AlllOb t102M3

NBSIR 75-789

Graffiti-Resistant Coatings:

Methods of Test and Preliminary

Selection Criteria

M. Godette

M. Post and

P. G. Campbell

Institute for Applied Technology

National Bureau of Standards

Washington, D. C. 20234

November 1975

Final

Prepared for Division of Energy, Building Technology and Standards

Office of Policy Development and Research

tment of Housing and Urban Development

. QQ —ngton, D. C. 20410

100

.U56

75-789

1975

NATUMfAL BUBEAl<

Of STAMSARUS

UBRABY

NBSIR 75-789

MAY 4 1981

GRAFFITI-RESISTANT COATINGS:

METHODS OF TEST AND PRELIMINARY

SELECTION CRITERIA

Qc loo

M. Godette

M. Post and

P. G. Campbell

Institute for Applied Technology

National Bureau of Standards

Washington, D. C. 20234

November 1975

Final

Prepared for Division of Energy, Building Technology and Standards

Office of Policy Development and Research

Department of Housing and Urban Development

Washington, D. C. 20410

U.S. DEPARTMBVT OF COMMERCE, Rogers C.B. Morton. Ucffr^

James A. Baker, III, \lni%f Stentary

Dr. Betty Ancker>Johnson, AatitUmt Saentary for Se/ence and T»ehnoio§y

NATIONAL BUREAU OF STANDARDS, Ernest Ambler, Acting DInetor

TABLE OF CONTENTS

Page

ABSTRACT vl

SI CONVERSION UNITS vll

1. INTRODUCTION 1

1.1 Approach 1 1.2 Objectives 1 1.3 Identification and Evaluation of Graffiti-Resistant Coatings 2 1.4 Description of Marking Materials and Building Substrates 2 1.5 Measurement of Removal Effectiveness 2

2. METHODS OF TEST FOR GRAFFITI-RESISTANT COATINGS 9

2.1 Preliminary Screening g ^ 2.2 Removal Tests of Spray Paints from Coated Brick 10 2.3 Natural Weathering of Graffiti-Resistant Coatings 10 2.4 Removal Tests of Felt-Tip Pen, Crayon, and Lipstick Markings 10 2.5 Resistance to Ultraviolet Radiation 15 2.6 Resistance to Condensing Moisture 15 2.7 Abrasion Resistance 18 2.8 Water Vapor Permeance 18 2.9 Flexibility 23 2.10 Resistance to Graffiti Removers 23

3. SUMMARY AND CONCLUSION 23

4. RECOMMENDED INTERIM CRITERIA FOR GRAFFITI-RESISTANT COATINGS 29

4.1 Ease of Graffiti Removal 29 4.2 Resistance to Discoloration 30 4.3 General Durability 31

5 . REFERENCES 34

iii
LISTING OF TABLES

Table No. Page

1 Effectiveness of Removal of Felt-Tip Pen, Crayon and Lipstick Markings

from Coatings on Tile , 3

2 Spray Paints Used to Determine the "Ease of Removal" of Paint from

Coated Brick 7

3 Dimensions and Physical Properties of Brick 11

4 Average Color Retention of 19 Coatings on Brick After Removal of 18

Spray Paints by 2 Removers 13

5 Extent of Yellowing of Coatings Due to Natural Weathering at the NBS

Site 14

6 Ranking of Weathered Coatings on Brick According to Effectiveness of

Removal of Felt-Tip Pen, Crayon and Lipstick Markings 16

7 The Effect of Condensing Moisture on the Color Retention of Coatings on Brick 21

8 Visual Assessment of Effects of Accelerated Weathering on Coatings on Brick 22

9 Physical Properties of Coatings 26

10 The Effect of Graffiti Removers on Coatings on Brick 27

iv
LISTING OF FIGURES

Figure No. Page

1 Lapping Wheel and Polishing Unit 12

2 Color Change of Graffiti-Resistant Coatings 17

3 Condensed Moisture Test 19

4 Abrasion Test Apparatus 20

5 Water Vapor Permeability , 24

6 Mandrel Elongation Test 25

V
ABSTRACT

The performance of graffiti-resistant coatings was evaluated and criteria were developed to aid in the selection of these materials.

From preliminary test of A7 commercially-available coatings, 19 were selected for more detailed study. The 19 coatings were evaluated for ability to release common markings and

to resist ultraviolet radiation, high humidity, condensing moisture, abrasion and resistance

to graffiti removers. The flexibility and water vapor permeance of the coatings were also

determined. The substrates used were clay brick and a matte tile. Coatings highly resistant

to defacement by spray paint, and highly resistant to felt-tip pen, crayon and lipstick

markings were identified.

Key words: Color retention; ease of removal; graffiti; graffiti-resistant coatings;

performance.

vl
SI CONVERSION UNITS

In view of the present accepted practice In this country for building technology, common

U.S. units of measurement have been used throughout this publication. In recognition of the

position of the United States as a signatory to the General Conference on Weights and

Measures, which gave official status to the metric SI system of units in 1960, appropriate

conversion factors have been provided in the table below. The reader interested in making

further use of the coherent system of SI units is referred to:

NBS SP330, 1972 Edition, "The International System of Units"

E380-72 ASTM Metric Practice Guide (American National Standard Z210.1)

Table of Conversion Factors to Metric (S.I.) Units

Physical To convert to multiply by

Quantity from

Length inch meter 2.5A* X foot m 3.048* J: 10

^

Area inch^

foot

2

""2 m

6.4516*

9.290 X X IQ-^

10"'^

Volume inch^

foof^

3 "3m

1.639 X 2.832 X 10

^

Temperature Fahrenheit Celsius t - ('^F-32)/1.8

c Temperature difference Fahrenheit Kelvin K = ( ^F)/1.8

Pressure inch Hg (60F) newton/m^ 3.377 X

Mass Ibm kg 4.536 X 10-1

Mass/unit area Ibm/ft^ kg/m^ 4.882

Moisture content rate

2 Ibm/ ft week kg/m^s 8.073 X 10-^

Density Ibm/ft-^ kg/m"^ 1.602 X 10^

Thermal conductivity Btu/hr ft^ (F/inch) Wmk1.442 X 10-1

U-value Btu/hr ft^ F W

2, m k

5.678

Thermal resistance F/(Btu/hr ft^) K/(W/m2) 1.761 X 10-1

Heat flow Btu/hr ft^ W/m"^ 3,155

*Exact value; others are rounded to fourth place.

vil

1 . INTRODUCTION

The "graffiti problem," removal of common markings from building materials, haa been

estimated by Gossett [1]* to cost 600 million dollars annually. The problem exists In public, private, commercial and industrial buildings. Substantial savings could be made

by the Department of Housing and Urban Development (HUD) if the exposed surfaces In public housing resisted defacement by graffiti. Therefore, HUD Initiated a program to identify and evaluate coatings which resist defacement by marking devices.

