76 pits per linear inch on the steel specimen. Specimens abraded as by ASTM C 448-61 [8] method showed many pits. The entire surface of the FRPE specimen was pitted with little or no space between pits. The porcelain-enameled cast-iron specimen had 357 píts per linear inch, while the steel specimen had 378 per linear inch. From these observations and the foregoing data in table 2.11-1, it appears that deep scratches may affect cleanability much more than do pits.

Limited laboratory studies were made on soiling media. The studies made on cleanability showed that it was not necessary to use scouring powder to remove the "standard dirt" specified in the proposed revision of CS 221-59, unless the surface was badly worn. This was true even when the standard dirt was allowed to dry for 24 hours before removal.

Common experience with bathtubs indicates that "bathtub ring" adheres rather tenaciously to enameled surfaces if allowed to dry overnight. Many brands of toilet soap will also stick tightly to an enameled surface if allowed to dry in contact with the surface. The field survey of installations of FRPE fixtures revealed that most housewives used scouring powder for cleaning their bathtubs. Comparison of these observations with the laboratory experience indicated that the standard dirt specified in the proposed revision of CS 221-59 was more easily removed than actual bathtub soil. In an attempt to develop a soiling medium more like that encountered in bathtubs, "synthetic bathtub ring" was produced on a number of flat specimens of sanitary ware in the stainless-steel tank used for the Water-Resistance Test, section 6.1 of the proposed revision of CS 221-59.

A soiling medium was first formulated from the following ingredients:

The stainless-steel tank was filled with distilled water and solutions of calcium and magnesium chlorides and sodium bicarbonate added to produce hardness equivalent to 300 ppm as CaCO3. The water was then heated to 120-130 °F and 1 percent neutral soap powder contain ng no additives and 0.1 percent soiling medium was added. The mixture was stirred and allowed to stand in contact with the specimens for about 30 min. The tank was drained and the specimens allowed to dry overnight. Another experiment was tried, using a superfatted soap in place of the soap powder. However, in both cases, the "synthetic bathtub ring" was easily removed by dry wiping, as shown visually and by examination under ultraviolet light, which fluoresces the anthracene. This did not

appear to be a promising approach, because of the ease with which the soil could be removed.

e. Recommendations for Future Development (1) Soiling Agents

An essential starting point for the development of test procedures for both soilability and cleanability is a reproducible soiling agent that suitably simulates actual soiling materials in sanitary plumbing fixtures. Actually, typical soiling agents may differ for bathtubs, lavaboratories, sinks, water closets, etc.

Based on the laboratory experience obtained during this investigation, it is considered necessary to explore actual bathtub soiling materials involving hard water, bath soap, and human subjects. Analysis should be made of bathtub soil to determine the nature and proportions of various constituents as a basis for synthesizing a representative standard soiling medium. Consultation with the manufacturers of toilet soap and detergents is desirable as a means for identifying the principal ingredients in soaps and to reduce the amount of research and analysis required. It is considered possible to develop a standard soiling agent that will suitably simulate the chemical composition, color, adhesion properties, hardening and drying properties, etc., of actual soiling agents, and which can serve as a basis for performance tests on soilability and cleanability."

(2) Evaluation of Accumulation

It is probable that, with some initial experimentation in whole bathtubs, the soiling process can be adequately studied on flat samples cut from bathtubs or shower stalls, using a small-scale apparatus. In this event, the accumulation of soil could probably be determined by weight, with or without removal from the surface.

(3) Soil Removal by Scrubbing

It is probable that the essential measure of cleanability is the amount of energy or work required to remove the soiling agent and produce an appearance of aesthetic cleanliness. This involves the cleaning device (brush, sponge, cloth, etc.), the cleaning agent (detergent or scouring powder), the pressure used in scrubbing, the force required to move the scrubbing element across the surface of the specimen, and the number of strokes over the surface. Existing methods do not attempt to evaluate cleanability in these terms. These parameters of the scrubbing process all vary widely in actual practice.

It would be highly desirable to standardize the elements of the scrubbing process if meaningful comparisons are to be made for different materials. If the soiling process can be effectively produced on flat samples in a small-scale apparatus, it would

be possible to use the Gardner Heavy Duty Wear Tester, equipped with suitable brushes or sponges, under a standard pressure, and a standard nonproprietary detergent or scouring powder, to determine the amount of scrubbing effort required to clean a surface or to compare the cleanability of various surfaces. It might be desirable to use a liquid detergent as the cleaning agent rather than a scouring powder, to avoid possible problems of particle imbedment in the scrubbing element, and to magnify any differences that might exist in the number of strokes or work required to attain a given level of cleanliness.

