NATIONAL BUREAU OF STANDARDS REPORT

9042

PROGRESS REPORT

October 1 through December 31, 1965

Development of Methods of Test

For Quality Control of Porcelain Enamels

PORCELAIN ENAMEL INSTITUTE RESEARCH ASSOCIATESHIP

NATIONAL BUREAU OF STANDARDS

WASHINGTON, D.C.

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
Th- National Bureau of Standards is a principal focal point in the Federal Government for assuring

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 stand- ards 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 festinz materials, mechanisms, and structures, and making such tests as may be 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 Government; 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 four 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.**

Central Radio Propagation Laboratory.* Ionospheric Telecommunications. Tropospheric Tele- communications. Space Environment Forecasting. Aeronomy.

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

NBS PROJECT

42104-12-4216270

NBS REPORT

9042

PROGRESS REPORT

October 1 through December 31, 1965

Development of Methods of Test

For Quality Control of Porcelain Enamels

PORCELAIN ENAMEL INSTITUTE RESEARCH ASSOCIATESHIP

NATIONAL BUREAU OF STANDARDS

WASHINGTON, D„C.

IMPORTANT NOTICE NATIONAL BUREAU OF f for use within the Government Approved for public release by the

and review. For this reason, Director of the National Institute of

whole or in part, is not auth , „ ,

. r > Bureau of Standards, Washin Standards and Technology (NIST)

the Report has been specifical on October 9, 2015

ress accounting documents intended

is subjected to additional evaluation

re listing of this Report, either in

the Office of the Director, National

jy the Government agency for which

copies for Its own use.

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

PROGRESS REPORT

October 1 through December 31, 1965

PROCELAIN ENAMEL INSTITUTE RESEARCH ASSOCIATESHIP

NATIONAL BUREAU OF STANDARDS

WASHINGTON, D. C.

SUMMARY

A tentative test procedure for cleanability of porcelain enamels

has been developed. This procedure consists of mechanically soiling

the specimen with a known amount of soil containing a fluorescent

tracer, mechanically cleaning the specimen for a specified time and

then determining the amount of retained soil by analytical procedures.

Many of the variables concerned with determining the reproducibility of the test have been studied and several different materials

have been subjected to the test procedure. The test procedure has

sufficient reproducibility to detect significant differences between

21 of the 29 glossy enamel surfaces tested.

The procelain enamels on aluminum exposed for six months at

Kure Beach-80, Washington, New York City and Montreal have been

inspected. The changes in gloss and color indicate that the Kure

Beach site produces more severe changes in the enamel than the other

three sides. The red enamels showed poor color stability at all sites.

Poor color stability was indicated by all the red specimens failing the

test for color stability currently in the architectural specification

for porcelain enameled aluminum. There were no appreciable differences

in color or gloss retention between the different gloss and thickness

ranges after six months' exposure.
- 2

-

Storage specimens of the Nature-tone enamels were tested with

the direct-current, high-voltage test equipment. The test results

indicated that the best separation between the enamels that did and

did not rust was obtained at 2 kV. However, the large percentage of

good enamels that failed at this voltage led to an investigation of

the relative corrosion rates of mild steel specimens exposed at Kure

Beach-80 and other sites in the United States. This investigation

revealed that specimens exposed one year at Kure Beach-80 had as much

corrosion as would occur in 5-7 years at many industrial locations

in the United States.

I. CLEANAB I LITY

INTRODUCTION

The use of performance criteria for building materials and domestic

appliances is a logical way to compare products of different materials

intended for the same service. The development of these criteria and

of suitable evaluation procedures is receiving increased attention both

among governinent procurement agencies and the industries supplying the

needed materiel. The establishment of acceptable levels of performance

must be preceeded by the selection of testing methods to measure the

performance of products regardless of the material from which they are

formed

.

One of the current goals of the Porcelain Enamel Institute research

effort is the selection and development of a testing procedure to evaluate the cleanability of porcelain enamels and other competitive building

and appliance systems.
-3-

The procedure under development involves: (a) the application of

a standard soiling agent to a specimen surface, (b) the partial removal

by a standardized Cleaning treatment and (c) the determination of the

amount of retained soil which is used as an inverse index of the property

of cleanability

TENTATIVE TEST PROCEDURE

The results and discussion that follow, in later paragraphs, deal

with variations of the individual parts of a tentative test procedure

and the application of this technique to specimen surfaces of porcelain

enamel and other materials. This section describes the sequence of

test procedures used, in order to provide a frame of reference for the

results and later discussion.

1. Tha Soiling Agent.

The standard soil used was described in a previous report and

consisted of:

Ingredient Amount in Percent

by Weight

BBOT^ 3.3

Powdered Graphite 32.8

Mineral Oil 63.9

a / 2,5-bis-[5' - tert-buty lbenzoxazolyl (2 ') ]-thiophene.