It was learned from observing single and multi-family public housing units in Baltimore,

Washington, Philadelphia, Chicago and Los Angeles that the exposed building materials of

public housing were not easily cleaned of graffiti. Surfaces most frequently used by the

graffiti artist were hallways, stairwells, vestibules, laundry rooms and lower exterior

walls. These surfaces were generally finished with porous materials such as brick,

concrete block and cast concrete. The markings are absorbed by these materials, thereby

making removal difficult. There is, therefore, a need for coating materials which would

resist the absorption of markings into these porous surfaces and be easily cleaned.

Coatings of this kind would not only simplify removal but substantially reduce the cost of

building maintenance.

The study of graffiti-resistant coatings described here Is Part II of a study which

included evaluation of graffiti removers. The evaluation of graffiti removers has already

been reported to the sponsor [2].

1 . 1 Approach

The project was conducted In the following phases:

1. Phase 1 consisted of the identification of materials accessible to defacement

in public housing, and Identification of potential coatings to protect these

materials from defacement. A literature survey of methods used for the removal

of markings from building materials was also Included.

2. Phase II was a laboratory evaluation of the effectiveness of commercially

available graffiti removers.

3. Phase III was an evaluation of the performance and durability of proposed

graffiti resistant coatings.

4. Phase IV was the development of interim criteria for the performance of

graffiti removers and graffiti-resistant coatings.

1.2 Objectives

The objectives of the work described in this report were:

1. To identify commercially available coatings for commonly exposed building

materials such as brick, concrete block, cast concrete and wood that would serve

as release agents for removal of graffiti.

2. To select tests for evaluating the protective, and the functional characteristics of these graffiti-resistant coatings.

3. To evaluate commercially-available graffiti-resistant coatings and recommend

interim performance criteria for their selection.

This report presents the information on graft itl-reslstant coatings of Phases III and

IV Including methods of test. The purpose of the selected tests is to detect changes in

the protective and functional properties of the materials.

Numbers In brackets represent references given in this report.

1
1,1 lilani If (cat l(it) iiiut Rvuliiai Ion at (Jraf f It 1-Haal«tiint CoatlnRi

liiaftlil reHlHtiint coatluga muat provide for tho affective ramoval of common marklngn

In tiddltlon to protecting hulldlnR matarlala. A coating muat narva aa a relciaBa ag^nt to

a variety of markings In order to be effective. Marking materials moat frequent ly used to deface surfaces are spray paint, felt-tip pen, crayon and llpatick.

Potential graffiti-resistant coatings were identified by a review of the literature,

contact with persons in the coatings Industry, public housing engineers, and through

visits to coimnerclal sources. Among the A7 coatings obtained were products claimed to be

suitable for application to steel, brick, tile, wood, concrete, concrete block and stone. Each coating is Identified by a code number in this report so as to avoid the use of

product names.

Table 1 Indicates that more acrylics were available for use as graffiti-resistant

coatings than any other generic type. The generic identification of the various coatings

was determined by infrared analysis. The 47 coatings included 15 acrylics, 7 modified

acrylics, 4 methacrylates, 6 urethanes, 4 modified urethanes, 3 epoxies, 2 silicones, 4 polyesters, 1 poljrvinyl acetate and 1 polyvinyl butyral.

A screening test (Section 2.1) was employed to eliminate from further study those

coatings that showed poor resistance to defacement, and/or lack of film integrity. The

most promising coatings were then quantitatively evaluated for their ability to serve as release agents and to protect building materials.

1.4 Description of Marking Materials and Building Substrates

The marking materials and devices selected for the study included aerosol paints,

crayons, felt-tip markers and lipstick. The selection of marking materials to be used in

the program was based on those general types frequently used by the graffiti artist, and

their availability in local stores. The resin type, color and sample number of each spray

paint are listed in Table 2. In addition to the spray paints listed in Table 2, the

following materials were used:

Felt-Tip Pens - The colors selected were orange, black, red and black and manufactured* by Carter Ink, Skilcraft, Zip Mark and Flair Mfg. Co., respectively.

Crayons - The crayon colors used were orange, pink, gold, dark green, black and

light green and were manufactured by the Crayola Company.

Lipstick - The lipstick colors were pink, gold frost and burnt sugar and were manufactured by Avon, Max Factor, and Elizabeth Arden Company, respectively.

Characteristics of the brick, tested in accordance with ASTM C-67-66 [3], are listed

in Table 3. This brick was used as a substrate, as was matte tile conforming to U.S. Department of Commerce Specification USAS A1371-1967. These materials were chosen for

their similarity to building materials used most frequently in public housing.

1.5 Measurement of Removal Effectiveness

As a basis for establishing limits of performance for graffiti-resistant coatings, it is necessary to be able to evaluate the degree to which the uniform appearance of the sub- strate can be restored following defacement by graffiti. To do this, a Hunter ColorDifference Meter [4] was used to measure the change in appearance. Measurements were made

on each specimen before application of the graffiti and after the cleaning process.

"Clean" implies a generally uniform appearance with no discoloration other than that due

to weathering. Any departure from being clean can be considered unsatisfactory.

*Identif Ication of commercial products is included only to adequately specify the procedure.

Identification does not imply recommendation or endorsement by the National Bureau of

Standards

.

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8
The color change, AE, in NBS units [5] was computed from these measurements and

expressed in terms of color retention, C.R., which was defined as [6]:

C.R. - 100 - AE*

An NBS unit is equivalent to the (AE) as determined in Method 6123 of Federal Test Method Standard lAl [5].

2. METHODS OF TEST FOR GRAFFITI-RESISTANT COATINGS

Measurements of physical properties of coatings are used in assessing their performance

attributes. These laboratory measurements have been used to predict the probable performance

of coatings, since long term performance evaluation of the coatings is difficult and time

consuming. For example, to determine the colorf astness of a coating under in-use conditions,

monitoring over a period of years is required; however, when exposed to Weather-O-Meters

testing, this property of the coating is accelerated and may be characterized within a few

months.

The following tests were chosen to measure those physical properties which are directly

related to the performance of graffiti-resistant coatings. The data obtained is presented

below and the tests are referenced in the interim performance criteria of Section 4.

2.1 Preliminary Screening

The purpose of this test was to evaluate the cleanability of the coatings and to eliminate the poor performers from further study.

The coatings were applied by brush, in duplicate, to the matte tile substrate (Section

1.4), in accordance with the supplier's directions, and cured for 7 days at 23 + 2°C and

50 ± 5% rh. Measurement of film thickness indicated a thickness range from 0.0375 to 0.0825 mm.

The coated tiles were then marked by drawing 6 lines of crayon, 4 lines of felttip

markings and 3 lines of lipstick (brand or manufacture and color of each line are identified

in Section 1.4), and aged 21 days at 23 ± 2°C and 50 ± 5% rh.

