ing powder that has been applied to a brush, sponge, or cloth.

Another method which was investigated was the Schiefer Abrasion-Testing Machine, originally designed for testing textiles [9]. In modifying the machine for testing floor covering [10], a brass cup was added to hold the specimen and a nylon brush and alkaline soap solution were used to provide the abrasion. Both cup and brush were rotated at 250 rpm with axes of rotation one inch apart. In the present investigation, trials were made using this modification on specimens of por celain-enameled steel, circularly cut to fit the brass cup. A slurry of Ajax brand scouring powder and water was used as the abradant. The same nylon brush used to test floor covering was employed with four pounds of force being applied to the brush. After 10,000 revolutions, the center region of the specimen was worn, rather than the outer portion, although the brush covered the entire specimen. Apparently only the "high spots" on the specimens were affected by the treatment. In an attempt to eliminate this difficulty, the bristles were removed from a nylon brush and replaced with sponge rubber. This pad was then used with Ajax slurry to abrade a second porcelain-enameled steel specimen. Again the specimen was worn near the center but not on the outer portion. In other tests, a cellulose sponge with Ajax slurry showed practically no effect on a specimen after 10,000 cycles. Also, Pellon non-woven cloth was cemented onto the nylon brush holder and another porcelainenameled-steel specimen abraded with Ajax for 10,000 cycles at a 4-lb force. Although this treatment resulted in a more uniform abrasion, the surface being dull over most of the test area, the abrasion was still not sufficiently uniform, nor was it measurable with the depth gage.

It was apparent that a good deal of additional work is necessary to determine whether the Schiefer machine can be adapted to testing sanitary ware. Its use in testing of sanitary ware is time-consuming largely because of the difficulty in preparing the circular specimens required in present applications of the machine.

TABLE 2.10-2.

The one test method in current use for sanitary fixtures that apparently simulates actual cleaning practices for sanitary ware is that specified in section 6.5 of the proposed revision of CS 221-59 [1]. The abrasion requirement in this proposed standard for FRPE fixtures is that the coating shall not wear through to the backing material after 10,000 wear cycles in the Gardner Heavy Duty Wear Tester, modified as described in the proposed revision. This test, with minor modifications, is the one recommended as a performance test for abrasion resistance based on the present study. Results of tests using this method are given in section 2.10d (2) of this report.

Other tests that have been used for abrasionresistance testing of sheet or plate materials were reviewed but no tests were made [11, 12, 13, 14]. It was obvious that none of these tests closely simulated the action of cleaning a fixture with scouring powder.

(2) Test Data

Table 2.10-2 compares the results obtained when sanitary ware materials were tested in accordance with (a) section 6.5 of the proposed revision of CS 221-59 and (b) the method specified in section 2.10b herein. The agreement in the results between the two test procedures is good. This might be expected, since the only differences between the two tests is in the abrasive slurry. The data indicate that the "standard abrasive slurry" specified in section 2.10b (2) gives approximately the same abrasive action as does the Ajax scouring powder specified in the proposed revision of CS 221–59.

Coating-thickness contours across the surfaces of an FRPE and a porcelain-enameled-steel specimen after 10,000 wear cycles (20,000 strokes) with "standard abrasive" are shown in figure 2.10-2. Results with a porcelain-enameled cast-iron specimen, although not shown, were similar to those for porcelain-enameled steel. The loss in thickness for porcelain-enameled surfaces after the 10,000 cycle treatment was approximately 0.0002 in, although accurate measurements could not be made owing to the uneveness of the surfaces.

(3) Rationale for Test Selection

The reason for recommending the abrasion test specified in section 2.10b are as follows:

1. The recommended test method simulates the abrasive wear that occurs in service through the common practice of cleaning sanitary fixtures with abrasive scouring powders. Another potentially applicable method (the Schiefer test) requires further development work for application to sanitary fixture materials.

2. The basic equipment necessary to make the test is available commercially and the necessary modifications can be made in any well-equipped laboratory. A similar test using this equipment is already in use for FRPE fixtures; thus laboratories are familiar with the equipment and its use.

3. The differences in abrasion resistance between the various materials currently used for sanitary ware as evaluated by the recommended procedure appear to be of the same order of magnitude as indicated both by qualitative handrubbing tests and field observations.

d. Comments on Performance Requirements (1) Suggested Format for a Performance Level

Wear-through to the backing material as evidenced by a change in color and texture shall not occur on any of the three specimens. Also, in those cases where no wear-through occurs, the average wear depth for the three specimens shall not exceed in.

(2) Rationale for Suggested Format

It was not possible in the present study to establish a relation between the number of cycles in the wear tester and the abrasive wear in service. To

suitably investigate a relation of this type would require an expensive and time-consuming survey of both porcelain-enameled and FRPE fixtures. Since both time and budget were limited, such a survey could not be made during the contract year. In attempting to set a realistic wear depth requirement the following factors need to be considered: 1. It seems to be the consensus of the FRPE sanitary ware industry that gel-coat thickness should be greater than 0.010 in, both from the manufacturing and end-use standpoints. Presumably this is a sound consensus based on industry experience accumulated over the past 5 years. It should be pointed out that a polyester gel-coat applied at a thickness of greater than 0.010 in would not wear through to the backing material in 10,000 cycles.

