NATIONAL BUREAU OF STANDARDS REPORT

9462

PROGRESS REPORT

1964 EXPOSURE TEST OP PORCELAIN ENAMELS ON ALUMINUM

One-Year Report

by

Margaret A. Rushmer

November 30, 1966

Porcelain Enamel Institute Research Associateship

National Bureau of Standards

Washington, D. C.

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
THE NATIONAL BUREAU OF STANDARDS

The National Bureau of Standards is a principal focal point in the Federal Government for assur- ing maximum application of the physical and engineering sciences to the advancement of technology

in industry and commerce. Its responsibilities include development and maintenance of the national

standards of measurement, and the provisions of means for making measurements consistent with

those standards; determination of physical constants and properties of materials; development of methods for testing materials, mechanisms, and structures, and making such tests as may he necessary, particularly for government agencies; cooperation in the establishment of standard practices

for incorporation in codes and specifications; advisory service to government agencies on scientific and technical problems; invention and development of devices to serve special needs of the Govern- ment; assistance to industry, business, and consumers in the development and acceptance of commercial standards and simplified trade practice recommendations; administration of programs in cooperation with United States business groups and standards organizations for the development

of international standards of practice; and maintenance of a clearinghouse for the collection and

dissemination of scientific, technical, and engineering information. The scope of the Bureau’s

activities is suggested in the following listing of its three Institutes and their organizational units. Institute for Basic Standards. Applied Mathematics. Electricity. Metrology. Mechanics. Heat. Atomic Physics. Physical Chemistry. Laboratory Astrophysics.* Radiation Physics. Radio Standards

Laboratory:* Radio Standards Physics; Radio Standards Engineering. Office of Standard Reference

Data. Institute for Materials Research. Analytical Chemistry, Polymers. Metallurgy. Inorganic Materials. Reactor Radiations. Cryogenics.* Materials Evaluation Laboratory. Office of Standard Refer- ence Materials. Institute for Applied Technology. Building Research. Information Technology. Performance

Test Development. Electronic Instrumentation. Textile and Apparel Technology Center. Technical

Analysis. Office of Weights and Measures. Office of Engineering Standards. Office of Invention and

Innovation. Office of Technical Resources. Clearinghouse for Federal Scientific and Technical

Information.**

•Located at Boulder, Colorado, 80301. ••Located at 5285 Port Royal Road, Springfield, Virginia, 22171.
NATIONAL BUREAU OF STANDARDS REPORT

MBS PROJECT

421.04-12-4212270

MBS REPORT

9462

PROGRESS REPORT

1964 EXPOSURE TEST OF PORCELAIN ENAMELS ON ALUMINUM

One-Year R.eport

by

Margaret A. Rushmer

November 30, 1966

Porcelain Enamel Institute Research Associateship

National Bureau of Standards

Washington, D. C.

IMPORTANT NOTICE NATIONAL BUREAU OF STAND

for use within the Government. Beft and review. For this reason, the pul whole or in part, is not authorized Bureau of Standards, Washington, D

the Report has been specifically pref

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST) on October 9, 2015

^counting documents intended

ected to additional evaluation ng of this Report, either in

ice of the Director, National

* Government agency for which

! tor its own use. <NBS>

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

PROGRESS REPORT

EXPOSURE TEST OF PORCELAIN ENAMELS ON ALUMINUM

One Year Report

PORCELAIN ENAMEL INSTITUTE RESEARCH ASSOC I ATE'SHIP

NATIONAL BUREAU OF STANDARDS

WASHINGTON, D. C.

INTRODUCTION

The application of porcelain enamels to aluminum is a relatively recent development in the field of porcelain enameling. A few of the early porcelain enamels on aluminum included

!_/ in an exposure test initiated in 195 £ indicated that accelerated tests used with confidence for porcelain enamels on steel

were not reliable indicaiors of the weatherabi li ty of the new,

lower firing porcelain enamels on aluminum. With this knowledge the Aluminum Council of the Porcelain Enamel Institute

agreed to sponsor, with the National Bureau of Standards, an

exposure test consisting solely of porcelain enamels on aluminum.

The new test was to incorporate enamels employing the nine basic

color oxides used in porcelain enamels on aluminum. This test

was also designed to evaluate the effect of varying both the

initial gloss and thickness.

The enamels in this test have been exposed for one year

at Kure Beach, North Carolina; New York, New York: Washington,

D. C. ; Los Angeles, California; and Montreal, Canada. This

report is a summary of the findings of the one-year inspection

and is the second in a series of reports to the sponsors of this
program. the first being a summary of the six-months' inspection

The first published report is tentatively planned after the

three-year inspection.

MATERIALS AND PROCEDURES

1. Enamels

Sixteen enamel systems were included in this test. These

enamel systems are represented by nine colors, three gloss

ranges and both one- and two -coat enamels as indicated in Table

1 . The initial H 5° specular gloss values and the thicknesses

of the enamels as well as their acid solubilities and acid spot

test ratings are also reported in Table 1.