For testing, each tile was centered on a lapping wheel (figure 1) and held in place

by me^ns of double-sided adhesive tape. A cellulose sponge was then charged by applying

50 cm of distilled water and rubbed with cake grit soap (conforming to PS-571, Type A) 25 times back and forth across the sponge. The charged sponge was placed in the center of

the tile and the spindle attached to the polishing unit. The lapping wheel and polishing

unit were then operated for one minute as described in "A Test for the Cleanability of

Surface Finishes" [10].

Results of the screening tests are shown in Table 1. It can be seen that markings

applied by felt-tip pens were, in general, more difficult to remove than crayon or lipstick.

Only four coatings permitted the removal of the markings produced by all four pens, whereas

most of the coatings were easily cleaned of crayon and lipstick. As indicated in Table 1,

acrylics were easily cleaned of felt-tip pen markings; however, failures due to peeling,

flaking and film erosion were most common among this group. Film integrity ratings of

"good", "fair", or "poor" are used as indicators of film failures. The coatings retained

for further study were: Nos. 4, 5, 14, 17, 18, 22, 23, 29, 32, 33, 37, 38, 39, 42, 43,

44, 46, 47, and 48.

*The color difference parameter, Rd (the 45°, 0° luminous daylight reflectance), a redgreen) and b (yellow-blue) were measured with a color difference meter. The color change

in NBS units was calculated by the following formula:

Color change (AE) = vj (10>| 'A'd)^ + a2 + b2.

9
2,2 Removal Teats of Spray Paints from Coated Brick

The coatings selected from the preliminary screening tests were next tested for the

protection of bricks, since brick is a common public housing material which is more difficult

to clean than matte tile. The purpose of this test was to determine the ease with which

markings could be removed from coatings applied on porous or absorptive materials.

In this test, 18 spray paints (Table 2) chosen because of their difficulty of removal

from unprotected brick [2] were applied to cured (7 days at 23 ± 2°C and 50 ± 5% rh)

coatings on brick. Two sets of specimens (each comprising 18 paints) were prepared for

each coating. After curing of the paint (7 days at 23 ± 2°C and 50 ± 5% rh) , attempts were made to remove the paint films from the coated brick. Remover 86 (mildly alkaline) was used for one set and remover 98 (highly alkaline) for the other. Application was in

accordance with the supplier's directions, except that the contact time prior to washing

was extended to 30 minutes to obtain maximum removal effectiveness. Then, the paints were

washed from the coated brick with 5 gal/min of high pressure (1600 psi) water to remove

the paint film. After drying, photometric measurements of the appearance were made by a color difference meter [4] and used with the results of measurements made before application

of the paint to determine the color retention.

It is shown (Table 4) that the average color retention value for each coating is

approximately 93. This represents a significant increase in effectiveness when compared

to the average value of 88 obtained in removing graffiti from unpainted brick [2], since

the higher color retention value was obtained for paints which were known to be particularly

difficult to remove [2]. The removal process was shortened and a second application of remover was often unnecessary. The most effective coatings were: Nos, 5, 42, 44, 32, 22,

23, 37 and 14,

2.3 Natural Weathering of Graffiti-Resistant Coatings

Coatings used on exterior surfaces must resist the effects of the outdoor environment.

The purpose of this test was to determine the ability of the coatings to resist discoloration

when exposed to natural weathering.

Duplicate specimens were prepared by applying each coating to the face of brick. The

supplier's directions for spreading rates were used. The coatings were cured for 7 days

at 23 + 2°C and 50 ± 5% rh. The specimens were then exposed at an angle of 45° south at

the NBS Exposure Site for 10 months (May 5, 1974 - March 14, 1975), Measurements of

surface color before and after exposure were used to calculate yellowness index difference

[9] as specified in Method 6031 of Fed. Test Method Std. 141a. The yellowness index is a measure of the distance away from white toward yellow in the color coordinate system. The

yellowness index difference is the difference between the yellowness index after exposure

and the yellowness index before exposure [7].

Results of exposure of the 19 coatings at the NBS Gaithersburg site are shown in

Table 5, The table gives the average yellowness index differences [7 J for duplicate

samples exposed for a period of ten months.

Coating numbers 38, 39, 42, 43, 47, and 48 showed the least tendency to yellow when

exposed to the outdoor environment. Resistance to yellowing is essential for coatings

suitable for application to exterior surfaces, but would not be a consideration for

determining suitability for interior use.

2.4 Removal Tests of Felt-Tip Pen, Crayon, and

Lipstick Markings

Since coatings must retain their functional properties for long periods of time under

exposed conditions, the ease of removal of graffiti from 19 weathered coatings was determined.

10
Table 3. Dimensions and Physical Properties of Brick'

Saturation Coefficient 0.76 Width (mm) 90.,4

Absorption (%) 24-hr cold 7.1 Length (mm) 193.,5

Absorption (Z) 5-hr boil 9.1 Height (mm) 57,.2

Net Solid Area (%) 79.1 Gross Solid Area (mm) 1750,.4

a/ Brick was tested in accordance with ASTM C-67-66 [3], except that results were expressed

In SI units. Each value In the table represents the average of the results for five

specimens

.

11
Figure 1. Lapping Wheel and Polishing Unit Showing Specimen in

Attached and Unattached Positions

12
Table 4. Average Color Retention of 19 Coatings on Brick After Removal

of 18 Spray Paints** by 2 Removera

Average Color Retention*

Coating No, Generic Type Remover No. 86 Remover No. 98

5 Urethane 96 98

42 Fluorinated Polyester Urethane 94 97

44 Acrylic 95 97

32 Acrylic 95 96

22 Dimethyl Silicone 94 95

23 Dimethyl Silicone 95 95

37 Urethane 95 95

14 Polyester 95 95

29 Acrylic 94 94

4 Vinyl-toluene Acrylate 92 94

17 Methacrylate 93 92

33 Methacrylate dnyu yi

38 Acrylic 89 91

39 Acrylic 89 91

43 Acrylic 89 90

18 Methacrylate 90 89

46 Polyester 88 89

47 Acrylic 87 87 48 Acrylic 80 86 Av. 92 Av. 93

^Duplicate panels for each remover C. R. = 100 - AE. **Table 3.

13
7

Table 5. Extent of Yellowing of Coatings Due to Natural Weathering at the NBS Site

Average

Coating No. Generic Type Yellowness Index Dif f erence*

5 Urethane 0.06

14 Polyester Peeled, flaked

18 Methacrylate 0.05

22 Dimethyl silicone 0.04

23 Dimethyl silicone 0.04

29 Acrylic 0.05

17 Methacrylate 0.05

4 Vinyl-toluene acrylate 0.07

32 Acrylic 0.06

33 Methacrylate 0.05

37 Urethane 0.07

38 Acrylic 0.01

39 Acrylic 0.03

42 Fluor inated polyester urethane 0.01

43 Acrylic 0.03

44 Acrylic 0.02

46 Polyester 0.05

47 Acrylic 0.02

48 Acrylic 0.03

*Average of duplicate specimens.