2. The introduction of new materials having an abrasion resistance appreciably lower than the current gel-coats would be prevented if the average wear depth was set at 0.010 in. This might be desirable since until such time as it can be demonstrated that household scouring powders will not be used on plastic fixtures, a high performance level for abrasion resistance would seem to be almost mandatory.

3. Wear-through to the base material in less than 10,000 cycles should not be permitted, since exposure of the base material would be highly undesirable from the standpoint of sanitation and overall appearance.

4. Selection of 10,000 cycles for the test duration is based on the requirements specified in the proposed revision of CS 221-59. A shorter testing period would not seem advisable until such time as the relation between wear rates in the test and wear rate in service can be investigated adequately.

2.11. Cleanability and Soilability (M203A)

a. Purpose and Scope

The purpose of this test is to evaluate both the aesthetic soilability and cleanability of sanitary plumbing fixtures. Soilability is defined as the degree to which a surface accumulates and retains the kinds of soiling materials associated with sanitary plumbing fixtures. Cleanability refers to the ease of removal of these same soiling agents. Retention and removal of bacteria are not included in the scope. The discussion of this test is related specifically to bathtubs and shower receptors although it has some applicability to lavatories, sinks, and water closets.

b. Selection of Test Method

A specific test method is not recommended. An acceptable test procedure for soilability should be comprised of two major elements: (1) a reproducible soiling agent that suitably simulates actual soiling materials in the bathtub with respect to chemical composition, color, adherence properties, hardening and drying properties, etc., and (2) a suitable method for evaluating the accumulated soiling material in terms of some physical property such as weight, volume, reflectance, etc.

An acceptable test procedure for cleanability should be comprised of three major elements: (1) a soiling agent that suitably simulates actual soiling materials in a bathtub (see above), (2) a scrubbing procedure that suitably simulates techniques, and materials used under actual service conditions, and (3) a suitable method for evaluating the aesthetic cleanliness of the surface in terms of some physical property such as reflectance or retention of some tracer material, the presence of which can be detected in quantitative fashion.

A number of existing methods, laboratory investigation of some of these methods, and development work on new standard soiling agents and measurement techniques are described. Additional laboratory work is summarized that is needed to develop a suitable standard soiling agent, scrubbing procedures, and procedures for evaluation of accumulation of soil and cleanliness of the surfaces of sanitary plumbing fixtures.

c. Discussion of Existing Test Methods

(1) Soilability

Laboratory investigation indicated that the soiling agents developed for published test procedures did not suitably simulate the soiling materials in a bathtub. While there is no scientific evidence to support it, the common idea is that the ring in the bathtub is the most difficult cleaning problem. No publications were discovered that described attempts to study or duplicate "bathtub ring."

A number of different test methods have been used to evaluate the cleanability of surfaces. These are described briefly together with a discussion of their relevance to performance tests for sanitary plumbing fixtures.

(i) Cleanability Test for Fiber-Glass-Reinforced Polyester Bathtubs [1]

The soiling agent used in this test is a "standard dirt" formulated of specified percentages of carbon black, magnetic iron oxide, calcium stearate, motor oil, a wetting agent, and water.

In section 4.4.1 of the proposed revision of CS 221-59 [1], a test method involving the use of the "standard dirt" for detection of voids in the surface is described. Section 6.5 describes the use of the test method as a criterion or measure of cleanability after a 10,000 cycle abrasion treatment of the surface. In testing for cleanability as in section 4.4.1, surfaces to be evaluated are first conditioned by hand scrubbing with wet sponge and scouring powder. About 5 g of "standard dirt" per 16 in2 of surface is then rubbed into the surface with a dampened chamois, using heavy thumb pressure. The dirt is allowed to dry for at least 1 hour and then washed with a clean, dampened chamois and liquid detergent before visual inspection of the surface for dirt retention.

In evaluating abraded surfaces, as prescribed in section 6.5, 10 g of the "standard dirt" are applied to the abraded specimens and rubbed into the surfaces with a dampened chamois, using heavy thumb pressure. After the dirt has dried for at least one hour, the specimens are washed with a liquid household detergent cleanser for about 50 cycles or until no more dirt appears to be removed. Evaluation of the dirt remaining after this clean

ing treatment is accomplished by comparing the white-light reflectance before the dirt is applied with that after the dirt is removed by the specified cleaning treatment. Since this test is already in use for sanitary ware materials, data were obtained in the present investigation following the procedures in the proposed revision of CS 221-59 and also using a modified procedure. The results are given in section 2.11d.

The "standard dirt" in the proposed revision of CS 221-59 is not recommended, principally because of its ease of removal. The findings on this characteristic will be discussed further in section 2.11d herein. As discussed in section 2.11e, it would be desirable to use a more representative, standard soiling agent in both the soilability and the cleanability tests.