2. The Cleanability Test Procedure.

a. Specimens were prepared for test by a cleaning sequence which

involved scrubbing with a cellulose sponge moistened with a one percent

solution of trisodium phosphate until a "water break" was not observed.
-4-

The specimens were then washed thoroughly with a household detergent

and rinsed with running tap water, distilled water and absolute alcohol

and allowed to dry in a near vertical position.

b. A cleaned specimen was attached, face up, to an 8-inch lapping

wheel with tape across the corners as shown in Figure 1.

c. A weighed amount of the premixed graphite and BBOT was added

to three drops of mineral oil on the specimen surface. The dry components and the oil were blended on the specimen with a spatula.

d. The soil was uniformly distributed over a 3- inch diameter

central area of the specimen by the combined action of the rotation of

the specimen with the lapping plate, and the back- and- forth motion of

the padded brass head.

e. A mechanical cleaning action was provided through the use of

a tissue-covered, 2 1/4- inch diameter brass disc which operated with

the same action as described above. The tissues were changed at

specified intervals.

f. A circular area, 1 1/4-inches in diameter, at the center of

the cleaned specimen was covered with a teflon mask. All of the specimen surface except the covered axea, was cleaned by hand-rubbing and

solvent action, first with a tissue moistened with toluene, followed

with a clean, dry tissue. This cleaning operation was repeated two

more times, after which the mask was removed. At this stage, the soil

retained on the specimen after the mechanical cleaning operation

(e above) had been removed except for the masked spot.
-5-

g. The oil and BBOT from the "spot" on the specimen surface was

extracted with toluene which is a good solvent for these reagents. The

graphite of the original soil was inert to toluene and remained on the

specimen. A 150-ml 2-inch diameter glass reagent bottle, from which

the bottom had been removed, was clapped against a 1/16- inch thick teflon

gasket and the specimen. A weighed portion of toluene was poured into

the reagent bottle which was then closed with a standard-taper glass

stopper. The toluene was repeatedly agitated during a two minute period

by up-ending and swirling the extraction d evice and specimen.

h. A small portion of the toluene solution was poured into a

clean beaker and transferred to a 5 ml cuvette so that the intensity

of the fluorescent solution could be measured in the fluorometer. The

concentration of extracted BBOT, in micrograms per ml, was obtained

through the use of the appropriate calibration curve, Figure 2. The

volume of the toluene used for the extraction was calculated from its

weight and density at the solution temperature.

The weight of BBOT found (jig) = concentration (|_Lg/ml) x volume

of solvent (ml)

2

Total soil retained, p,g/cm = BBOT , tig found

BBOT content x Extraction area

BBOT, ug found

0.033 x 7.917 cm

- BBOT, |ig found x 3.828

3. A Modified Procedure Using Aluminum Alloy Specimens.

A series of experiments was made using uncoated specimens of

aluminum alloy. This material was selected because it presented a
- 6

“

uniform textured surface, and adjacent 4- inch specimens from the same sheet

had a greater probability of being uniform, than porcelain enamel specimens

from the same lot. In addition the material, in 0.064-inch thick sheets,

was easily shearable into I- inch square test pieces which would provide

replicate coupons from a specimen soiled and cleaned in a single operation.

The soil from a l- inch coupon could be rapidly extracted by dropping

the coupon into a known volume of toluene, thus minimizing the possible

errors of the normal extraction procedure. Precise estimations of

coupon area were readily obtained from the specimen weight, density

and thickness.

The pattern for shearing four 1-inch coupons from a 4- inch specimen

is illustrated in Figure 3. The aluminum alloy specimens were cleaned

before testing in the maimer outlined for porcelain enamel specimens

except that a 30-second scrub with a nylon bristle hand brush in a mild

etching cleaner was substituted for the trisodium phosphate scrub.

RESULTS AND DISCUSSION

Seven soiling and cleaning methods were explored in an attempt to

find the most reproducible. These methods, which are outlined in Table 1,

differ in the soiling implement, the grade of cleaning tissues used and

the length of time used in the cleaning process. Methods one through

four were evaluated using similar specimens of a buff colored porcelain

enamel from a single lot. Eight specimens of the porcelain enamel were

tested by each method and individual amounts of retained soil were

recorded. The results obtained when using these four methods are given

in the top part of Table 2. It can be seen that., as the time of the
-7-

cleaning operation was increased from 0.75 to 3.5 minutes, the amount

of retained soil steadily decreased. The results are also characterized

by quite large specimen- to- specimen variability as indicated by the coefficients of variation. This measure of scatter is simply the standard

deviation from the mean value expressed as a percentage of the mean value.

The results by which methods 2, 5, 6 and 7 were compared are given

in Tables 2 and 3. As the cleaning operation was extended from 1.5 to

5.5 minutes in methods 5, 6 and 7, one can see a gradual reduction in

the amount of retained soil, but what was more encouraging, the specimento-specimen variation also decreased materially.

Figure 4 shows the dependance of amount of retained soil on the

cleaning time when methods 5, 6 and 7 were used on aluminum alloy specimens.

In this figure, the average amount of retained soil is represented by

a point on the graph at the appropriate cleaning time. The vertical

bars through each point extend from one standard deviation above to one

standard deviation below each average value of retained soil. Thus the

position of the points and the length of the deviation bars show both

the effectiveness of the cleaning treatment and its variability.

The principle variables involved in the measurement of the fluoresence extracted from replicate pieces were the simplified extraction

procedure and the variability associated with the analytical method.

The variation between specimen averages, on the other hand, must be

associated with the combined errors in the soiling, the cleaning, the

extraction and the analytical determination of fluorescence. The variation among replicate pieces of the same specimen, which might be
- 8

-

referred to as the error of the "method", was small when compared with

the variation between specimens. This suggested that the analytical

method was precise enough to sort out real difference,® from specimen

to specimen of the same composition.