The enamels in this test have been coded for easy identification. Each enamel system can be identified by the first

two code letters, while different fabricators for each enamel

system are indicated by the third code letter. The differences

between the enamel systems are readily apparent (see Table 1)

for all systems except AA and AZ . These systems were planned

to be two-coat enamels having significantly different thicknesses

However, this difference did not materialize during manufacture

of the specimens.

If small variations in milling and firing of the enamels

by the different fabricators are taken into account there are,

in effect, 51 different enamels included in this test.
2. Test Specimens

Each enamel was applied to a 3 X 5 foot sheet of 0.0^4

inch C Oil aluminum alloy. After the enamel was fired the sheet

was cut, with a band saw, into seventy-eight 4-7/lG inch^ and

nine 4x6 inch exposure specimens. This was done to produce

more uniform specimens than could be obtained by hand spraying

and firing small individual metal blanks.

3. Exposure Sites

Three of the 4 - 7/16 inch square specimens of each enamel

were exposed on the roofs of Federal Government Buildings in

New York, New York, Los Angeles, California; and Washington,

D.C. ; as well as the roof of the Stores Department Building in

Montreal, Canada. Three of the 4 X 6 inch specimens of each

enamel were exposed at a ground site of the International

Nickel Company's Corrosion Laboratory at Kure Beach, North Carolina - 80 feet from the ocean. In addition to the exposed

specimens, three specimens of each enamel were designated as

"storage" enamels. These enamels were set aside in a dry,

dark place and allowed to age indoors. The remaining 69 specimens

of each enamel were kept for use in laboratory tests and for

the development of new test methods, as needed.

4. Cleaning of Specimens

A standard cleaning process was selected to remove all

dirt, fingerprints, etc. from the enamel surface before it

was measured for gloss and color. The cleaning treatment

consisted of 1) scouring 30 strokes with a sponge that had

been dampened with a one percent, by weight, solution of tri-
sodium phosphate and sprinkled with calcium carbonate, 2)

rinsing with tap water, 3) rinsing with distilled water, and

4) rinsing with alcohol.

5. Gloss and Color

The ^5° specular gloss of the enamel s was measured at

four orientations near the center of the specimens both before

and after exposure. The gloss is reported as the percentage

gloss retained after exposure.

The color change of the enamels was measured with a color difference meter. One of the three storage specimens

was used as the standard in measuring the color difference.

This was done to obtain maximum efficiency with this type of

instrument. The storage specimens were, in turn, measured

against calibrated NBS color standards to determine whether

the enamels changed color during storage. The color change

is reported as color retention, which is 100 minus the color

difference in NBS units.

RESULTS

1. Appearance and Cleaning of Specimens

When the specimens were returned to the laboratory at

the National Bureau of Standards for their one-year inspection;

those exposed at Kure Beach appeared clean while those exposed

at Washington, Montreal, New York and Los Angeles had increasingly

heavier dirt films on them. These dirt films were easily removed

from all specimens by the cleaning procedure outlined above.
This v as somewhat unexpected since the specimens exposed for

six months at New York required a severe scouring treatment to

remove the adherent dirt film. The ease with which the dirt

film was removed between six-months' and one-year's exposure

is probably due, at least in part, to the increased rainfall

during this time.

2. Gloss and Color

The gloss and color of each enameled specimen after oneyear's exposure was measured as described above. The avaerage

percentage gloss retained and color retention for the three

specimens of each enamel exposed at each site as well as the

storage enamels are given in Table 2.

Since small changes in color are more noticable than

large changes in gloss, the data in the remainder of this report

will be presented primarily on the basis of color retention.

The percentage gloss retained will be presented as supplementary

information

.

3. Comparison of Exposure Sites

The average values for color retention and percentage

gloss retained for all ename Is exposed at each site are given

2 /

in Table 3. A two-sided sign test performed on the data in

Table 2 indicated that the gloss and color were not effected

by the weather in the same manner. Thus when the color data

were analyzed, the enamels exposed at Kure Beach underwent significantly more color change than those exposed at any other site.
The enamels exposed at New York, Washington, and Los Angeles

showed significantly less color change than those exposed at

Kure Beach hut were not different from each other while the

enamels exposed at Montreal showed a significantly smaller

color change than those exposed at all the other sites. This

is illustrated in Figure 1.

When the gloss data were treated in a similar fashion,

different results were obtained. These data indicated that

the atmospheric conditions at Kure Beach, Washington, and Montreal. caused the most change in an enamel's gloss while the

atmospheric conditions at New York and Los Angeles, respectively,

caused significantly less change in the enamel's gloss. This is

also illustrated in. Figure 1.

With this apparent difference in the degradation of

gloss and color of the enamels exposed at the different sites,

it is important to recall that changes in color are more noticable than changes in gloss. Therefore the color change, or

retention, will be emphasized in this report.