14
Duplicate npeclmens were prepared by applying each coating to the face of bricks in the mnnner recommended by the supplier. Speclmena were cured for 7 days at 23 ± 2°C and 50 ± 5%

rh. The duplicate specimens were exposed at an angle of A5° south for 10 months (May 5, 1974

- March 14, 1975) at the NBS Galthersburg Exposure Site.

3 Samples were removed, rinsed with approximately 50 cm of water and stored at 23 ± 2°C

and 50 ± 5% rh for 48 hours. Then the color of the exposed coating was determined with a color difference meter [5]. The specimens were next marked with parallel lines, two Inches

long, using 4 felt-tip pens, 3 lipsticks and 6 crayons (brand or manufacturer and color of

each line are identified in Section 1.4), The marked samples were then cured an additional

7 days at 23 ± 2°C and 50 ± 5% rh.

The removal process consisted of applying 10 cm of remover No. 86 over the marked area

and scrubbing by ^and with a cellulose sponge for 35 strokes. The samples were then rinsed

with water 100 cm and scrubbed an additional 35 strokes by hand with a sponge charged^with

cake grit soap conforming to PS-571, Type A. The sponge was charged by applying 50 cm of water and rubbing the soap by hand across its surface for a total of 25 strokes. The samples were rinsed with water (500 cm-^) and allowed to stand 24 hours before evaluating. Again, the

color of the marked area was determined by measuring with a color difference meter and the

change in color was computed [5]

.

Table 6 presents a ranking, by color retention (Section 1.5), of the coatings according

to the effectiveness with which felt-tip pen, crayon and lipstick markings were removed.

The six most effective coatings, in descending order, were numbers 42, 48, 38, 5, 43, and 22. These results indicate that all generic types of coatings may retain high resistance to defacement, even in outdoor exposures.

2.5 Resistance to U^^rfl violet Radiation

Coatings for use on the exterior of buildings must resist U.V. radiation from the

sun. The purpose of this test was to determine the effect of U.V. radiation on the appearance

and integrity of the coatings. Duplicate brick specimens were prepared by applying each

coating to the face of the bricks in accordance with recommendations of the coating supplier.

After curing 7 days at 23 ± 2°C and 50 ± 5% rh, the color of the specimens was determined

with a color difference meter prior to exposure in the twin-arc weathering machine. The

apparatus was operated in accordance with Federal Test Method Standard No. 141a, Method

6152, The instrument was operated for 22 hours per day, 5 days a week and, in each 2 hour

cycle, specimens were exposed to 102 minutes of light, then 18 minutes of light with water

spray. The temperature was maintained at 60 - 2°C. After each interval of 100 hours, the

specimens were removed and stored at 23 ± 2°C and 50 ±5% rh for 24 hours. The yellowness

index difference was then calculated as specified in Method 6131 of Federal Test Method

Standard 141a [7]. Specimens were exposed for a total of 300 hours.

The color changes resulting from 100, 200 and 300 hours of exposure in a Weather-0-

Meter are presented in Figure 2. The data indicate that the initial rate of color change

varies widely among the coatings. Generally, based on color changes at 300 hours, the

coatings could be divided into two categories: (1) those showing a color change at 300

hours of less than 3 NBS units, and (2) those having a change greater than 3 NBS units.

2.6 Resistance to Condensing Moisture

Like U.V. radiation, the condensation of water on the surface of organic coatings is

a major cause of deterioration. The purpose of this test was to determine the ability of

coatings to resist change in appearance during prolonged exposures to condensing moisture.

Duplicate brick specimens were coated (Table 1) in accordance with the supplier's

recommendations. After curing (7 days at 23 ± 2°C and 50 ± 5% rh) , the color of the

coating was determined by measuring with a color difference meter [5]. The moisture

condensation test, described in ASTM D2246-64T Tentative Method for Testing Coated Metal

15
TnbJ«' 6. RnnkliiK oE W*nth*re(l CoatlnnH on Brick According to Kf f cctl venens

of Romova] of Kelt-Tip I'en, Crayon and Lipstick Markings

C oating No. Generic Type Color Retention of Substrate*

42 Fluorinated polyester

urethane

96

48 Acrylic 95

38 Acrylic 95

5 Urethane 94

43 Acrylic 94

22 Dimethyl silicone 94

29 Acrylic 93

37 Urethane 93

23 Dimethyl silicone 92

32 Acrylic 92

14 Polyester 92

44 Acrylic 92

39 Acrylic 91

46 Polyester 90

33 Methacrylate 90

4 Vinyl-toluene acrylate 88

47 Acrylic 87

18 Methacrylate 85

17 Methacrylate 80

*Color Retention, C.R. = 100 - AE (duplicate specimens).

16
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.S|>ec LineiiH hL 100 Percent Relative Ihimltllty |8], Hubjectecl apeclmens to condensation trom

heatftd water. Duplicate speclmenH were placed face down on an inclined rack over a pan of

heated water at 44 ± 2°C for 14 days. The angle of the specimens permitted the moisture

condensing on the specimens to run back into the reservoir. The surface color was measured

after exposure and the color retention (see Section 1.5) was calculated as described in

Method 6123 of Federal Test Method Standard 141a [5].

Significant changes occurred in all the coatings within 14 days. The average color

retention values for duplicate specimens of each coating, in Table 7, show the effects of condensing water. Coating numbers 42, 29, 22, 48, 18, 14, 5, 38, 46 and 47, in descending

order, were- the ten most resistant coatings to condensing water.

The effects of condensing water and U.V. radiation (by Weather-O-Meter) on the appearance of coated brick are shown in Table 8. Because of the color changes caused by condensing

water, graffiti-resistant coatings must be selected judiciously where the condensation of

water is likely to occur.

2.7 Abrasion Resistance

Coatings that permit the removal of marking materials must retain their integrity

during abrasion which might occur while in service and in the removal process. The purpose

of this test was to determine the abrasion resistance of the coatings.

The test method was as described in Method 6192 [11] of Federal Test Method Standard

141a, Duplicate specimens were prepared by applying the coating by brush to 100 x 100 mm

solvent cleaned No. 21 gage cold rolled steel according to the manufacturer's recommended

spreading rate for smooth surfaces. The specimens were cured for 7 days at 23 ± 2°C and

50 ± 5% rh. Then a 6.25 mm diameter hole was drilled in the center of each steel square

to permit mounting onto the abrasion tester (figure 4)

.

The initial weight of each square specimen was determined to the nearest milligram

and mounted as directed in Method 6192 [11]. Using CS-17 calibrase wheels with a load of

500 grams on each wheel, the specimen was abraded for 500 cycles, and its weight loss

determined.