Method 7, together with the method of fluorescence measurements,

was shown to be a procedure capable of determining retained soil on a

series of uniform specimens with a coefficient of variation of 10 percent.

This method was the best of those tried and was selected for a series

of tests on specimens of porcelain enamels and other materials. It was

desired to show the range of values for retained soil that might be

found for candidate surfaces that differed in gloss, acid resistance,

color, material and texture. It was also desired to determine whether

this testing procedure was sufficiently precise to provide significantly

different cleanability values for these surfaces.

The results obtained on the surfaces tested are given in Table 4.

In most cases six specimens of each candidate surface were evaluated

and the average given together with its coefficient of variation.

It can be observed that the average value for the coefficient of

variation was 24 percent when method 7 was applied to porcelain enamel

and other materials. It will be recalled that this method was capable

of yielding a 10 percent coefficient between aluminum alloy specimens.

The somewhat greater variability found when this method was applied to

other surfaces, indicates that the responsibility for the increased

variability must be attributed either to the more complicated extraction

procedure used in the latter case or to real differences in specimen
-9

cleanabilitv within a group of similar surfaces (the same enamel

composition)

The porcelain enamels in Table 4 have been arranged in the order

of decreasing gloss. In general, there appears to be some dependance

of retained soil,£>h gloss. It is probable that the acid resistance of

enamels has little influence on cleanabilitv . This is not surprising

because acid resistance would be expected to depend, to a large extent;

on the composition of the enamel layer. The definability, on the other

hand, might be expected to depend more on surface texture than on

enamel corn-position.

Eiight porcelain enamels tested had values of 45° specular gloss

between 55 and 63 units. If was of interest to determine whether the

average amounts of retained soil found in these tests indicated statistically significant differences in cleanability among these porcelain

enamels. The eight enamels were arranged in the order of their cleanability values as shown in Table 5. Comparisons were made between each

enamel and all of the others, individually. The statistic used to test

1 / the significance of the observed differences was which is defined

in Table 5. It can be seen that no s ighi finance , at the 95 percent

confidence level, could be attached to the small differences found when

seven of the nearest neighbor (in this series) enamels were compared.

In the other 21 comparisons, however, where the differences between

average values were somewhat larger, the differences were found to be

statistically significant at the 95 percent confidence level.
- 10-

The results given in Table 4 suggest the following observations

:

1. The specimen- to- specimen variability in cleanability

values for materials tested to date was not unreasonable in view of

the microgram quantities of retained soil determined.

2. A test for cleanability as outlined in this report should

be based on the average of no less than six specimens.

3. The cleanability test used was sensitive enough to differentiate between many of the glossy porcelain enamels when average values

of retained soil were less than one microgram per square centimeter.

PLANS FOR NEXT REPORT PERIOD

(a) Determinations using method 7 on other surfaces such as polished

plate glass, glazed vitrified china, wall tile, and polyester gel-coats.

(b) The use of image gloss and profilometer traces to describe

surface textures.

(c) Improvement of the extraction method.

(d) A program to show whether correlation can be found between

cleanability estimates by the use of fluorescent soils and other estimates that more closely simulate domestic cleaning procedures.

(e) Determining the soiling and cleaning treatments necessary with

new, less expensive lapping equipment to give results comparable with

those obtained with the equipment illustrated in Figure 1.
- 11=

II. EXPOSURE TEST OF PORCELAIN ENAMELED ALUMINUM

INTRODUCTION

The development of porcelain enamels for aluminum has opened a

whole new field in the porcelain enameling industry. Early exposure

2 / test data— on these enamels have indicated that accelerated exposure

tests designed for porcelain enamels on steel were not completely

reliable indicators of the weatherability of the lower firing enamels

that are applied to aluminum. This is especially true when these

enamels are compared with enamels that are applied to steel. Therefore, early in 1964, the Aluminum Council of the Porcelain Enamel

Institute authorized an exposure test of enamels on aluminum to be conducted jointly by the Porcelain Enamel Institute and the National

Bureau of Standards. These enamels have now been exposed for six months

The specimens exposed at all sites except Los Angeles have been returned

to the Bureau of Standards for inspection. Those exposed at Los Angeles

have not yet been received but they are expected early next quarter.

1. Test Specimens

Sixteen enamels are included in this test. These enamels vary in

gloss, color and thickness as previously reported. If minor variations

in milling and firing for the different fabricators, are taken into

consideration, a total of 51 different enamels are included in this test

In an effort to minimize specimen to specimen variations, each

enamel was applied to a 3 x 5 foot sheet of 0.064-inch 6061 aluminum

alloy. After the sheets had been fired, they were cut into 94 exposure

specimens
-12

2. Exposure Sites

The enamels are exposed on the roofs of Federal Government buildings

in New York City, New York; Los Angele|s, California; and Washington, D.C,

as well as the roof of the Stores Department Building in Montreal, Canada

and a ground site at Kure Beach, North Carolina - 80 feet from the ocean.

The specimens are exposed at 45° and face south at all sites except Kure

Beach where they are exposed, courtesy of the International Nickel

Company; on their exposure racks which are at 30° and face the ocean

at East-Southeast.

RESULTS

1. Cleaning of Specimens

2 3/ In previous exposure tests —a—- the specimens exposed at one of

the sites required scouring before the enamel surface could be examined.

These scouring treatments tended to increase the gloss readings of the

enamels so they were not comparable with enamels exposed at the other

sites. Therefore, in this test, it was decided to scour the specimens

both before and after exposure.