Correlation of Color Retention with Boiling Acid Solubility

The relationship between color retention and boiling acid

solubility for all the enamels, except the reds, exposed at all

sites is illustrated in Figure 2. (The red enamels were omitted

!_/

because they failed the lS-second nitric acid spot test and

would not normally be used for outdoor exposure.) It can be

noted that the effect of boiling acid solubility on color

retention is greatest at the most aggressive site, Kure

Beach. At this site, which as an extremely corrosive atmosphere,
only those enamels with very low acid solubilities : - h o u 1 cl b e used

.

In an effort to stress the improvement in quality that

could be effected if the boiling acid solubility limits were

reduced from 20 to 10 tng/in 2

, two sets of data will be given

in most of the following tables; one set will include all the

enamels in the test while the other will include only those

enamels with boiling acid solubilities under 10 mg/in 2 .

"5 . Comparison of Enamel Colors

The average color retention and percentage gloss retained

for the nine different colors Included in this test are

presented in Table 4. It is evident from observation of this

table that some of the enamel colors, light green and brown,

have excellent color retention even at the most aggressive

site, Kure Beach, while another color, red, had poor color retention at all exposure sites. The relatively poor color

retention of the red enamels is not a cause for too much

concern since it could have been predicted by the 15 -seccnd

nitric acid spot test which is included in the specification

__3/

for architectural porcelain enamels on aluminum. Because these

enamels had poor color retention, and because the poor color

retention could be predicted, the values for the red enamels

will be omitted from many of the following tables.

The low color retention of the black and dark green

enamels exposed at the most aggressive site, Kure Beach, was

unexpected. These values were greatly improved (see Table 5)

when only those enamels having boiling acid solubilities under
10 mg/in^ were considered. This again suggests that enamels

with lower boiling acid solubilities should be used, whenever

possible, to insure good color stability.

6. Comparison of One- and Two-Coat Enamel Systems

The average color retention and percentage gloss retained

for the one- and two-coat enamel systems are presented in

Tab le . These data indicate that the color retention of the

two-coat systems is slightly better than for the one-coat

systems. This may be due to better weather resistance of the

two -coat enamels or it could be due to the i nheren t differences

in the colors that were produced in one-and two-coat enamels.

For example; the one-coat enamels were primarily dark colors

while the two-coat enamels were primarily pastel colors. Indeed

the only completely valid comparison of these coating systems

would be to compare the white enamels that were produced in both

one- and two- coat systems. This comparison follows:

No. of Kure New Wash- Lo s MontCoats Beach York ington Angeles real

One 97,7 98.3 98.9 98.9 99.1

Two 98.1 98.7 99,0 98.9 . 99.0

Thus it can be seen that when the same enamel color is compared

in both one - and two -coat systems, it is extremely difficult

to say. at this time , that one coating system is better than

the other.

7 . Comparison of Enamels in Different Gloss Ranges

The average color retention and percentage gloss retained

for the enamels included in the three gloss ranges is given

in Table 7* When all enamels are considered, there are only
slight differences in the average color retention of the enamels

included in these three gloss ranges with the exception of the

high-gloss enamels exposed at Kure Beach. When only the enamels

with boiling acid solubilities under 10 mg/in are considered,

the differences in color retention are minimized and it could

be said that the initial gloss of the enamel does not have any

bearing on its color retention after one-year's exposure.

Observation of the gloss data in Table 7 indicates that

the low gloss enamels have the highest gloss retained values

followed by the medium and high gloss enamels. This would be

acceptable if the low and medium gloss enamels did not increase

in the percentage gloss retained between six-month's and oneyear's exposure. This increase in gloss could be explained in

several ways; 1) the enamel is being selectively erroded either

by the weather or by the scouring action during the removal

of the adherent dirt film. This selective removal of enamel

might result in a more nearly plane surface which would tend

to increase the ^5° specular gloss, 2) invisible films could

be forming on the surface of the specimens which would produce

a doubly reflecting surface that would tend to increase the

gloss, or 3) the gloss meter may not be sensitive enough to

accurately measure changes in low gloss enamels. At this time

it is impossible to say which one of these mechanisms, if any,

is responsible for the increase in gloss noted for these specimens.

These specimens will be carefully monitored in future inspections

to see if this unexpected trend continues.
This increase in gloss of the low and medium gloss enamels,

uncoub tedly had some effect in producing the non-correlation

of the site-severity ratings (section 3 of results).

8. Spall Resistance

A "fish-scale" type of spalling was observed on several

of the 153 specimens exposed at each site. This spalling was

noted on 8 specimens exposed at Kure Beach, 17 at New York,

1 at Washington, and 22 at both Los Angeles and Montreal. These

areas of spalling, while plainly visible on close examination

probably would not be objectionable on the side of a building

or a sign. In no case was there l/8 inch of bare metal visible

but in some cases the bare metal and the fractured enamel would

measure more than l/8 inch. Since this spalling is still confined to small areas, it is not thought to be a serious defect

at this time.