The results of the abrasion tests are given in Table 9. It is seen that the urethane

showed the greatest resistance to abrasion, while the acrylics, showed a wide range of

abrasion resistance. Coating number 37 showed the lowest weight loss (1.5 mg), and coating

number 22 showed the highest weight loss (39.6 mg) . Resistance to abrasion is an essential

property of coatings to be used in areas where direct contact with moving objects is

likely, e.g. hallways, stairwells, doors and handrails.

2.8 Water Vapor Permeance

The application of coatings to building materials frequently causes problems by

changing the pattern of moisture migration. The purpose of this test was to determine the

suitability of graffiti-resistant coatings to aid in the control of water vapor. For example, to prevent the penetration of water vapor into walls and ceilings of bathrooms,

kitchens and laundry rooms, these areas are frequently painted with highly impermeable

coatings. Conversely, exterior areas, such as concrete walls, and wood sidings are frequently

painted with permeable coatings to permit the transfer of water vapor within the walls to the exterior environment.

The basic test method used is described in ASTM E96 [12]. Duplicate specimens were

prepared by application of the coatings to the highly permeable portion of penetration

chart forms* at a wet film thickness of 0.125 mm. The specimens were then cured for 7 days at 23 ± 2°C and 50 ± 5% rh.

*Charts (Form HK) may be obtained from the Leneta Company, P.O. Box 576, Ho-Ho-Kus,

New Jersey.

18
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Figure 4. Abrasion test apparatus with abraser wheels being

refaced on an abrasive disc.

20
Table /. The Effect of Condensing Moisture on the Color

Retention of Coatings on Brick

Generic Type Average Color R«

42 Fluorlnated polyester urethane 88

29 Acrylic- 87

i: Dimethyl silicone 85

Acrylic 85

18 Methacrylate 84

lA Polyester 84

5 Urethane 84

38 Acrylic 84

46 Polyester 83

47 Acrylic 82

39 Acrylic 82

23 Dimethyl silicone 81

17 Methacrylate 81

4 Vinyl-toluene acrylate 8i

44 Acrylic 81

32 Acrylic 80

33 Methacrylate 80

37 Urethane 80

43 Acrylic 76

*Color Retention, C.R. - 100 - AE (duplicate specimens)

21
Table 8. Vlaual AsseBsment of Effects of Accelerated

Weathering on Coatings on Brick

Coating No. Condensing Moisture (lA days) Weather-O-Meter , 60''C A4 ± 2°C U.V., Water Spray (300 hours)

•'l Slight darkening No visible effect

'> No visible effect No visible effect

14 Erosion of coating Erosion

17 No visible effect Slight darkening

18 No visible effect Erosion

22 Erosion and whiting Erosion

23 No visible effect Erosion

29 Discoloration Flaking

32 No visible effect Erosion

33 Erosion of coating Erosion

37 No visible effect No visible effect

38 No visible effect Erosion

39 No visible effect Whitening and yellowing

42 No visible effect No visible effect

43 No visible effect No visible effect

No visible effect No visible effect

46 No visible effect No visible effect

47 No visible effect Slight discoloration

48 Slight darkening Slight yellowing

22
A disc (100 mm In diameter) cut from the chart with the cured film waa sealed over

the mouth of a permeability cup (figure 5) containing a desiccant and was placed In an atmosphere of 23 ± I'C and 50 ± 5% rh. The assembly was weighed once every 24 hours, and

the results for the period in which the gain In weight was linear with time were used to calculate the rate, in perms, of water vapor movement through the membrane.

The permeability of the coatings ranged from a low of 0.8 perms for number 5, to a high of 10.4 perms for number 42 (Table 9).

2.9 Flexibility

Organic coatings are formulated with varying degrees of ability to be deformed without

cracking, checking or crazing. The purpose of the flexibility test was to determine the

ability of coatings to resist deformation without damage.

Duplicate specimens of the coatings were applied to metal panels (Fed. Spec. QQ-S698) at a wet film thickness of 0.125 mm by doctor blade** (a precision instrument designed

for the application of uniform films of organic coatings) . The coatings were cured for 7 days at 23 ± 2''C and 50 ± 5% relative humidity. The samples were removed and tested as outlined in Method 6221 of Fed. Test Method Std. 141 [9]. The specimens were subjected to both the 3,13 mm and the 6.250 mm mandrel tests (figure 6).

The results in Table 9 showed that many of the coatings were able to pass the flexibility test [9] on both mandrels. However, those that failed the 3.13 mm bend test, generally

failed the 6.25 mm test also and would be considered poor.

2.10 Resistance to Graffiti Removers

If coatings are to provide lasting protection for building materials, they must

resist removers used for cleaning markings from those materials. The purpose of this test was to evaluate the resistance of coatings to removers with which they are likely to come

into contact during normal use.

Duplicate specimens were prepared by brush application of each coating to 100 x 1^0 x 6.25 mm matte tile, and allowed to cure for 7 days at 23 ± 2°C and 50 ± 5% rh. One cm of

the nineteen commercially available removers was placed in a 2.54 cm area on each coating

and covered immediately with a watchglass. After one hour, the watchglass was removed,

the solution washed away and the panel examined for wrinkling, blistering, lifting and

discoloration of the coating.

The results are given in Table 10. Coating numbers 29, 32, 33, 38, 39 and 43 showed

poor resistance to removers while coating numbers 5, 18, 22, 23, 37, 42, 44, 47 and 48 were highly resistant to removers. From this data, it was possible to identify compatible

coating-remover combinations and thereby minimize the probability of damage to the coating. For example. Table 10 shows that remover numbers 8, 10, 17, 35, 59, 61, 62 and 78 would be

appropriate for removal of markings from coating number 5; damage would be likely to occur

if remover numbers 13, and 15 were used.

3. SUMMARY AND CONCLUSIONS

The results reported in Section 2 indicate that organic coatings can provide for the

effective removal of markings. Nineteen coatings were evaluated and ranked according to the ease of removal of felt-tip pen, crayon, lipstick and spray paint markings. The

performance of the coatings as protective membranes for building materials was also determined.

Results of the laboratory tests reported in Section 2 show that organic coatings provide a wide variety of functions and perform at various levels of efficiency. For this reason.

It is necessary to select coatings according to the function and level of performance

required.

*Doctor blades may be obtained from the Gardner Laboratory, Inc., 5521 Landy Lane,

Bethesda, Maryland.

23
Figure 5. Water permeability test cup assembly.

24
Figure 6. Series of mandrels showing test specimen

being bent over 2.125mm mandrel.

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27
Table 1 shows that more acrylics were available for use as graffiti-resistant coatings

than any other generic type. The nineteen coatings selected for further evaluation were

comprised of 8 acrylics, 3 methacrylates, 2 silicones, 1 modified acrylic, 2 urethanes, 1 modified urethane and 2 polyesters.

Studies of the effectiveness of removal indicated that spray paint and felt-tip pen

markings, two of the most difficult to remove markings, can be effectively removed from

coated brick. Eight coatings had a color retention value of 95 or more after the removal

of spray paint; 12 coatings had a color retention value of 92 or above after the removal

of felt-tip pen, crayon, and lipstick markings (Table 6)

.