The specimens were cleaned by 1) scouring 30 strokes with a sponge

dampened with a one percent, by weight, solution of trisodium phosphate

and sprinkled with calcium carbonate, 2) rinsing with tap water, 3)

rinsing with distilled water, and finally 4) rinsing with alcohol.

This method of cleaning was satisfactory for the specimens exposed at

all sites except New York City. The specimens exposed for six months

at New York City were covered with a film, approximately 0.03 mils thick,

that was very difficult to remove. The cleaning procedure was altered
- 13-

slight ly to scouring with calcium carbonate on cheesecloth until the

specimens were clean. They were then rinsed as described above.

2, Gloss and Color

The 45° specular gloss of the enamels was measured at four

orientations near the center of the specimen, both before and after

exposure. The gloss is reported as the percentage gloss retained after

exposure

The color of the specimens was measured with a color difference

meter. One of the reference panels was used as the standard in measuring

the color difference. This was done to obtain efficiency with this

type of instrument. The reference standard was, in turn, measured

against calibrated NBS color standards to determine whether the enamels

change color during storage. The color change is reported as color re- 4/ tention which is 100 minus the color difference in NBS units— .

The average percentage gloss retained and color retention for the

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

reference enamels are given in Table 6.

3. Comparison of Exposure Sites

The average values for color retention and percentage gloss retained for all enamels exposed at each site are given in Table 7. A

5/ two-sided sign test— performed on the data indicated a significant

difference between Kure Beach and all other sites for both gloss and

color. There was also a significant difference noted between Washington

and both Montreal and New York for one of the two parameters but not

both. Therefore, these differences were not considered significant at
-14-

this time. It must be noted that six months is a relatively short

exposure time and that the differences between sites will probably be

more pronounced with increased exposure time.

4. Comparison of Enamel Colors

The average color retention and percentage gloss retained for each

of the nine colors included in the test are presented in Table 8. It

is obvious that the red enamels showed the poorest color retention at

all sites. However, all the red enamels failed the 15-second nitric

acid spot test included in the Specification for Porcelain Enamel on

Aluminum for Weather Exposure; PEI:ALS-105. In addition, all the red

enamels failed the cupric sulfate test for color retention which is

included in the Specification for Architectural Porcelain Enamel on

Steel for Exterior Use; PEI: S-100.

There was very little difference between the color stability of

the remaining eight cblors. The slight differences which did occur

were not considered to be significant at this time. Again this may

change with longer exposure time.

5. Comparison of Enamels in the Different Gloss Ranges

The enamels were divided into three gloss ranges; low, medium and

high. The low gloss enamels had an initial 45° specular gloss reading

of less than 35, the medium between 36 and 69, and the high over 70.

Table 9 shows the average gloss and color data for these enamels. The

color retention data are a better criteria for comparing these enamels

because small changes in gloss result in increasingly larger percentage

losses as the initial gloss of the enamel is lowered. When comparing
-17-

were tested with the high-voltage tester. The enamels were arbitrarily

divided into two classes, poor and good, depending on whether the exposed

specimens did or did not rust in six months. The results of the highvoltage probes are presented in Figure 5. Here it can be seen that the

best Reparation occurs at 2 kv. All of the enamels that rusted in

service failed the discharge test at 2 kv. However, 40% of the enamels

that did not rust also failed at this voltage. This high percentage

could be caused by 1) the short exposure time which did not permit the

potentially poor enamels to rust, 2) differences between the storage

specimens and the exposed specimens and 3) lack of correlation between

the test method and actual service data.

2. Relative Severity of Kure Beach-80

The high percentage of good enamels that failed the high-voltage

discharge test at 2 kv led to an investigation of the relative severity

of Kure Beach-80 and other sites. Perhaps specimens which rusted in

six months at Kure Beach-80 wouldn’t rust at all for 15-20 years at any

other exposure site. A review of the literature disclosed an exposure

6 /

test conducted by ASTM” that may be applicable in the present situation.

This work was done to compare the corrosion occurring on both mild steel

and zinc exposed at many different sites. It was found that one-year

exposures of steel were significant to get reproducible results at

rural and industrial sites but specimens exposed at. marine sites had

corrosion occurring at increased rates for the first four years of

exposure. This increased corrosion rate was thought to be caused by

the accumulation of salt deposits on the underside of the specimens.
-18-

However, since the enamels in question had been exposed for only six

months, the one-year data for steel specimens reported in reference 6

were evaluated*. In this evaluation the relative severity of each site

was determined by dividing the average weight loss of the specimens

exposed at the different sites into the average weight loss for the

specimens exposed at Kure Beach-80 * This gave an indication of how

much longer specimens would have to be exposed at other sites before

corrosion comparable to that noted at Kure Beach-80 would occur* These

data are presented in Table 12* The data indicate that specimens that

rusted at Kure Beach-80 in one year would be apt to rust within 5-8

years at many marine or industrial sites® This is, indeed, a very short

time for any architectural porcelain enamel installation to last. Thus

the rusting of 257* of the nature-tone enamels, which have had excellent

public acceptance, in six months exposure at Kure Beach-80 is a problem

that cannot be neglected® It appears reasonable that losses encountered

before installation by testing these enamels at 2 kv would be small

when compared with the losses resulting from a bad public image when

these enamels rust within five to eight years after installation.