9. Effect of Exposure Time on Color Retention

The effect of exposure time on the average color retention

of all the enamels included in this test is illustrated in

Figure 3 . Here it can be seen that the color change is the

greatest during the first six months' exposure and then the

rate of color change decreases for the enamels exposed at all

sites except Kure Beach where the color continues to change at

a rapid rate.

10. Comparison of Enamels in this Test with Those in Previous

Exposure Tests

The average color retention and percentage gloss retained

for the acid-resistant enamels on steel and the enamels on

aluminum included in the 1956 test as well as the enamels on
aluminum included in this test are presented in Table 8. It

can be seen that the enamels on aluminum exposed at Washington

and Los Angeles in this test have better color retention than

those included in the 195 6 test and they have color retentions

as good as the acid resistant enamels on steel included in the

19

5

6 test. When considering only the non-red enamels having

acid solubilities under 10 mg/in^ the enamels in this test

exposed at these sites have slightly better color retention

than the acid-resistant enamels on steel included in the 19 5 6

test.

This, however, does not hold true for the enamels exposed

at Kure Beach. When all of the enamels in the 1964 test are

considered, their color retention is somewhat poorer than

either the enamels on aluminum or the acid-resistant enamels

on steel in the 1956 test. When considering only uhe non-red

enamels with boiling acid solubilities under 10 mg/in^, the color

retention of the enamels on aluminum included in the 1964 test

is better than the enamels on aluminum included in the 195 ' test

but it is somewhat lower than the acid-resistant enamels on

steel exposed at this same site in the 1956 test. This again

supports the statement that only the very best enamels, having

low foiling acid solubilites, should be used for coastal

installations

.

SUMMARY

After one-year's exposure at Kure Beach, North Carolina;

New York, New York; Washington, D.C. ; Los Angeles, California;

and Montreal, Canada the changes in gloss, color and general

surface conditions of triplicate specimens of 51 porcelain
enamels on aluminum were determined. A s ummary of the more

important findings follows.

1. All specimens were easily cleaned.

2. The enamels exposed at Kure Beach retained less color

than those at any other site, while the enamels exposed

at Montreal retained the most color. The enamels

exposed at New York, Washington and Los Angeles were

intermediate between these two extremes and did not

differ significantly from each other.

3. The color retention correlated well with the boiling

acid solubility.

U. For the best wea therabi li ty , consideration should be

given to limiting the boiling acid solubility to 10

mg/in2 .

5. The red enamels were the only ones having boiling acid

p solubilities under 10 mg/in^ that showed large color

change s

.

6 . There were no appreciable differences between the color

retention of enamels produced with one or two coats of

ename 1 or among enamels having low, medium, or high

initial gloss

.

7. There was no extensive spalling noted at this time.

8. The enamels in this test with boiling acid solubilities

2 under 10 xsxg/ln had better color retention than the

enamels on aluminum included in the 1956 test.
Table 1. Summary of Initial Data for Porcelain Enamels on Aluminum

Enamel Visual Color Nominal k5 o Number Thickness Acid

1 Gloss Specular of Coats mils Solubility

Gloss mg/in^

AA-A White High 70.1 Two 4.5 5.5 AA-B White High 74.2 Two 4.3 5.9 AA-C White High 71.5 Two 3.44 5.0 AA-D White High 71.9 Two 6.5 12.7

AB-A White Medium 50.8 Two 4.0 7.2

AB-C White Medium 55.o Two 4.0 4.9 AB-D White Medium 20.9 Two o.2 7-9

AS-A White High 74.5 One 3.8 6.4

AC-B White High 71.8 One 2.8 11.3

AC-C White High 70.5 One 3.3 9.9

AD-A White Medium 55.0 One 2.8 6.2 AD-B White Medium b8.3 One 4.3 6.7 AD-C White Medium 42.4 One 3-2 7.1 AD-D White Medium 34.9 One 2.7 12.4

AE-A Black High 75.6 One 2.4 6.5 AE-B Black High 78.0 One 1.6 10.1

AE-C Black High 78.1 One 2.0 12.1. AE-D Black High 75-0 One 3.4 15.5

AE-A Black Medium 78.4 One 1.5 14.2

AF-B Black Medium 58.5 One 2.7 9-0

AF-C Black Medium 76.8 One 3.1 10.1

AG-B Black Low 26.0 One 3.0 12.5 AG-C Black Low 12.o One 2.0 7.5

AH-A Red High 46.9 One 2.8 7.4 AK-B Red High 85-3 One 3.1 6.8 AH-C Red High 65.6 One 3-1 6.5 AH-D Red High 82.0 One 1.9 10.5

AO-A Dark Green High 78.8 One 3.2 19.9 AO-B Dark Green High 79.3 One 1.6 10.1 AO-D Dark Green High 78.3 One 2.1 17.0

AP-A Light Green Medium 42.4 Two 6*4 12.3 AP-B Light Green Medium 36.5 Two 4.1 6,4

AP-C Light Green Medium 30.2 Two 4.0 6.2

AP-D Light Green Medium 45.3 Two b.4 10.0

AR-A Light Green Low 9-6 Two 3.2 4.4 AR-B Light Green Low 7.3 Two 2.7 5.5 AR-C Light Green Low 5.7 Two 4.3 8.1