Exposure of the coatings to conditions encountered in the outdoor environment showed

that care must be exercised in their selection to ensure that they do not discolor, abrade

or erode from the substrate. Eleven coatings had a color retention value of 95 or more

(figure 2) after exposure for 300 hours in the twin-arc Weather-O-Meter ; 11 coatings had a color retention value of 82 or more after exposure to continuous condensation for two weeks (14 days)

.

The abrasion resistance of the coatings (ability to resist mechanical wear) was also

determined. Thirteen samples showed an average weight loss (duplicate specimens) of not more than 30 milligrams when abraded as outlined in Section 2.7.

The water vapor permeance results (Table 9) showed that the coatings are permeable

and permit the transfer of water vapor. Only one coating, number 5, was highly resistant

to the transfer of water vapor (e.g. permeance less than 0.9 perms).

Data in Table 9 showed that graffiti-resistant coatings were able to pass the flexibility test on both mandrels. Thirteen coatings passed the 3.13 mm bend test. These coatings were considered to be flexible and suitable for application to substrates where expansion

and contraction would be likely to occur.

The resistance of coatings to graffiti removers is shown by data in Table 10. Coating

numbers 29, 32, 33, 38 and 39 showed poor resistance to removers while coating numbers 5,

18, 22, 23, 37, 42, 44, 47, and 48 were highly resistant to removers.

The selection of graffiti-resistant coatings requires Identifying specific functions

and specifying levels of performance required. The tables given in Section 2 identify

properties necessary for the evaluation of durability and show levels of performance for

each.

From the experiments on the ease of removal of markings, and the performance of 19 graffiti-resistant coatings, the following conclusions were reached:

1. A quantitative rating of the resistance of a coating to defacement can be

based on measurements with a color difference meter.

2. No one coating performed all functions well.

3. Criteria based upon the evaluation in this report will aid in the selection

of organic coatings that resist defacement by marking devices.

4. Coatings highly resistant to defacement by crayon, felt-tip pen, and lipstick

were: Nos. 42, 48, 38, 5, 43, an4 22.

5. Coatings most resistant to spray paint were: Nos. 5, 42, 44, 32, 22, 23,

and 37.

6. Generally, many of the coatings exhibited failures that frequently characterize

unpigmented coatings, e.g., erosion, film cracking, discoloration and checking.

7. The coatings demonstrated the capability to provide many functional properties,

e.g., high permeability, low permeability, high resistance to U.V. radiation and

resistance to condensing water.

28
8. Most of the coatings were permeable and therefore, permitted the transfer

of water vapor.

Taking Into account the factors mentioned above, and based on the data reported in

Section 2, tentative selection criteria for graffiti-resistant coatings, to be used for

the protection of substrates from defacement, have been established. These tentative

criteria are presented in Section 4.

A. RECOMMENDED INTERIM CRITERIA FOR GRAFFITI-RESISTANT COATINGS

Although there is no substitute for long-term in-service performance evaluation, the

laboratory test results presented In Section 2 provide the basis for the following interim

criteria for graffiti-resistant coatings. The criteria are preliminary and may need to be

up-dated as additional information becomes available.

4.1 Ease of Graffiti Removal

Requirement

Graffiti-resistant coatings should make it easy to remove common marking materials from

surfaces of architectural materials to which they are applied. The ease and effectiveness

of removal should reflect the minimum performance levels satisfying the user's needs.

Criterion 1 - Ease of Removal (Spray Paint)

When tested as outlined below, the color retention shall not be less than 95 for the

removal of spray paint

.

Test

The eighteen spray paints (Table 2) are applied to cured (7 days at 23 ± 2°C and 50 ± 5% rh) coatings on brick. Two sets (each comprising 18 paints) are formed for each coating.

After curing of the paints (7 days at 23 ± 2°C and 50 ± 5% rh) , ease of removal of the

paint from the coated brick is evaluated. Remover 86 (mildly alkaline) is used for one

set and remover 98 (highly alkaline) for the other. Application is in accordance with

the manufacturer's directions, except that the contact time prior to washing is extended

to 30 minutes to obtain maximum removal effectiveness. After 30 minutes, the paint is

washed from the coated brick with 5 gal/min of high pressure (1600-1900 psi) water to remove the paint film. After drying, photometric measurements of the appearance of each

brick are made by a color difference meter [4] and used with the results of measurements

made before application of the paint to determine the color retention.

Criteria 2 - Ease of Removal (Felt-Tip Pen, Lipstick and Crayon Markings)

When tested as outlined below, the color retention shall not be less than 92 for the

removal of felt-tip pen, lipstick and crayon markings.

Test

Two bricks (Table 3) are prepared for each coating by applying the coating to the

faces of bricks in the manner recommended by the supplier. The coated specimens are cured

for 7 days at 23 ± 2°C and 50 ± 5% rh. The specimens are exposed at an angle of 45° south

for 10 months (May 5 - March 14) at the NBS Gaithersburg Exposure Site.

3 Following removal from the site, the samples are rinsed with approximately 50 cm of

water and stored at 23 ± 2°C and 50 ± 5% rh for 48 hours. Then the colors of the coatings

are determined with a color difference meter [5]. Next, the specimens are marked with

parallel lines, two Inches long, using 4 felt-tip pens, 3 lipsticks and 6 crayons (brand

or manufacturer and colors to be used are identified In Section 1.4). The marked samples

are then cured for an additional 7 days at 23 ± 2°C and 50 ± 57, rh.

3 The removal process consists of applying 10 cm of remover No. 86 (mildly alkaline) over the marked area and scrubbing by hand with a cellulose sponge for 35 strokes. The

29
samples are then rinsed with water (100 cm ) and scrubbed an additional 35 strokes by

hand with a sponge charged with cake grit soap conforming to PS-571, Type A. The sponge

is charged by applying 50 cm^ of water and rubbing the soap by hand adross its surface for

a total of 25 strokes. The samples are rinsed with water (500 cm-^) and allowed to stand

24 hours before evaluating. Again, the color of the marked area is determined by measuring

with a color difference meter and the color retention computed [5].

Commentary

Generally, porous materials such as brick, concrete block and cast concrete absorb common marking materials, thereby making removal difficult. These criteria were selected

so as to recognize graffiti coatings which minimize the difficulties in removing spray

paint, felt-tip pen, lipstick and other crayon markings. The limits specified in these

criteria reflect results obtained in removing felt-tip pen, spray paint, crayon and lipstick

markings from coated bricks by a common removal method. The criteria reflect our present

best judgment. Although they are based on results for the coatings on brick, we believe

they will also be a good guide to coating performance on other architectural materials.