(4) Evaluation of Aesthetic Cleanness

White-light reflectance is presently used (sec. 2.11d) to indicate the amount of soiling medium remaining on a surface after cleaning. The soiling medium used in the test contains black pigments which reduce the reflectance of a white or lightcolored surface, which has a high white-light reflectance before soiling. In attempting to correlate this method for evaluating cleanability with aesthetic cleanness, it must be established that natural dirt also reduces white-light reflectance of the surface and that the change in reflectance is related to the amount of dirt.

The test described in section 2.11d gives an indication of the amount of soiling medium retained in the scratches on the surface resulting from abrasion. Hence it is an indication of abrasion as well as cleanability and soilability and was designed as an indicator test for abrasion. It seems likely that, with further work to correlate visual response, type and quantity of soil, and reflectance, white-light reflectance could be used as a measure of aesthetic cleanness of white sanitary ware. The apparatus is commercially available, it is sufficiently sensitive to simulate visual resolution, and a fairly good correlation between white-light reflectance and visual response has already been established.

The white-light reflectance of a dark-colored surface is low and there may not be sufficient contrast between the surface and the soiling medium or natural dirt to indicate the amount of soiling. Hence the method outlined in section 2.11d may not be valid and white-light reflectance may not be a good indication of cleanness or abrasion of colored sanitary ware. Some additional research work would be needed to develop suitable modifications of the procedure for colored plumbing fixtures. This might take the form of a different coloring agent in the standard soiling medium. Correlation between reflectance measurements on colored surfaces with various degrees of soiling and visual responses would also be needed.

Soilability and cleanability tests should be carried out on both new specimens and abraded specimens.

2.12 Surface-Impact Resistance (Bathtub)

(M204)

a. Purpose and Scope

The purpose of this test is to determine whether or not the finished surface of a bathtub will withstand certain impact loads on critical areas without suffering mechanical damage. The impact load imposed by the recommended test is a blow on a rounded edge of the rim by an aluminum tube mounted on the end of a pendulum.

b. Recommended Test Method

(1) Apparatus

The apparatus shall be as shown and described in figure 2.12-1. Essentially it is a pendulum-type impact device made so that the tup (striking part) strikes the inside convex corner of the front rim of the bathtub at an angle of 45° from the horizontal. (2) Preparation of Test Specimen

Place the bathtub on the floor and level it. Use framing and/or shims when required to prevent rocking or shifting of the specimen when tested. In addition, distribute sufficient weights in the bottom of the bathtub to provide approximately 250 lb of total weight including the weight of the bathtub.

Inspect the test area prior to the test using the procedure outlined in section 2.8. Test only those areas without defects. Make certain that each test point is at least 2 in from any defective or damaged area.

(3) Test Procedure

Maintain the temperature of the testing laboratory and bathtub at 75±5° F. Position the test apparatus so that the center of the tup will strike the test surface at an angle of 45° with the horizontal. This procedure is illustrated schematically in figure 2.12-1. Select the area for test along the inside convex corner of the front rim. Test a total of 10 points.

Drop the pendulum against the test surface in 1-in increments of height-of-drop until cracking, chipping, or other damage in the surface is observed, or until a 30-in height-of-drop is achieved. Inspect for damage to the surface using the procedure outlined in section 2.8. Rotate the tup slightly after each point is tested so that a new area of the tup strikes the test point. Record the height-ofdrop of the pendulum when the damage occurs, and describe the damage.

(4) Information to be Reported

Include the following in the test report:

1. Specimen identification;

2. Location of the 10 test points indicating the distance of each from the drain end of the tub;

3. The height-of-drop for cracking, chipping, or other damage at each point;

4. Description of the damage.

c. Test Results and Discussion

(1) Test Development

Several test methods were tried prior to the development and selection of the recommended method. The first method tried (table 2.12-1) involved the use of a 12-lb steel ball 112 in in diameter as the striking object. This method was essentially as described in the proposed revision of CS 221-59 [1] except that a plastic cylinder fitted with bubble-type plumb devices was used as a guide tube. The steel ball was allowed to fall free from various heights on both flat and curved surfaces of the specimens. The results of these tests indicated that

the convex surfaces of the tubs were most susceptible to damage. It was also noted that the precise point of impact was critical. The steel ball test was abandoned because of difficulty in controlling the point of impact on the convex surfaces, and also because the high rigidity of the steel ball was not characteristic of objects likely to be dropped on bathtubs after installation. A second series of tests was tried with a pendulum apparatus similar to the recommended apparatus except that the tup used was a glass bottle. Variations in weights and dimensions of bottles of the same nominal size plus the danger from glass breakage led to the use of an aluminum cylinder as the striking object. (2) Test Data