AS-A Gray Medium 64.9 Two 5.0 13.4 AS-B Gray Medium 61.6 Two 5.5 7.4 AS-C Gray Medium 62.2 Two 3.9 5.4

AT-A Blue Medium 32.9 Two 4.4 6.2 AT-B Blue Medium 54.8 Two 3.6 7.0 AT-C Blue Medium 62.4 Two 2.9 6.1

AU-A Brown Medium 50.0 Two 7.2 5.3 AU-B Brown Medium 35.4 Two 6.4 7.5 AU-C Brown Medium 46.6 Two 4.4 7.6

AW-A Yellow Medium 62.4 Two 5.8 7.8 AW-B Y ellov Medium 63.I Two 4.1 8.7 AW-C Yellow Medium 80.9 Two 5.0 18.6

AZ-A White High 72.0 Two 4.2 9.5 AZ-B White High 71.2 Two 2.7 5.2

Acid. Spot Test Ratings

A

A

AAAA

BAA

AAAAA

AA

B

BA

A

A

A

B

B

B

C

BA

A

B

BB

AA

A

B

AA

A

AA

A

AAA

A

A

A AA

A

AA

A

A

A

AA
Table 2 . Summary of One Year's Exposure Data for Porcelain Enamels on Aluminium

Enamel Kure Beach

Gloss Color New YorkGloss Color WashingtonGloss Color

Los Angeles

Gloss Color MontrealGloss Color

Storage

Gloss Color

AA-A 95.2 98.1 96.5 99.3 91.6 99-6 97.8 99-3 90.4 99.6 98.2 99.9

AftB

87.5 98.7 93.5 99-

91.5 99-3 100.9 99.0 93-2 99.4 98.4 99.8 AA-C 107. 4 97.0 89.0 99-0 90.8 98.8 90.8 98.5 87.6 99.0 98.7 99.8 AA-D 33-0 97.0 97.8 97.4 92.5 97 .9 100.4 96.8 93 .1 97.8 98.7 99.7

Air -A 00.4 97.8 94.2 97.3 80.9 98.3 uo 0 3 96.

u

85.7 98.5 96.7 99.9

AE-C Jo . 4 99.1 84.4 99.0 83.0 99.5 87.9 99-3 32.7 99.4 9o.9 99.8 AB-D dO.

2

97.o 112.1 98.4 92.o 98.o 98.1 99.1 95.9 98.9 97.1 99.9

ACA

90.7 98.7 93.1 99.3 91.8 99-2 101.0 98.7 93.1 99-3 98.8 99.7 AC-B 37.3 98.1 98.4 97.1 90.2 98.8 101.3 99.2 97.1 98.4 98.8 99-7

AC-C o5.3 9o.9 96.8 98.4 92.1 98.6 98.1 98.8 94.1 98.9 99.5 99.8

AP-A 9o.9 98.o 99-9 99-2 91.1 99.4 95.7 99-3 91.1 99.3 98.5 99.8 AD-B 93-

a

98.3 94.5 99.2 83.9 99.6 9M 99.3 88.2 99.5 99.2 99.9 AD-C 91.3 9b.

9

106.4 97.9 90.3 98.8 95.4 98.4 9^.5 98.9 98.0 99.9 AD-D 5a,

o

97.3 114.6 9b.

7

9b. 5 98.1 103.1 98.9 100.3 99.1 98.8 99-9

AE-A Od.4 94.3 8O.3 99.1 80.5 98.8 80.5 97.2 80.2 99.9 96.5 99.7

AiS-B 53.

a

09.I 83.7 99-4 62.9 99-8 80.6 99.1 95.1 99.0 97.7 99.7

AE-C bo.2 92.9 83.7 99-0 85.0 99.o 89-9 99.2 85.1 99-0 97.7 99.7 AE-D 37.

a

7b.o 79.9 90.2 7o.4 90.4 03.2 97.2 63.O 98.4 97.1 99.0

Aj -n o7-9 OO.o • 2.1 57.7 30

.

0 95; • 1 84.3 97- -1 84.3 96.4 98.1 99.9

>; • J Gd . 7 95.3 < K . 4 91.7 99.0 9o.

5

99.'+ 95 0 3 99.7 98.1 99-9 7t.8 95-1 03.3 98.1 62.0 99. 1 66.6 98.3 85.4 99.4 97.9 99.7

AG-B 63.7 88.2 100.4 98.5 97.8 98.7 103.1 98.1 100.5 98.5 96.8 99.7

AG-C 112.8 97.1 101.0 98.1 100.8 99.5 103.8 99.0 97.0 99.5 92.3 99.6

AE-A 79-3 93.5 121.3 97.1 96.0 97.6 113.2 96.9 103.6 97.4 100.1 99.4 AH-B 44.8 83.1 75.

b

95-1 70.0 94.0 77.6 94.4 75.7 95.2 99-6 99.7

AH-C 59.2 86.3 75.6 90.7 68.