3. High-Voltage Test Equipment

There are two basic types of high-voltage test equipment on the

market: AC and DC® The test equipment used in this work has been one

with a variable output of 100 to 5000 DC volts® AC equipment is used

to test glass lined chemical tanks® However it must be noted that AC

and DC volts are not the same® Miller—^has stated that a conversion

factor of 1.7 for AC to DC is commonly agreed on. This means that
-19=

1700 volts DC are equal to 1000 volts AC. This is very important to

remember if one is performing tests with AC instruments instead of DC.

Miller also states that the output of DC equipment is not accurate below

10-207= of its maximum output.

PLANS FOR NEXT REPORT ffEROID

During the next report period it is planned to test enamels of

various thicknesses to determine the effect of thickness, on the highvoltage discharge testing. It is also planned to test some appliance

enamels
20 -

REFERENCES

1. W. J. Youden, Statistical Methods for Chemists, John Wiley & Sons,

New York ( 195 1)

.

2. M, A, Rushmer and M. D Burdick, Weather Resistance of Porcelain

Enamels Effect of Exposure Site and Other Variables after Seven

Years, NBS Building Science Series No . 4 , To be published in 1966.

3. D. G. Moore and W 6 N. Harrison, Fifteen-year Exposure Test of

Porcelain Enamels, National Bureau of Standards Building Materials

and Structures Report 148, June 1957.

4. Ro S „ Hunter, Photoelectric Color-Difference Meter, J „ Optical

Society of America. 38, 661 (1948).

5. M. G. Natrella, Experimental Statistics, NBS Handbook 91 (1963).

6 „ Report of Subgroup of Subcommittee VII, on Corrosiveness of Various

Atmospheric Test Sites as Measured by Specimens of Steel and Zinc,

Proceedings American Society for Testing and Materials, 59, 183-

201 (1959).

7. Harold W. Miller, Nondestructive High Potential Testing, Hayden

Book Company, New York.
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X

X

CO

CJ 0) X Jt! a o

S3

X

Xo

03 cO o x X C d o

CO

N

X

X

O

X

CO

H

C

03 O- 03

03

g

X

d 03 X

X

O MD X -o X 3 X X X S3 X X X x 3 X o h e

44 CO • n 0) •H CL co 00 CL X X X CL X X e 03 S3 e3 S3 -u 0 C

CM 03

d 03 •H

X 3

cn

X

X 0 X 03 s X

X CJ X X 03 X

0) S3 co

X co

X

X

X o X 03 co c0 co 03 01 X S3 CJ c3 X X X X X U X X d 03 • 50 CL o X f-H X S3 > co

S3 4-1 CL

O 03 co

X

X CLX co o X co

O

X cj

d o 0) CJ 03

0)

d

d

X

Xd r—

.Ft co

X 0) •H o S3 •H

cO

X 0303 S3

CO 3-1 03

co

X tn

O

W o X

po iH

H CO *H 4-J

X

X CL

O & 01 o B • • CO CO X 0) x y x> cd CJ 0) X 03 03 d 0) ^ d X d x •H *H °H •H o

03X rH rH QJ 1 X 3

CJ a- in

a

x

X

X

X 44 P-

® CL o CO

X 03 O cd •h S3 X rH X a X 8 rH

60

w >> CO CN S3

X

X rH Cd rH

X

X IH. r-l ^ pH pH id

d co O S3

X

N

O

03

X

X

t>N

X

X

OO 03

X

X S £L o 03 03 O & cd

•iH

X

B rHB

X 03 • X X S3 03 •X 60 CO X CO 0) 60 X d

CO °r4 «6

d S3

X

d

X co o 03 o 3 Eh •H Dt co CL & to d X & rH •X rH S3 X X o rH •H X X • 03 03 o S3 o o O d |H X 60 X co X co •H CJ S) d 7—l O rH X •H •H X 03 03 03 CO 03 03 a o X X X p X CL •H CO < Eh Eh Ex B Eh O Dt

'di ^1 4 | X|
Table 2.

Average

Coef. of

Variat ion

4" x 4"

Specimen

No.

A

B

C

D

Comparison of Soiling and Cleaning Methods by Fluorometric

Analyses of Retained Soil.

Specimens of BUFF Porcelain Enamel

Acid Resistance HA

,! - Gloss 55 Units

Method 1 Method 2 Method 3 Method 4

pg/cm2 pg/ cm

4 pg/ cm

2 pg/cm2

1.97 1.46 1.46 , 6.83^/

0.78

3.09 1.63 .54

1.82 1.40 0.74 .62

1.25 1.61 .62 .81

3.69 1.31 1.65 .90

2.80 1.72 1,64 .99

2.37 1.65 1.84 1.00

1.78 1.80 1.35 • 0.94

2.35 1.57 1.33 0.82

34% 11% 35% 20%

Specimens of 6061 Aluminum Alloy Mill Finish

Soiling and Cleaning Method 2

Soil Retained on 1" x 1" Replicate Coeficient of

Pieces of the Same Specimen Variation

(Between Replicates)

pg/cm2 Average Percent

7.80 6.51 6.69 6.31 6.83 9.7

8,18 7.94 8.17 8,60 8.22 3.4

5.90 6.19 6.29 6.13 6.13 2.7

6 .66 6.07 6.62 6.42 ' 6 .44 4.3

Average 6.90 5.0

Coeficient of Variation

(Between Specimens) 13%

a / Omitted from average
4" x

Specii

No

14

9

78

10

5

6

2 11

12

13

14

15

16

17

18

19

Comparison of Soiling and Cleaning Methods of Specimens of 6061 Aluminum Alloy by Fluorometric Analyses of Retained Soil.

