings for Industry Inc., Souderton, PA, has developedand marketed high-performance polyurethane coatings forantigraffiti applications for nearly 30 years. The compa-ny's extensive portfolio of antigraffiti applications rangesfrom New York city subway cars, to the exteriors of univer-sity buildings, to countless bridges and other transportationinfrastructure.

(Below): Graffiti is removed from the brick exterior ofhousing in Allentown, PA. The polyurethane antigraffiticoating applied to the porous surface serves as an graffitibarrier and facilitate removal of graffiti with a pressurewash using an alkali-based cleaning agent.

a substrate with the intention of providing a long-term serv i c e

life despite repeated cleaning to remove graffiti. As such, the

p roduct is formulated for durability in exterior exposures and

resistance to specified cleaning methods that are designed to

remove graffiti but not the antigraffiti coating. Such coatings

do not remove tagging that has already occurred, but are

applied to a graff i t i - f ree surface to facilitate removal of subse-

quent marking.

These permanent or non-sacrificial coatings are based on

several major resin chemistries, with silicone- and

p o l y u rethane-based materials figuring pro m i n e n t l y.

Another class of antigraffiti coating, defined as “sacrificial,”

is comprised of products that are designed to be removed fro m

the surface along with graffiti that has been applied to the

c rete block, and you don’t want to have

to use diff e rent (antigraffiti) pro d u c t s .

“And you want something that’s long

lasting—five years minimum, and more

like 10.”

At the top of his list of re c o m m e n d e d

a n t i g r a ffiti products, Zeh says, are pene-

trating treatments based on silicone

c h e m i s t ry. These products may contain a

f l u o ropolymer or fluorofunctional silox-

ane to enhance bonding to the substrate,

h y d ro p h o b i c i t y, and non-stick and dirt -

repellent pro p e rties. They resist water,

oils, paints, and marking materials.

“Penetrating treatments of this type

p rovide antigraffiti pro p e rties but do not

alter the look of the substrate,” Zeh says.

“In general, most of our customers pre f e r

that kind of product, to retain the appeal

of the substrate material.”

Sacrificial, or non-permanent, antigraf-

fiti treatments can prove valuable for use

on facades such as precast concre t e ,

because precast is a relatively inexpensive

exterior surface material where a minor

darkening or gloss enhancement of the

s u b s t r a t e ’s appearance caused by the wax-

based coating is acceptable.

These treatments are lower in per- g a l-

lon cost, but re q u i re reapplication after

g r a ffiti removal.

“They are handy in areas where you

c a n ’t use certain cleaners, such as a bridge

over a stream or river where enviro n m e n-

tal factors come into play, or if the loca-

tion is in an urban setting where the

ru n o ff would enter the storm drain

instead of the sanitary sewer,” Zeh says.

In these situations, capturing graff i t i -

removal waterblast ru n o ff that contains

s t rong cleaning agents or solvents could

p rove costly and would bring enviro n-

mental controls into the picture .

Zeh describes another general classifica-

tion of antigraffiti treatments as film-

f o rming coatings. This group includes

chemistries that range from re l a t i v e l y

low-cost acrylics to higher- p e rf o rm i n g

p o l y u rethanes and epoxies, some of

PROSOCO Inc., a major supplier of water

and stain repellents, coatings, cleaners,

curing and hardening agents, and re l a t e d

p roducts for concrete and masonry, says

specifiers and users should look for a

number of product characteristics when

evaluating antigraffiti treatments. These

include suitability for a variety of sub-

strates—brick, fired brick, tile, stone of

various types, and all manner of concre t e

including poured-in-place, CMU, tilt-up,

and cast-in-place, as well as mort a r s .

“This is important, because you see a

lot of construction where the building

f ront is a nice brick and the rest is con-

coated surface. These coating materials

a re often based on waxes that are easily

washed off with hot water or mild deter-

g e n t s .

A disadvantage of sacrificial tre a t-

ments, in the view of many potential

users, is the need to reapply the coating

following removal of the graff i t i .

Advantages, on the other hand, include

the relatively low cost, the simplicity of

cleaning and removal methods, and a

benign environmental profile for both

the coating treatment and cleanup mate-

rials.