5

91-5 77-4 91.4 93.6 91.8 99.7 99.7 AE-D 37-8 70.2 77.0 90.8 70.6 87.2 81.8 88.4 77.6 88.1 98.9 99.6

AO-A 60.9 91.7 73.5 99-0 79-3 99-0 83.3 99.2 81.4 99.3 98.8 99.9 AO-B 67.0 97.3 83.1 99-3 82.7 99.7 86.0 99.4 83.1 99.5 98.3 99.6 AO-D 50.8 92.0 79.1 98.6 80.7 98.0 84.2 98.6 84.9 99-0 97.3 99.8

AP-A ao.4 95.2 104.9 99.5 93.'

4

99.2 97.4 99.3 94.8 99-3 98.3 99.8 AP-3 07.1 90.7 94.0 99-4 8I.9 99.4 89.0 99.

b

82.0 99 -

h

98.0 99.8

AP-C 84.1 98.9 98.9 99.7 83.9 99.1 91.3 99.

b

83.9 99-6 97.5 99.8 AP-D dO.

9

97.1 100.8 99-3 93-^ 99.0 95.2 99-3 94.7 99*3 97.8 99.9

AR-A 120.2 99.u 130.4 99.3 104.6 99.4 122.2 99-0 10o»5 99.7 90.8 99.7 AR-B 9o.l 90 .

1

110.9 9 • 7 74.7 99 ° 0 31.7 99.0 73.o 99-7 91.4 99.7 AR-C 105.9 98.3 o4„o 98.0 75 • 6 99.0 81.6 99-4 69.0 99.o - 89.9 99.8

AS-A 59-5 9b.2 80.3 99.3 86.4 99.0 93-0 99.o 89.7 99.4- 97.7 99-8

AS-B do. 4 97.3 84.5 99.4 82.3 99.1 84.6 99.3 82.3 99.3 98.9 99.6

AS-C 97.7 99.6 89.9 99.5 92.2 99.7 95-5 99.6 89.1 99.6 9«.9 99.6

AT-A 93.0 97.4 94.1 98.8 83.2 98.9 91.0 99.3 83.1 99.1 98.8 99.9 AT-B 93.^ 94.9 95.6 98.8 94.1 99.0 95.5 97.8 90.9 99.1 98.6 99.9

AT-C d2.0 9b. 2 63.0 99.1 79-2 99.1 84.0 98.9 79-9 99-^ 98.2 99.7

AU-A 09.8 99.4- 90.7 99-8 64.9 99.7 92.5 99.7 83.4 99.7 98.7 99.6 AU-B 93-^ 99.^ 108.1 99.4 91.8 99.6 94.9 99.7 89.7 99-6 97.6 99.6

AU-C 94.7 99.6 98.0 99-6 93-9 99.^ 97.9 99-8 93.5 99-8 96.2 99.

b

AW-A 80.1 98.7 85.1 99.5 81.5 99.4 85.8 99-5 83.5 99-

b

98,2 99-9

AW-B 79.2 97.3 94.3 99.2 92.4 99.0 95.2 99.3 92.7 99-3 98.1 99.7 AW-C 47.6 95.9 85.4 99-1 81.4 99.0 90.3 99.5 86.3 99.^ 99.0 99.8

AZ-A 50.1 98.9 99.2 99.0 91.5 99.2 102.1 99-1 98.0 99.2 100.2 99-8 AZ-B 110.7 97.8 64.1 98.9 91.2 98.9 98.0 98.8 89.2 99.7 99,b

Average 77.9 95.1 93.2 98.4 86.7 98.6 92.9 98.7 88.3 98.8 97.8 99.7

Visual Color

White

White

Whi te White

White

White

White

White

White

White

White

White

White

White

Black

Black Black

lilac k

Bj_ack Black Black

Black

Black

Red

Red

Red Red

Dark Green Dark Green Dark Green

Light Green Light Green

Light Green

Light Green

Light Green

Lignt Green

Light Green

Gray- Gray

Gray

Blue

Blue Blue

Brown Brown

Brown

Yellow

Yellow

Yellow

White

White
Table 3. Average Percentage Gloss Retained and Color

Retention of Porcelain Enameled Aluminum ab

t li e Differ e i c, Exp o sure £ 1 ten

Exposure Site Color Retention Perce:

Gloss Re

Kv.re Eeacli -CO 95.1 77. S' New York 98.4 93.2

W a s h i n g t o n 9 8.6 P r -7

( . i Los Angeles 98.7 92.9

M ontreal 98.8 88.3

Storage 99.7 97.8
Table 4. Average Color Retention and Percentage Gloss Retained for the Different Colors of Porcelain

Enameled Aluminum after One Year's Exposure.