The results of tests on a number of porcelainenameled-steel tubs are presented in table 2.12-2. The reported results are confined to porcelainenameled-steel tubs only although porcelain-enameled cast-iron and FRPE tubs were also tested. The results of tests on cast-iron units are not included in table 2.12-2 as no failures occurred at the maximum height-of-drop. The same was true for the FRPE tubs with one exception. Specimen PB-2 at a point of double curvature failed at an average height-of-drop of 1814 in for eight test points. Nine test points located at areas of single curvature withstood the maximum height-of-drop without damage.

The results tabulated for other test areas in table 2.12-2 are included to show that a definite test area must be specified since differences in impact resistances among different areas of the same specimen are significant.

The primary reason for the selection of this method of test was that the height-of-drop and the point of impact can be easily controlled and reproduced. The selection of aluminum as the material for the tup was prompted by the similarity of its modulus of elasticity to that of glass.

The inside radius of the front rim was chosen as the test area because this area is vulnerable to impact blows in normal service, and is conveniently located for testing with the apparatus developed for this test.

d. Comments on Performance Requirements (1) Suggested Format for a Performance Level The average of the heights-of-drop at first cracking, chipping or other damage for the 10 test points shall be not less than in. The minimum value for any one point shall be

(2) Rationale for Suggested Format

in.

That chipping occurs on some steel tubs is indicated by the results of the telephone survey (Appendix B). In setting height-of-drop limits, however, it should be kept in mind that about 34 of the chips occurred during, or prior to, installation. More care during handling and installation probably would have reduced the observed damage by a sizable amount.

2.13. Dimensional Stability (M205)

This characteristic was defined by the ad hoc committee as the ability of a plumbing fixture to withstand the conditions of environmental exposure in service, and the conditions of normal handling and storage prior to installation without

excessive distortion. There is no existing test method applicable to the determination of this property for sanitary plumbing fixtures and no test method is recommended. Extensive experimentation would be required to devise accelerated tests to evaluate permanent distortion in service in relation to time of use. Some data on permanent distortion after exposure to concentrated load separately and in combination with a water load are presented herein. Some data on permanent deflection during the hot-water resistance test are also presented.

2.14. Bond Maintenance (Mechanical)

(M206)

Commercial Standard CS 221-59 specifies that FRPE specimens exposed to the ASTM B 117 salt spray test for 4000 hr [22] shall not exhibit any "apparent" blistering, delamination, or other surface defects. No work was done on a test for this property in the present investigation. The tests recommended in sections 2.2, 2.4, 2.18, and 2.20 covering concentrated static load, concentrated dynamic load, hot-water resistance, and radiantheater resistance, respectively, are believed to expose the fixture to some of the more severe service conditions that are likely to produce delamination or loss of bond. These tests should indicate the ability of the fixture material to maintain the bond between the structural back-up and the surface finish under service conditions.

2.15. Surface Slip Resistance (Bathtub or Shower Receptor) (M207)

a. Purpose and Scope

The purpose of this test is to evaluate the surface slip resistance of bathtubs and shower receptors. This property obviously is related to safety in the use of these fixtures.

b. Selection of a Test Method

No test method can be recommended at this time, because none of the existing test methods appear to be suitable, and it was not possible to develop a suitable method within the resources available in the present investigation. Three major elements would be pertinent to a suitable method:

(1) The sliding element of the test apparatus should effectively simulate the surface properties and resilience of some part of the human anatomy likely to be involved in slipping in a bathtub or a shower receptor. These properties would have to be determined through further study.

(2) The method of initiating slippage, i.e., dynamically or statically induced, would have to be selected from further information on falls in service (or other simulated service conditions) so

as to effectively simulate the mechanisms of slippage in bathtubs and shower receptors.

(3) The nature of the fluid film to be used on the test surface should be selected from further study so as to simulate service conditions.