Soil Retained on 1 Pieces of the Same

2

|ig/ cm

Method 5

3.72 3.05 3.24

4.26 4.14 4.26

2.17 2.18 2.24

2.01 1.88

2.68 2.61

3.40 3.27

Average

Coeficient of

Variat ion

(Between Replicates)

Average Percent

3.33 10.1

4.22 1.6

2.20 1.7

1.94 4.8

2.64 1.9

3.24 2.8

2.94 3.8

x 1 M Replicate

Specimen

Coeficient of Variation

(Between Specimens) 297D Method 6

2.04 1.75 2.04 1.94 8.6

1.83 1.53 1.51 1.62 11.0

2.12 2.24 2.76 2.37 14.3

1.72 1.65 1.69

' 2.9

1.81 1.74 1.78 2 .9 1.52 1.42 1.47 5.7

Average 1.81 7.5

Coeficient of Variation

(Between Specimens)

Method 7

1.40 1.23

1.44 1.45

1.29 1.17

1.43 1 o47

1.63 1.64

1.45 1.37

17%

1.32 9.1

1.44 0.1

1.23 6.9

1.45 2.0

1.64 0.4

1.41 4.0

1.42 3.8 Average

Coeficient of Variation

(Between Specimens) 9.8%
Table 4. The Estimation of the Cleanability of Porcelain Enamels

and Other Materials .£/

Material Charac- 45® Specu- Acid Total Soijl,

Retained—

pg/cm^

Coefficient

teristic lar Gloss

Value

Rating of

Variation

Percent

Porcelain

Ename

1

White 63 A 0.18 24

11 1AA 62 AA .33 24

18 FOR 61 B .78 11

18 Brown 60 AA .24 23

11 IRA 60 A .41 17

81 OAA 58 AA .53 ,

. 15—7 24

18 Buff 55 A 15

18 CO 55 C .30 26

" (matte) 4F 16 D 1.72 , 7.72^

25

68 8 1 2F 9 B 19

11 11 FI 8 A 8.76 30

18 If 3F 6 C 1.24 41

Po lyester

Gel Coat DF 56 — 1.82 14

Aluminum

Alloy 6061 1.42 10

a/ These estimates of cleanability were made employing Method 7, outlined

in Table 1. Low values of retained soil indicate good cleanability;

larger values are associated with poorer cleanability.

b / The value given is the average for six specimens unless otherwise noted.

c/ Average for 5 specimens,

d/ Average for 4 specimens.
Table 5. Results of Tests for Significance of the Differences in

Cleanability Among the Glossy Porcelain Enamels on Steel.—

Buff White Brown CO IAA IRA OAA FOR

0.152 0.185 0.241 0.295 0.329 0.412 0.533 0.780

FOR 0.780 s s s s s s s --

OAA .533 s s s s s ns --

IRA .412 s s s s ns --

IAA .329 s s ns ns --

CO .295 s s ns --

Brown .241 s ns --

White .185 ns --

Buff .152 --

An "s" in the body of the table indicates that the cleanability values

for the enamels at the head of that row and column were found to differ

significantly at the 95% confidence level.

An "ns" in the table indicates that no significance was found by a "t"

test for that pair of enamels at the 95% level of confidence.

a / The statistic used to test the significance of differences between

averages was:

x - *y r~~nm

t = _Sp

*y

| _n + m

where

x = mean value for n determinations in one set.

y

= mean value for m determinations in the other set.

Sp = standard deviation pooled from both sets.
TABLE 6 SUMMARY OF SIX MONTHS EXPOSURE DATA FOP. PORCELAIN ENAMELS ON ALUMINUM

ACID Enamel KURE BEACH WASHINGTON MONTREAL NEW YORK STORAGE VISUAL SOLUBILITY Gloss Color Gloss Color Gloss Color Glos s Color Gloss Color Color mg/in

AA-A 85.5 99.4 93.2 99.5 93.8 99.5 98. 3 99.4 98.8 99.9 White 5.5

AA-B 94.0 99. 3 92.7 99.5 98.6 99.4 94.5 99. 7 99-2 99.7 White 5.9

AA-G 90.7 99.0 90.7 98.8 92.0 98.9 92.3 99.2 99.1 99.9 White 5.0

AA-D 76.0 98.3 94

.

6 97.8 100.0 97 .

8

101.1 97.9 99.2 99 .

&

White 12.

7

AB-A 81.2 98,8 62.8 98.8 83.9 98. 7 95.9 98.1 99.6 99.9 White 7.2

AB-C 79.6 99.6 81.0 99. 5 82.7 99.4 83.9 99.2 98.

1

99.8 White 4.9

AB-D 75.3 98.5 93.3 98.9 80.0 98.9 100.5 98.3 99.2 99.9 White 7.9

AC -A 90.2 99.4 93.0 99.3 98.6 98.6 96. 3 99.3 99.0 99.4 White 6.4

AC-B 85.8 98.7 92.8 99.1 101.