ALL ENAMELS

Color Retention

Ename

1

Color

Kure Beach New York Washington Los Angeles Montreal Storage Average of Exposed

Enamels

Red 83.3 93.4 92 .6 92.8 93.1 99.6 91.0

Black 89.9 98.6 98.9 98.4 99.2 99.7 97.0

Dk. Green 93.7 99.8 93.9 99.1 99.3 99.8 98.0

Blue 96.2 98.9 99.0 98.9 99.0 99.8 98.7

White 97.9 98.5 99.0 98.9 99.0 99.8 98.9

Yellow 97.3 99.3 99.1 99.4 99.4 99.8 98.9

Gray 97.7 99.4 99.3 99.5 99.4 99.7 99.1

Lt . Green 98.1 99.2 99.3 99.5 99.5 99.8 99.1

Brown 99.5 99.6 99.6 99.7 99.7 99.6 99.6

Percentage Gloss Retained

Ename

1

Color

Kure Beach New York Washington Los Angeles Montreal Storage Average of Exposed

Enamels

Red 55.3 87.3 76.4 87.5 82 .6 99.6 77.8

Black 70.0 87.5 86.7 90.5 89.9 96.9 84.9

Dk. Green 59.6 80.2 85.0 84.5 83.1 98.1 78.4

Blue 89.7 90.9 85.5 90.2 84.6 98.6 88.2

White 79.5 95.9 90.3 97.5 92.1 98.6 91.1

Yellow 69.0 88.3 85.0 90.4 87.5 98.4 84.0

Gray 81.3 87.6 87.0 91.0 87.0 98.5 86.8

Lt . Green 95.8 104.7 89.7 94.1 86.6 94.8 94.2

Brown 92.6 93.8 90.2 95.1 88.9 98.2 92 .1
Table 5. Average Color Retention and Percentage Gloss Retained for the Different Colors of Porcelain

Enameled Aluminum after One Year's Exposure.

ENAMELS WITH BOILING ACID SOLUBILITIES UNDER 10 MG/ IN^

Color Retention

Ename

1

Color Kure Beach New York Washington Los Angeles Montreal Storage Average of Exposed

Enamels

Red 87.6 94.3 94.4 94.2 94.8 99.8 93.1

Black 93.4 98.5 99.1 98.5 99.7 99.7 97.4

Dk. Green — — — — — — —

Blue 96 .2 98.9 99.0 98.7 99.2 99.8 98.4

White 98.0 98.9 99.1 98.9 99.2 99.8 98.8

Yellow 98.0 99.4 99.2 99.4 99.5 99.8 99.1

Gray 98.5 99.5 99.4 99.5 99.5 99.6 99.3

Lt. Green 98.9 99.1 99.4 99.6 99.6 99.8 99.3

Brown 99.5 99.6 99.6 99.7 99.7 99.6 99.6

Percentage Gloss Retained

Enamel

Color

Kure Beach New York Washington Los Angeles Montreal Storage Average of Exposed

Enamels

Red 61.1 90.8 78.3 89.4 91.0 99.8 82 .1

Black 79.9 92.2 91.0 93.6 90.8 95.6 89.5

Dk. Green —

— — — — — —

Blue 89.7 90.9 85.5 90.2 84.6 98.6 88.2

White 87.9 94.2 96.5 96.5 91.1 98.6 93.2

Yellow 79.7 89.7 87.0 90.5 88.1 98.2 87.0

Gray 92.1 87.2 84.4 88.8 86.0 98.3 87.7

Lt . Green 100.3 105.5 84.2 93.3 83.3 93.5 93.3

Brown 92.6 93.8 90.2 95.1 88.9 98.2 92.1
Table 6. Average Color Retention and Percentage Gloss Retained for One and Two Coat Systems of Porcelain

Enameld Aluminum after One Year's Exposure.

ALL ENAMELS

Color Retention

Number

of Coats Kure Beach New York Washington Los Angeles Montreal Storage Average of Exposed

Enamels

One* 93.3 98.5 98.9 98.7 99.2 99.8 97.7

Two 97.9 99.1 99.2 99.2 99.3 99.8 98.9

Percentage Gloss Retained

Number

of Coats

Kure Beach New York Washington Los Angeles Montreal Storage Average of Exposed

Ename Is

One* 68.2 95.1 87.5 92.5 89.7 99.7 86 .6

Two 86.0 91.2 87.7 93.9 88.1 99.8 89.4

ENAMELS WITH BOILING ACID SOLUBILITIES UNDER 10 MG/ IN*

Color Retention

Number

of Coats

Kure Beach New York Washington Los Angeles Montreal Storage Average of Exposed

Enamels

One* 96.1 98.7 99.1 98.7 99.4 99.8 98.4

Two 98.2 99.1 99.3 99.2 99.4 99.8 99.0

Percentage Gloss Retained

Number

of Coats Kure Beach New York Washington Los Angeles Montreal Storage Average of Exposed

Enamels

One* 77.9 91.6 88.2 92.7 89.4 97.8 88.0

Two 91.2 95.0 87.4 93.6 87.3 97.4 90.9

*The red enamels were omitted when the average values for the one coat systems were calculated because they

failed the 15-second nitric acid test and would not be recommended for architectural purposes.
Table 7„ Average Color Retention and Percentage Gloss Retained for the Different Gloss Ranges of Porcelain Enameled Aluminum Exposed for One Year.