Eight of the 19 coatings subjected to the tests met the requirement for the removal of

spray paint; 12 of the coatings met the requirement for the removal of felt-tip pen, crayon

and lipstick markings. The coatings meeting both requirements were: Nos. 5, 42, 44, 32, 22,

23, 37 and 14.

4.2 Resistance to Discoloration

Requirement

Graffiti-resistant coatings should maintain their original appearance even after prolonged exposure to the outdoor environment.

Criterion 1 - Effect of U.V. Radiation

Vfhen subjected to U.V. radiation as outlined below, the coating shall have a color

retention value of not less than 97 (minimum performance level) after 300 hours of exposure.

Test

Duplicate specimens are prepared for each coating by applying it to the face of two bricks (Table 3) in accordance with recommendations of the coating supplier. Specimens are cured for 7 days at 23 + 2"'C and 50 ± 5% rh. The colors of the specimens are determined with

a color difference meter prior to exposure in the twin-arc weathering machine. The apparatus

is operated in accordance with Federal Test Method Standard No. 141a, Method 6152. The

instrument is operated for 22 hours per day, 5 days a week and, in each 2 hour cycle,

specimens are exposed to 102 minutes of light, then 18 minutes of light with water spray. The temperature is maintained at 60 ± I'C. After each interval of 100 hours, the specimens

are removed and stored at 23 ± 2''C and 50 ± 5% rh for 24 hours. The yellowness index difference is calculated as specified in Method 6131 of Federal Test Method Standard 141a [7].

Specimens are exposed for a total of 300 hours.

Criterion 2 - Effect of Condensing Moisture

When subjected to condensing moisture as outlined below, the coating shall have a color

retention value of 82 (minimum performance level) after 14 days exposure.

Test

For each coating, the faces of duplicate brick specimens are coated (Table 1) in

accordance with the supplier's recommendations. After curing (7 days at 23 ± 2*'C and 50 ± 5% rh) , the colors of the coatings are determined with a color difference meter [5]. The

moisture condensation test, described in ASTM D2247-64T Tentative Method for Testing Coated

Metal Specimens at 100 Percent Relative Humidity [8], subjects specimens to condensation

from heated water. Duplicate specimens are placed face down on an inclined rack over the

pan of heated water at 44 ± 2°C for 14 days. The angle of the specimens permits the moisture

condensing on them to run back into the reservoir. The surface color of each specimen is

measured after exposure and the color retention (see Section 1.5) is calculated.

30
Commentary

These criteria were selected to ensure retention of the original appearance accepted

by users of the coatings. Coatings for use on exterior surfaces should meet both the U.V. radiation and the condensing moisture criteria. However, compliance with these criteria

is not normally necessary for coatings for interior use, since the exposure conditions

will not normally be so severe. The condensing moisture criterion should be applied when

interior coatings are selected for application In areas such as bathrooms, kitchens and

laundry rooms.

4.3 General Durability

Requirement

Graffiti-resistant coatings should have long-service life even under exposure to abrasion, water vapor, deformation of the substrate and graffiti removers.

Criterion 1 - Abrasion Resistance

When tested as outlined below, the average weight loss of duplicate specimens shall

not exceed 30 milligrams.

Test

Duplicate specimens are prepared by applying the coating by brush to 100 x 100 mm

solvent cleaned No. 21 gage cold rolled steel according to the manufacturer's recommended

spreading rate for smooth surfaces. The specimens are cured for 7 days at 23 ± 2°C and 50 ± 5% rh. Then a 6.25 mm diameter hole is drilled in the center of each steel square to permit mounting in the abrasion tester.

The initial weight of each square specimen is determined to the nearest milligram and

mounted as directed in Method 6192 [11]. Using CS-17 calibrase wheels with a load of 500

grams on each wheel, the specimen is abraded for 500 cycles, and its weight loss determined.

Commentary

Interior coatings usually experience their most severe abrasion from occupant traffic

and routine maintenance (cleaning) . Exterior coatings are usually abraded by the forces

of wind-driven rain, sand and other particulate matter. In this criterion, no distinction

is made between the requirements for interior and exterior coatings. However, it should

be noted that in areas removed from occupant traffic (interior wall levels above 2 meters

from the floor) a lower limit may prove satisfactory. This criterion represents our present best judgment based on the results of the test program reported herein.

The expression of abrasion resistance as milligrams of weight loss per number of cycles establishes a meaningful comparison by which coatings can be rated. Thirteen of

the 19 samples tested met the criterion.

Criterion 2 - Water Vapor Permeance

Where water vapor transmission is to be restricted, coatings shall have a water vapor

permeance not greater than 0.9 perms when tested as outlined below.

Test

Duplicate specimens are prepared by application of the coatings to the highly permeable

portion of penetration chart forms* at a wet film thickness of 0.125 mm. The specimens are

cured for 7 days at 23 ± 2°C and 50 ± 5% rh.

A disc (100 mm in diameter) cut from the chart with the cured film is sealed over the

mouth of a permeability cup (figure 5) containing 30 gms of calcium chloride and placed in

*Charts (Form HK) may be obtained from the Leneta Co., P.O. Box 576, Ho-Ho-Kus, New Jersey.

31
an atmosphere of 23 ± 2°C and 50 ± 5% rh. The assembly is weighed once every 24 hours, and

the results for the period in which the gain in weight is linear with time is used to calculate the rate, in perms, of water vapor movement through the membrane.

Criterion 3 - Water Vapor Permeance

Where water vapor transmission is desired, the coating shall have a water vapor permeance

greater than 1.5 perms.

Tes t

Duplicate specimens are prepared by application of the coatings to the highly permeable

portion of penetration chart forms at a wet film thickness of 0.125 mm. The specimens are cured for 7 days at 23 ± 2°C and 50 ± 5% rh.

A disc (100 mm in diameter) cut from the chart with the cured film is sealed over the

mouth of a permeability cup (figure 5) containing 30 gms of calcium chloride and placed in an atmosphere of 23 ± 2°C and 50 ± 5% rh. The assembly is weighed once every 24 hours, and

the results for the period in which the gain in weight is linear with time is used to calculate the rate, in perms, of water vapor movement through the membrane.

Commentary

The sealing of moisture-laden masonry walls by coatings may cause cracking and peeling

of the coating or cracking, spalling and disruption of the wall. The above criteria provide

guidance in the selection of coatings suitable for application to areas where either the

transfer of water vapor or its exclusion is desired; however, an analysis of the water vapor

movement in the structure may be necessary to determine the type of coating required.

A high water vapor transmission is usually required on exterior surfaces while a low

transmission may be required on some interior surfaces. -Only one of the 19 coatings tested met the requirement for restricting the flow of water vapor, while 18 met the requirement

for permitting it.

Criterion 4 - Flexibility

Coatings applied to sheet metal or other easily deformed material shall pass the 3.125 mm mandrel test [8].