Peter Zeh, laboratory manager for

20 J o u r n a l o f A r c h i t e c t u r a l C o a t i n g s / M a r c h / A p r i l 2 0 0 7

Rolling on the River Walk, and leaving tagging in the wakeThe San Antonio River Walk, the city’s premier tourist attraction, follows the jade-green San Antonio River through a section of the city center, and features uniqueretail shops and nightclubs set amid towering cypresses, oaks, and willows. Butgraffiti had marred the concrete underside walls of the north channel of the river.After a program of painting over the graffiti was deemed unsatisfactory due to anunattractive, blotchy appearance, the city’s Parks and Recreation Department used ahigh-performance clear polyurethane coating system, PermaCoat, supplied byFreda Inc., Angola, IN. The polyurethane coating facilitates removal of graffiti withthe use of PermaClean, a biodegradable, soy-based solution that is allowed todwell on the graffiti-marked surface for four to five minutes. The graffiti then emulsi-fies and is rinsed off the surface. Key raw materials for the polyurethane antigraffiticoating system were developed by Bayer MaterialScience LLC. The coatings can beapplied to concrete and steel surfaces.

http://www.wrmeadows.com

22 J o u r n a l o f A r c h i t e c t u r a l C o a t i n g s / M a r c h / A p r i l 2 0 0 7

which also can be applied to metal sur-

f a c e s .

The growth in popularity of concre t e

c o n s t ruction is driving increased demand

for protective treatments in general. The

a n t i g r a ffiti functionality possessed by

some protective treatments is adding

even more momentum, in response to

the mushrooming graffiti problem mani-

fested in urban areas, Zeh says. For

PROSOCO, the penetrating tre a t m e n t s

based on silicone chemistry account for

the lion’s share of products sold for anti-

g r a ffiti applications. Film-forming acry l i c

coatings and sacrificial wax-based pro d-

ucts re p resent smaller percentages of

s a l e s .

Substrate a key to product choice

In addition to economics and enviro n-

mental factors, a key issue in determ i n-

ing which type of product to use is the

substrate. A non-porous substrate such as

metal, some types of stone, and even

brick to some degree, does not lend itself

to the use of penetrating silicon-based

t reatments. A film-forming acrylic makes

sense where a slight appearance change

and lower level of durability and clean-

ability are acceptable. Relatively inex-

pensive sacrificial treatments are re c o m-

mended for some situations, but are

m o re maintenance intensive. In some sit-

uations, owners simply engage the ser-

vices of outside contractors that apply

the sacrificial coating and clean off sub-

sequent graffiti on a regular basis.

The diff e rent technologies also vary in

their effectiveness in preventing “ghost-

ing”—the graffiti shadow sometimes left

behind to haunt the owner when the

tagging is removed by cleaning. In Zeh’s

v i e w, penetrating silicon-based tre a t-

ments are most effective in warding off

this “ghosting” eff e c t .

In the case of the silicone tre a t m e n t

that has won favor in the eyes of the

Texas DOT, a new, more precisely targ e t-

The show goes on, but graffiti exits the stageThe detrimental effects of graffiti were driven home in “dramatic” fashion during amultimillion-dollar restoration program for the historic Fox California Theater in SanJose, CA. Construction workers arrived on the job early one morning to the sight ofa black blotch of graffiti 100 feet up on the back side of the building. Three lettershad been spray painted six feet tall and 10 feet long on the concrete wall. Themarkings were blasted off, at a cost of $5,000 and abrasion to the concrete sur-face. In addition to treating the prized limestone exterior of the building with a pen-etrating water repellent, the building owners took an additional step, contracting forapplication of a “sacrificial” antigraffiti coating to the porous limestone—PROSO-CO Inc.’s Eraser® Graffiti Barrier S. The coating prevents graffiti media from pene-trating porous surfaces; when marking does occur, the coating is washed off, takingthe graffiti with it. In addition, the non-toxic, no-VOC sacrificial coating requires noharsh solvent cleaners or paint strippers for removal, an important benefit due tolocal environmental regulations that restrict the use of such agents.

http://www.kioncorp.com

24 J o u r n a l o f A r c h i t e c t u r a l C o a t i n g s / M a r c h / A p r i l 2 0 0 7

ed specification has been crafted to

reflect the attributes of this technology,

S c h w e rdt says. This language is spelled

out in a description of a “Type 3” anti-

g r a ffiti treatment—a coating that is per-

manent but cleanable with low-pre s s u re

water spray.