(ii) Pencil Test

In the field measurements described in Appendix A, marks made with a 3B drawing pencil were used as a "standard soiling agent" on fixtures of various materials. Cleanability was categorized by ease of removal of these marks using a dry cloth, a damp cloth, a damp cloth with soap, or a damp cloth with household cleaner. While this simple test provides a four-step rating or classification of cleanability, the pencil marks cannot be said to simulate agents in a bathtub in service.

(iii) Washability Tests for Paints

1. A washability test for painted surfaces is prescribed in a Federal Specification [16]. A soiling medium of raw umber, petrolatum, and mineral spirits is applied to the panel with a doctor blade. The coating is dried for 12 hr at 105-110 °C and then cooled. The panel is then tested in a windshield-wiper type of washability apparatus with wet sponge and abrasive soap for 35 cycles (70 strokes). The "apparent daylight reflectance" and 60° specular gloss are determined before and after this treatment.

In considering the suitability of this test for sanitary plumbing fixtures, it should be noted that the soiling medium specified is unlike that encountered in sanitary plumbing fixtures. The use of a liquid detergent for cleaning, rather than an abrasive soap, should be explored since the abrasive soap might cause a change in the surface during

the test.

2. The effectiveness of cleaning agents for painted surfaces was investigated by Wesley E. Shelberg, James L. Mackin, and Ross K. Fuller [17].

The specimens were soiled with "synthetic dirt," formulated to resemble urban and shipboard dirts. The formulation for urban dirt was based on previous chemical and physical analyses of street sweepings from six large eastern U.S. cities, that passed a No. 200 sieve. The following formulation was used to represent urban dirt:

This formulation for a soiling agent probably merits investigation since it includes some of the materials likely to be found in soils on sanitary plumbing fixtures. However, some of the elements of human soiling materials, such as body oils and skin particles, are not present.

(iv) Tests for Bacterial Cleanability [18]

Glass, china, stainless steel, and aluminum plates were seeded with bacteria tagged with radioactive phosphorus, P32. The dishes were washed under various conditions in a commercial dishwasher and radioactive counts performed on the dishes. The above test is not considered applicable to sanitary plumbing fixtures since it is concerned with bacterial cleanability whereas the present study is concerned with evaluating aesthetic cleanability.

(v) Washability of Dinnerware

1. The National Sanitation Foundation at the School of Public Health, University of Michigan, has developed a Use and Wear Machine for simulating use and wear on materials and finishes for chinaware, as mentioned in Western Plumbing Official for May-June 1964. One method for measuring the effectiveness of cleaning procedures is the "salt-shaker" test, described by E. H. Armbruster and G. M. Ridenour [19]. A mixture of 85 percent talc and 15 percent Safranine-O dye is dusted on the surface and rinsed with water. Residual red dye is an indication of remaining fatty oil or grease, protein, and starch.

This is a simple method but not quantitative and applies more to food soil than to the soils likely to be deposited on sanitary plumbing fixtures in bathrooms.

2. Louis E. Wells, Jr. [20] described a method for evaluating liquid detergents using soiled dinner plates and a weighted brush, operated by hand. This might be a good method for preliminary testing but a machine-operated brush would give a more uniform and reproducible cleaning action.

d. Laboratory Studies of Soilability and Cleanability

Laboratory studies of cleanability of bathtubs were made in the present investigation on specimens abraded by the Gardner Heavy Duty Wear Tester using two different abrasive slurries. One slurry was the mixture of 50 percent commercial Ajax cleanser and 50 percent water by weight specified in the proposed revision of CS 221-59. The other slurry was prepared at the National Bureau of Standards using nonproprietary materials as described in section 2.10 on Abrasion Resistance herein. The soiling medium used on the abraded specimens was the "standard dirt" of the following composition, specified in the proposed revision of CS 221-59:

Each value is the average of values for three specimens.

b After soiling with "Standard Dirt" and cleaning with liquid detergent. Measurements by Gardner Color-Difference Meter according to the procedure of ASTM D 1365-60T [38].

• Flat specimens supplied by the manufacturer.

d Specimens cut from bathtub.

Mr. Clean was used for the cleanabilty test.

NBS nonproprietary detergent used for cleanability test.

One of the specimens wore through the gel-coat.

After cleaning with abrasive slurry, Rd increased 4.4 percent.
After cleaning with abrasive slurry, Rd decreased 4.2 percent.

The losses in white-light reflectance, shown in table 2.11-1 for the porcelain-enameled specimens, were largely independent of the abrasive slurries and detergents used. The measurements were made with the Gardner Color-Difference Meter as specified in the proposed revision of CS 221-59, according to the procedure of ASTM D 1365–60T [38].

Some of the abraded specimens were coated with "standard dirt," the excess wiped off with paper wiping tissue and the specimens examined with a linear-traverse microscope. An FRPE specimen abraded by the Gardner Wear Tester showed numerous long scratches in the direction of wear pattern, with no pits. Porcelain-enameled cast-iron and steel specimens, abraded in like manner, showed very few pits on the cast-iron and about