Test

Duplicate specimens of the coatings are applied to metal panels (Fed. Spec. QQ-S698) at a wet film thickness of 0.125 mm by doctor blade** (a precision instrument designed

for the application of uniform films of organic coatings) . The coatings are cured for 7 days at 23 ± 2°C and 50 ± 5% relative humidity. The samples are removed and tested

as outlined in Method 6221 of Fed. Test Method 141 [9]. The specimens are subjected to both the 3.13 mm and the 6,250 mm mandrel tests (figure 6).

Commentary

This criterion was selected to ensure that the selected coatings are suitable for

application to building materials subjected to dimensional changes or deformation. Generally, building materials are subjected to dimensional changes when exposed to variations

in environmental conditions. Field experience with coatings which met the above criterion

has shown that they retain an acceptable level of flexibility.

Thirteen of the 19 coatings evaluated met the criterion. This requirement may be

waived for coatings to be used on substrates characterized by little or no deformation.

Criterion 5 - Resistance to Graffiti Removers

When tested as outlined below, the coatings shall not wrinkle, blister or discolor.

**Doctor blades may be obtained from the Gardner Laboratory, Inc., 5521 Landy Lane,

Bethesda, Maryland.

32
Test

Duplicate specimens are prepared by brush application of each coating to 100 x 100 x 6.25 mm matte tile, and allowed to cure for 7 days at 23 ± 2°C and 50 ± 5% rh. One cm^ of the following household and/or industrial products (Big Wally, Knapp All Kleen, Janitor in

a Drum and Novo Clean)*** is placed in a 2.54 cm area on each coating and covered immediately

with a watchglass. After one hour, the watchglass is removed, the solution washed away and

the panel examined for wrinkling, blistering, lifting and discoloration of the coating.

Commentary

Generally, a graffiti remover that attacks most common marking materials is also likely

to affect the surfaces of organic coatings. Coatings that resist the action of graffiti

removers are likely to have longer useful service life and reduced maintenance costs. This

criterion is intended to identify coatings which are able to resist common removers. Eleven

of the 19 coatings evaluated met the criterion.

***Identif Ication of commercial products is included only to adequately specify the test conditions. Identification does not imply recommendation or endorsement by the National

Bureau of Standards.

33
5. REFERENCES

1. Gossett, Ken, "Graffiti: The National Problem," Professional Sanitation Management,

P. 20, Environment Management Association^ Clearwater, Florida 33515, September,

1973.

2. Godette, M. , Post, M., Campbell, P.G., "Graffiti Removers: Methods of Test and Pre- liminary Selection Criteria," NBS Report, in press.

3. "Standard Methods of Sampling and Testing Brick," ASTM Book of Standards, Pt. 12,

1969 (American Society for Testing and Materials, Philadelphia, Pa. 19103).

4. Hunter, R.S., "Photoelectric Tristimulus Colorimetry with Three Filters," NBS Circular

429 (1942).

5. "Color" Difference of Opaque Materials - Instrumental Measurement," Method 6123,

Federal Test Method Standard 141a. Obtained from Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402.

6. Moore, D.G. and Porter, A., "Effect of Exposure Site on Weather Resistance of Porcelain

Enamels Exposed for Three Years," National Bureau of Standards (U.S.) Monograph 44,

April 1962.

7. "Yellowness Index," Method 6131, Federal Test Method Standard 141a. May be obtained

from Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402.

8. "Standard Method for Testing Coated Metal Specimens at 100 Percent Relative Humidity,"

D2247, Appendix 1, ASTM Book of Standards, Pt. 21, 1972 (American Society for Testing

and Materials, Philadelphia, Pennsylvania 19103).

9. "Flexibility," Method 6221, Federal Test Method Standard 141a. May be obtained from

Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402.

10. "A Test for the Cleanabillty of Surface Finishes," Standards Committee, Porcelain

Enamel Institute, Inc., 1971.

11. "Abrasion Resistance (Taber Abraser)," Method 6192, Federal Test Method Standard

141a. May be obtained from Superintendent of Documents, U.S. Government Printing

Office, Washington, D.C. 20402.

12. "Standard Methods of Test for Water Vapor Transmission of Materials in Sheet Form,"

E-96, ASTM Book of Standards, Pt . 14, 1972.

13. "Paint, Varnish, Lacquer, and Related Materials; Methods of Inspection, Sampling, and

Testing," Fed. Test Method Std. 141a, September, 1963. Copies may be obtained from

Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402.

34
NBS-1 14A IR E V. 7.7di

U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

CLJ C C T an c fc 1

1. imUI.K ATION OH Ki:i'OKT NO. NBSIR 75-7892. t lov 't Acci.- s s ion No.

3. Kci- ipii-nt 's Ai L i-ssKin

4. Tl 11. 1-: AND SUin iTl.l-.

Graffiti-Resistant

Selection Criteria

Coatings: Methods of Test and Preliminary

5. Piibl ii ai ion IXin- November 1975

6. Pi rforming Org.in i/a( uin ( o.l<

7. AUTHORlS)

M. Godette, M. Post and P. G. Campbell

8. Pirforming Organ. Report No. NBSIR 75-789

9. PERFORMING ORGANIZATION NAMf- AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Projcct/Task/Work Unii No. 4615442

11. Coniract/Grant No.

12. Sponsoring Organization Name and ( ompletc Address (Street, City, State, ZIP)

Office of Policy Development and Research

Department of Housing and Urban Development

Washington, D.C. 20410

13. Type of Report S: Period

C overedFinal

14. Sponsoring Agency (Ode

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 2 00- word or less factual summary almost sif^ilr .1 : l. irmntion. If document includes a signilicant

bibliography or literature survey, mention it here.) The performance of graffiti-resistant coatings vi/as evaluated and performance tests and

criteria were developed to aid the selection of these materials.

From preliminary test of 48 commercially-available coatings, 19 were selected for more detailed tests. The 19 coatings were evaluated for ability to release common markings

and to resist ultraviolet radiation, high humidity, condensing moisture, abrasion and

graffiti removers. The flexibility and water vapor permeance of the coatings were

also determined. The substrates used were clay brick and a matte tile. Seven of the

coatings were highly resistant to defacement by spray paint, and five were highly

resistant to felt-tip pen, crayon and lipstick.

17. KEY WORDS (six to twelve entries; alphabetical order; capitalize only the first letter of the first key word unless a proper name; separated by semicolons

)

Color retention; ease of removal; graffiti; graffiti-resistant coatings; performance

18. AVAILABILITY 17'/ Unlimited

For Official Distribution. Do Not Release to NTIS

' ' Order From Sup. of Doc, U.S. Government Printing Office Washington. D.C. 20402. SD Cat. No. C13

1 1 Order From National Technical Information Service (NTIS)

Springfield, Virginia 22151

19. SECURITY CLASS

(THIS REPORT)

UNCL ASSIFIED

21. NO. OF PAGES

41

20. SECURITY CLASS

(THIS PAGE)

UNCLASSIFIED

22. Price

USCOMM.DC 29042-P74


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