Finally, a relation between slip-resistance values determined in tests and actual slippage by human subjects (suitably protected against injury) in a service or simulated-service environment, using the same materials, would be highly desirable.

c. Discussion of Existing Test Methods

Two reports [23, 24] relating to test methods and apparatus for determining slipperiness of walkways were studied.

In horizontal-track methods, the sliding coefficient of friction at constant velocity is the ratio of the force required to drag the specimen to the weight of the sliding body, neglecting intermolecular forces between the surfaces. In inclined-track methods, the coefficient of friction is determined by the tangent of the angle of incline of the plane surface to the horizontal. The angle is adjusted until constant velocity is attained. The Sigler Slip Tester, a pendulum-impact machine, developed at the National Bureau of Standards for testing slipperiness of walkway surfaces, was based on the premise that, in the process of walking, slipping is most likely to occur when the rear edge of the heel contacts the walkway surface. The value obtained from use of the machine, the energy loss in a measured distance of movement across the surface, is called the "anti-slip" coefficient.

The simplest method, a horizontal-track method for floor surfaces, used by the Research Department of the Hospital Bureau, Inc., employs a 15lb spring scale and an 8- X 10-in canvas bag containing 10 lbs of lead shot. The bag is placed on two layers of clean cheesecloth with the scale attached. If less than a 3-lb drag will pull the bag across the floor, the surface is considered too slippery. If a drag of 5 lbs or more is required, the floor is considered safe. However, it was reported that the results depend on operation and technique. Possibly a modification would be suitable for testing the slipperiness of bathtubs and shower receptors.

Another horizontal-track method is the Egan Slip Tester, manufactured by the Thwing-Albert Instrument Co., Philadelphia, Pa. Friction is measured between two specimens, one secured to a moving platform and the other attached to a weighted sled connected to a spring dynamometer or electric load cell. This would not be suitable for measuring the slipperiness of sanitary ware, because only one surface of the sanitary ware is involved in slipping in a bathtub or shower receptor, while two surfaces are involved in the Egan Slip Tester.

Friction of floors has been studied by means of a household floor scrubbing and polishing unit,

the power supply of which is connected to an ammeter. Increased current indicates greater friction and vice-versa. However, the brush is not similar in surface properties to the human foot or other part of the anatomy which might slip in a bathtub or shower receptor.

Another type of horizontal-track method, measuring static friction instead of kinetic friction, is represented by the Hunter Machine, the James Slip Tester, and the Dura Slip-Resistance Tester, all similar in principle. The Hunter Machine consists of a slotted weight, placed between two vertical guide bars of the frame, and a thrust arm pivoted at one end near the center of gravity of the weight and at the other end through the center of a shoe. The sliding specimen, a footwear material, is attached to the underside of the shoe and rests on the track, a flooring material. Initially the shoe is placed with the thrust arm close enough to the vertical so that the specimen will not slip on the track. By means of a screw and lug, the shoe can be drawn forward by small increments, increasing the horizontal component of the shoe until the specimen slips on the track and the weight drops. The position of the lug at the instant of slippage is an indication of the frictional force. This method seems deficient because the relationship between frictional properties of footwear materials and the sole of the human foot is unknown, and the method of initiating slippage seems unlike that involved in falls in bathtubs and shower receptors.

The Sigler Slip Tester is essentially a compound pendulum which sweeps a shoe material over the walkway surface to be tested. A mechanical shoe, forming the lower end of the pendulum, is so arranged that a test piece of rubber, leather, or other heel material, 112 in square, can be attached to the underside of the shoe at an angle of 10, 20, or 30 degrees to a horizontal plane. A helical spring is used to press the edge of the heel against the walkway surface. The pendulum, released from a predetermined fixed height, is allowed to sweep over the floor specimen or surface to be tested. A pointer attached to the framework at the pendulum's center of rotation records the heights to which the pendulum swings beyond the floor specimen after contact. From the data, an anti-slip coefficient between the two materials is determined. Deficiencies of this method are similar to, but possibly less serious than, those of the Hunter method.

The British Portable Skid-Resistance Tester [25] is an improved modification of the Sigler Slip Tester, designed for measurements on walkways and roadways. It is also the basis of a proposed ASTM method for measuring surface frictional properties. The slider assembly consists of an aluminum backing plate to which is bonded a 14 X 1-X 3-in rubber strip. The rubber compound is synthetic rubber as specified in ASTM E24964T [26] and must not be more than 2 years old.