The proposed Type 3 antigraffiti coat-

ings specification, titled DMS-8111,

would take its place alongside existing

Texas DOT specifications that addre s s

the use of antigraffiti sacrificial tre a t-

ments (Type 1) and permanent tre a t-

ments (Type 2). The key diff e rence for

the new, Type 3 treatment is the “water-

cleanable” provision. As a rule, perm a-

nent antigraffiti coatings re q u i re cleanup

with agents such as strong detergents or

solvents.

S c h w e rdt says the proposed specifica-

tion is awaiting final approval by the

The exterior of the former sheriffıs department operations center in Orange County, FL, was protected from graffiti with polyurethane coatings.

Photo courtesy of Coatings for Industry, Inc.

J o u r n a l o f A r c h i t e c t u r a l C o a t i n g s / M a r c h / A p r i l 2 0 0 7 25

Texas DOT’s specifications committee;

the green light for its use could come by

the end of the depart m e n t ’s fiscal year,

on Aug. 31.

The pending specification is a perf o r-

mance-based provision, which means

o t h e r, competing products could also

q u a l i f y, as long as they meet the perf o r-

mance bar set by the specification—per-

manent (non-sacrificial) durability and

w a t e r-cleanup capability. For the purpos-

es of the specification, “permanent” is

defined as continued effectiveness for at

least 10 graff i t i - removal events, Schwerd t

s a y s .

“ We’d be delighted if other manufac-

t u rers off e red products that met these

re q u i rements,” he says, adding that speci-

fying a certain product could hinder a

competing product from getting consid-

eration—and contribute to higher costs.

The new specification also will not

mandate acro s s - t h e - b o a rd, statewide use

of the Type 3 antigraffiti tre a t m e n t ,

S c h w e rt adds. The Texas DOT administra-

tion grants considerable latitude to its

various district and area offices in choos-

ing the technology used; the new specifi-

cation simply adds another option.

C h e m i c a l l y, Si-Coat 530 is described as

a flexible silicone elastomer, a form u l a-

tion derived from the silicon family of

materials characterized by unusually low

levels of surface tension. In layman’s

t e rms, this means the surface is simply

too slippery to facilitate adhesion when

another type of material is applied on top

of the silicone.

A consequence of this trait of low sur-

face tension, not surprisingly, is the

inability to successfully apply other types

of coatings or finishes over the antigraff i-

ti silicone treatment. Removal of the

a n t i g r a ffiti coating would be re q u i red if

another type of paint or coating were

applied. Recoating over the silicone anti-

g r a ffiti treatment with the same type of

c h e m i s t ry, however, is not a pro b l e m .

Faisal Huda, general manager of CSL

Silicones, says the distinguishing charac-

teristic of his company’s technology is

the 100% silicone composition of the for-

mulation, with the exception of the carr i-

er solvent.

In addition to the base resin, Huda says

the pro p r i e t a ry Si-Coat 530 form u l a t i o n

includes silicone-derived polymers that

boost adhesion, film formation (cure ) ,

abrasion resistance, and cured-film flexi-

b i l i t y. The elastomeric nature of the

c u red film allows “bridging” over minor

substrate cracks and resistance to defects

or failures due to substrate movement.

26 J o u r n a l o f A r c h i t e c t u r a l C o a t i n g s / M a r c h / A p r i l 2 0 0 7

“ We craft our own polymers,” Faisal

says when asked what sets his company’s

technology apart. “We ’ re one of only a

select few companies that do this. It’s a

competency we developed some time

ago. It gives us control of the form u l a-

t i o n . ”

John Knadler, a sales rep for CSL

Silicones in Texas, Oklahoma, Arkansas,

and Louisiana, says he originally

attempted to sell the product to the

Texas DOT as a maintenance coating for

use on transportation infrastru c t u re .

“When I said it was also good for graff i t i ,

they took notice.” CSL’s core business, in

fact, is anticorrosion coatings, with a par-

ticular emphasis on coatings for power

generation and transmission.

Knadler acknowledges that the pro d-

uct comes with a higher price tag than

some other permanent antigraffiti coat-

ings. But he says potential users should

take into account the pro d u c t ’s re p u t e d

l o n g - t e rm durability and the capability

of graffiti cleanup with just water.