3

99.0 103.4 99.0 99.3 99.8 White 11.3

AC-C 90.6 98. 3 93-7 98.6 98.3 98.9 99.0 98.7 99.8 99.7 White 9.9

AD-A 87.6 98.9 91.7 99-4 90.3 99.5 100.9 99.2 99.6 99.7 White 6.2

AD-B 89 .O 99.4 89.8 99.6 90.5 99.5 97.4 99.1 99.6 99.8 White 6.7

AD-C 82.8 98.1 90.9 99.0 88.6 99.1 105.3 98.1 98.8 99.7 White 7.1

AD-D 87.5 98.1 98.0 96.9 87.7 98.8 104.7 98.

1

99 .

6

99.7 White 12.4

AS -A 76.4 99.

1

81 . 3 98.6 82.

1

99.8 82.3 99.8 97.8 99.6 Black 6 . 5 AE-B 65.1 98.6 86.5 99.8 88.8 99.5 84.6 99.6 98.8 99.8 Black • 10.1

AE-C 72.6 98.9 89.4 99.6 91.9 99.5 86.7 99-6 98,4 100.0 Black 12.1

AE-D 71.1 98.6 82.2 98.0 87.4 99.7 83.3 98.9 98.6 99.5 Black 15.5

AF-A 65.6 98.4 69.5 96.0 90.4 99.3 82.

1

98. 5 99.0 99.7 B lack 14.2

AF-B 69.7 99. l 115.0 97.9 95.6 99.4 88.3 99.4 98.5 99.8 Black 9.0

AF-C 72.2 98.4 84.5 98.8 88.2 99.8 84.4 99. 3 98.8 99.6 Black 10.1

AG-B 82.0 97.6 100.5 98.6 81.3 98.9 76.2 98.4 98.6 99.7 Black 12.

5

AS-B 46.9 98.2 105.7 99.4 31.8 99.5 35.9 98.3 96.2 99.4 Black 7.5 AH -A 90.8 97.5 95.8 98.1 97.8 97.5 118 . 3 97.6 100.3 99.3 Red 8.1

AH-B 64.3 93.0 72.3 94.6 75.4 95.2 81.7 96 .

6

100.1 99.7 Red 8.6

AH-C 73.9 90.

1

70.8 91.9 77.3 92.8 75.5 91.5 100.1 99-4 Red 6.5

AH-D 59.7 83.6 74.7 88.9 82.8 89.7 79.0 95.2 99.6 99.6 Red 10. 5 AO -A 76.6 95-^ 82.1 99.1 83.8 99.3 80.2 99-7 99.5 99.7 Dk»Green 19.

9

AO-B 72.5 99.5 84.0 99.5 83.4 99-7 83 .O 99.1 99.2 99.7 Dk .Green 10.1

AO-D 74 .

1

97.8 83.8 98.5 87.8 99.4 81.0 99.4 98.9 99.7 Dk.Green 17.0

AP-A 82.2 98.7 95.5 99.4 92.1 99.5 102.3 99.4 99.2 99.8 Lt .Green 12.3

AP-B 75.5 99.4 82.9 99.4 78.6 99-6 86.3 99.6 98.7 99.8 Lt .Green 6.4

AP-C 73.9 99.5 85.7 99.0 76.4 99.5 85.8 99.6 98.2 99 .

8

It .Green 6.2

AP-D 87.5 99.1 93.9 99.0 91.7 99.3 95. a 99.5 98.

1

99.8 Lt .Green 10.0

AR-A 47.0 99.6 111.8 99-5 62.4 99.6 54.2 99. 3 94.5 99.7 Lt .Green 4.4

AR-B 0.0 99.4 82.5 99.6 4.4 99-7 0.0 98.8 100.0 99.8 Lt .Green 5-5 AR-e 0.0 99.4 85.7 99.6 0.0 99.7 0.0 98.8 100.5 99.7 Lt .Green 8.1

AS -A 78.2 98.7 90.2 99.4 91.2 99.5 91. 7 99.

98.7 99.9 Gray 13.4

AS-B 83.7 98.9 83.0 99.3 83.0 99.4 85.0 99.2 99.1 99.6 Gray 7.4

AS-C 92.5 99.8 91.8 99.6 91.7 99.8 90.4 99.6 99.0 99.1 Gray 5.4

AT-A 75.2 99.0 83.8 98.9 68.3 99.1 80.4 98.9 98.8 99.8 Blue 6.2

AT-B 79.8 98.6 93.8 98.9 91.0 99.3 91.5 98.6 99.4 99.9 Blue 1.0

AT-C 81.5 98.7 78.8 97.1 80.9 99.3 83.3 99.2 98.8 99.8 Blue 6.1

AU-A 89.1 99.3 84.3 99.7 81.2 99.8 88.3 99.7 99.1 99.6 Brown 5.3

AU-B 75.7 99.2 92.4 99.6 79.9 99-8 98.0 99.5 98.2 99.8 Brown 7.5

AU-C 87.4 99.8 94.5 99.5 91.5 99.8 95.1 99.6 98.6 99 .