ALL ENAMELS

Color Retention

Gloss

Range

Kure Beach New York Washington Los Angeles Montreal Storage Average of Exposed

Enamels

Low 97.0 98.5 99.1 99.2 98.5 99.8 98.5 Medium* 97.

a

99.1 99.2 99.2 99.1 99.8 98 „ 8

High* 93.9 98.7 98.9 98.7 99.4 99.8 97.7

Percentage Gloss Retained

Gloss Range

Kure Beach New York Washington Los Angeles Montreal Storage Average of Exposed

En ame 1 s

Low 93.6 106.1 90.0 97.3 90.0 99.7 95.4

Medium* 85.7 94.2 88.0 92.6 88.7 98.3 89.8

High* 67.3 82 .2 86.1 92 .2 88.3 98.4 83.2

ENAMELS WITH BOILING ACID SOLUBILITIES UNDER 10 MG/ IN

2

Color Retention

Gloss Range

Kure Beach New York Washington Los Angeles Montreal Storage Average of Exposed

Enamels

Low 98.2 98.8 99.3 99.4 99.4 99.8 99.0

Medium* 97.5 99.1 99.3 99.2 99.4 99.8 98.9

High* 97.6 99.1 99.1 98.7 99.3 99.8 98.8

Percentage Gloss Retained

Gloss Range

Kure Beach New York Washington Los Angeles Montreal Storage Average of Exposed

Enamels

Low 92 .5 105.7 87.9 95.7 87 a 94.0 93.8

Medium* 87.4 93.7 87.5 92 a 87.8 98.3 89.7

High* 75.9 89.1 90.1 96.9 90.7 98.8 88.5

*The red enamels were omitted when the average values for the medium and high gloss enamels were calculated

because they failed the 15-second nitric acid test and would not be recommended for architectural purposes.
Table

8.

Comparison

of

the

Color

Retention

and

Percentage

Gloss

Retained

for

the

Enamels

in

the

1956

and

1964

Exposure

Tests

'd CO

0) 0)

S3 r—

1

O IT\ On OJ P CO cd • • 0 . <s o bO o VO CM -e- P h3 S3 on r— ON on

CD <

03

co

cno » S3 CO to- co H 43 O 0 • • 0 O w -P on CM VO CO

cd bO CO c— CO CO

<D & S3 bD P

cd -P

S3<D 43 i—

l

t- ON LTN o cy u • e • 0 H H cd i—

1

LT\ r- ON

CD S3 cd CO c— 13- CO

PH Ui FQ

CD

0)

CO rH VO PO t— rH O CD . . 0 • i-l bO CO CO co On

S3 On ON ON On <

S3op

P 1 S3 43 O CO CM VO CM

<D CO p • 0 • • -P cd bO CO 00 co ON

CD I3£ S3 ON On ON On

03 P

H

O

r—

i

43 O CD o ON t— rH t— o 0: ed 0 9 « 0 P CD 00 VO r- W FQ ON On On' On

CM

S3 P

i 43 t3 co -P co p P CD bQ

CO •s rH P O P 0

tH I—t -p •s-P », P <D «. P > < -p

CO <D co B co S co s B co p O

CO (D CD CD S3 CD S3 (D cd S3 4) CO bOH rH

rH 03 P EH S3 EH S3 EH S3 S3 Eh rH S3 P

a; i CO P P W P CD P ,Q H

0 t3 VO 0 VO S -=f S -e 0 rH S3 CD

cd P bo U"N S3 LTN S3 VO rH S3 VO cd P <H t3

S3 o S3 On H On rH Q\ rH rH ON S3 O O S3 W < P rH < H <3 rH < < H W FQ CO S3
COLOR

RETENTION

PERCENTAGE

GLOSS

RETAINED 4

£3P • co a P o 4S

CO •H

<D

U

-P 4

•H Pi w 03

0) S p P £ P

co •H O E

Pi P X rH W < 4 td £3 4 P 1—I 4

«H E O cdP

CO

W Po P

4) •rH 4-i ad

4-i i—1 W 4O

4) P > o

Ph

p

a) p3

rH flj

p 4 CO TP 4 p K O o ^ +> W Pi o P 4 4 X o 4 pq -P W m P

«HO o p p o O -H •H P

-P

p

cc 4

-p

p

p 0)

a; «

to4 P P o

Pi rH 4 o K OI TP

ce £ U C3

£3 co PU co C O

Pi r—I O O i—1

4)££

W)

fp
COLOR

RETENTION

80IL1N© AGIO SOLUBILITY, mg /In*

Correlation of the Color Retention of Porcelain Enamels

on Aluminum with their Boiling Acid Solubility.

Figure 2.
TIME, YEARS

Figure 3. The Effect of Exposure Time on the Color Retention of

Porcelain Enameled Aluminum.