Battle-tested technologiesThe cost issue will no doubt loom large if

CSL Silicones aggressively pursues a sig-

nificant market position alongside major

suppliers of well-established and battle-

tested antigraffiti pro d u c t s — t h e

Degussas, PROSOCOS, Tnemecs, BASFs,

and other makers of coatings and tre a t-

ments for exterior architectural applica-

t i o n s .

Tnemec Co. Inc., known for its range

of high-perf o rmance coatings for the

industrial and architectural market, for-

mally entered the antigraffiti trade in

recent years with a silicone-based coating

o ff e red by the company’s Chempro b e

unit. The product is described as a ro o m -

t e m p e r a t u re - c u re, vulcanized silicone, or

RT V, says Al Morris, Director of

C h e m p robe. The coating product hin-

ders adhesion of graffiti materials, which

a re then removed with the use of a cit-

rus-based paint remover supplied in a

non-VOC (volatile organic compound)

s o l v e n t .

C h e m p robe is primarily a maker of

water repellents, concrete stains, acry l i c

sealers, and concrete curing compounds

and hardeners. “We entered this market

with this product two years ago, in

response to the requests our sales re p s

got for antigraffiti coatings,” Morris says.

C h e m p robe also offers polyure t h a n e -

based antigraffiti coatings for use on

steel, and the company is engaged in

development work on other antigraff i t i

technologies. One goal, Morris says, is

the formulation of permanent (non-sac-

rificial) antigraffiti treatments that will

work effectively over painted surf a c e s

without altering the appearance.

Coatings based on urethane chemistry

remain the pre f e rred technology off e re d

by Coatings for Industry Inc., a

Pennsylvania-based maker of high-per-

f o rmance aerospace and industrial main-

tenance coatings. Kevin Klotz, pre s i d e n t

of the company, says polyurethane coat-

ings provide a strong, durable barr i e r

between substrate and graffiti, facilitating

complete removal of the markings.

The polyurethane technology pro v i d e s

p rotection for 10 to 20 years and has

built a solid re c o rd of proven results in

demanding situations, Klotz says. The

c o m p a n y ’s Urethabond® 111 product is

specified, based on perf o rmance testing

in the field, by transportation agencies in

Pennsylvania, Vi rginia, Maryland, and

New Jersey.

Coatings for Industry ’s extensive port-

folio of antigraffiti applications ranges

f rom New York City subway cars to the

exteriors of major buildings to countless

bridges and other transportation infra-

s t ru c t u re .

Taking the fight to the next levelAs with other segments of the industry,

suppliers of antigraffiti materials are

i n c reasingly prodded to develop new,

m o re environmentally friendly materials,

p a rticularly for use in regions where lim-

its on VOCs and hazardous pollutants

a re being ratcheted downward .

Bayer MaterialScience LLC, a major

supplier of key raw materials for

p o l y u rethane coatings, is working to

develop more waterborne polyure t h a n e

p roducts in response to enviro n m e n t a l

regulations and pre f e re n c e s .

“The waterbornes provide a combina-

tion of resistance pro p e rties and poten-

tially zero VOCs,” says Ed Squiller, tech-

nical manager—maintenance coatings,

for Bayer MaterialScience. The more

p roven solventborne polyurethane tech-

nology offers greater resistance pro p e r-

ties, but the VOC content can be pro b-

lematic in some areas of the country

w h e re air-quality rules are more strin-

gent. Squiller, however, describes the

w a t e r b o rne technology as “still in its

i n f a n c y. ”

P o l y u rethanes are well known for a

p e rf o rmance profile that features high

levels of resistance to chemicals, harsh

cleaners, and UV exposure, along with

film hardness and flexibility that can be

modified to suit specific situations.

Huda, of CSL Silicones, says a 100%

solids, solvent-free version of the compa-

n y ’s silicone-based technology is in

development, with test marketing of the

p roduct anticipated by 2008, at the earli-

est. The new product would be marketed

as an anticorrosion and antigraffiti coat-

ing, he says.

Wa t e r b o rne and non-toxic pro d u c t s

a re off e red by many other companies as

well (see dire c t o ry of suppliers). Still, the

view persists that these products are not

quite on par with the more convention-

al, solventborne materials. Until techno-

logical advances address that re a l i t y,

harsher measures will remain a fact of

life in the war on graff i t i .

JAC

http://www.chemprobe.com/durapell

http://www.graceconstruction.com