8

Brown 7-6

AW -A 81.4 99.2 82.7 99.4 85.7 99.6 86.2 99.5 98.8 99.9 Yellow 7.8

AW-B 78.8 99.3 93.3 99.2 94.2 99.2 95.6 99.3 98.5 99.8 Yellow 8.7

.AW -C 72.1 98.9 84.6 99.4 90.3 99.91.4 99.4 99-7 99.9 • Yellow 18.6

AZ-A 100.9 97.7 . 93.5 99.3 102.4 99.1 103.4 99.2 100.7 99.9 White 9.5

AZ-B 94.2 99.1 90.6 99.0 93.9 99.3 90.9 99.2 100.0 99.1 White 5.2

Average 75.8 98.2 87.3 98. 5 81.7 98.9 85.7 98.8 99.0 99.1
Table 7. Average Gloss and Color Retantion of Porcelain Enameled

Aluminum at the Different Exposure Sites

Exposure Site Color Retention Gloss Retain

(Percent)

Kure Beach-80 98.2 75.8

Washington 98.5 87.3

Montreal 98.9 81.7

New York 98.8 85.7

Storage 99.7 99.0
Table

8.

Average

Gloss

and

Color

Values

for

the

Different

Colors

of

Porcelain

Enameled

Aluminum

Exposed

for

Six

Months • o o co o ON N0 • • • • • » 0 • • o o on ON 00 ON On 00 CO co u

C/3 orH on O' On ON O' O' on O'. • VO r—1 o cm pH o vO

CO * • • • • • ® • * • CO m 00 00 I—1

rH ON o m z 00 00 O' r~- 00 CN 00 NO on

mwo • f—1 4_l CO o I'- O' o r*H NO O' CM o c ® « • • « o CO o CN m o 00 n- s 00 00 Oh 00 00 ON 00 m 00 • m n£> in CO On cn rH

Cfi « « • « • • ® • « <d 00 m cm o CO NO 00 pH o 00 O' O'. 00 00 00 On On • CM 00 on pH 00 cn rH W • • • • « * • « • • CSI CO NO on -4- CM

r^. n- 00 'D co in 00 9 in 00 00 O' r^ 00 O 9 « • « • - * a • • U O' O' O' ON Oh O' ON Oh

C/3 O' O' O' Oh * ON O' Oh O' Oh « CM on On pH NO cn NO

>-< • « in 00 00 on on ON O' on O'

on ON ON O' O' O' O' On O'

l-i o

rH • o +J 00 CM

O inm 'O n£> 00 o e o O © • • • 9 • • o cn ON on on O' O' O' ON O' S on on O' O' O' O' O' ON O' « 4= cn O' in o cn NO

CO

cd cn 00 00 00 O' on O' ON O' 3 on On O' ON O' O' on O' O' • pH 00 03 in No pH rH cn

PQ 9 9 o « • « » • © • pH 00 00 00 ON Oh on Oh

Oh On a\ O' Oh O' Oh CN Oh

rH &

0) J-l 03 s o •U c c P o 03 •U u 4d 0) pH >N xz 03

c3 r-l T3 3 •H cd 0) rH sd

to 03 o c O 0) pH X pH OS u 03 •H U M w o eS PQ !3 CQ a o O hJ o PQ
Table 9. Average Color Retention and Percentage Gloss Retained for

Different Gloss Ranges of Porcelain Enameled Aluminum

Exposed for Six Months

Color Retention

Gloss

Range

Kure Beach Washington Montreal New York Storage

Low 98.8 99.2 99.4' 98.7 99.7

Medium* 99.0 99.0 99.5 99.2 99.8

High* 98.6 98.9 99.2 99.2 99.8

Percent Gloss Retained

Gloss

Range

Kure Beach Washington Montreal New York Storage

Low 46 .6 94.7 46.9 49.6 98.3

Medium* 82.1 90.1 87.1 92.9 98.9

High* 78.4 85.4 90.4 88.8 99.6

*The averages for the medium and high gloss enamels were calculated

omitting the red enamels since they showed such great color changes.
Table 10. Average Color Retention and Percentage/ Gloss Retained for

One and Two Coat Systems of Porcelain Enameled Aluminum

Exposed for Six Months

Color Retention

Number

of Coats

Kure Beach Washington Montreal New York Storage

One* 98.5 98.7 99.3 99.1 99.7

Two; 99.1 99.2 99.4 99.2 99.8

Percentage Gloss Retained

Number

of Coats

Kure Beach Washington Montreal New York Storage

One* 76.8 90 J 86.7 87.1 98.9

Two 75.7 88.7 80.8 84.3 98.9

* The red enamels were omitted when the average values for the one

-oat systems were calculated because they showed such great color

changes

.
Table 11. Comparison of Porcelain Enamels on Aluminum with Other

Porcelain Enamels Exposed for Six Months at Kure Beach-80

Exposure Test Gloss Color Number

Present Aluminum Test 75.8 98.2 51

Aluminum Enamels in

1956 Test

80.5 98.5 10

AR Enamels on Steel,

1956 Test

77.8 98.4 25
Table 12® Comparison of the Corrosion of Mild Steel Exposed at

Eleven Sites for One Year

Exposure Site 3.

1

Grams Weight Lost- Severity

(KB-80/Exp

Marine Sites

Kure Beach-80,

North Carolina

90.2 1.0

Daytona, Florida 48.5 1.9

Pt . Reyes,

California

12.2 ft 00

Kure Beach-800

North Carolina

12.0 7.5

Industrial Sites

New York City,

New York - Fall Installation

40.5 2.2

Kearny, New Jersey 22,2 4.1

New York City,

New York - Spring Installation

21.1 4.3

Middletown, Ohio 8.4 10.7

Rural Sites

South Bend,

Pennsylvania

10.5 8.6

State College,

Pennsylvania

6.8 13.3

Perrine, Florida 5.8 15.6

a / See reference 6