posure in existing tests, and (2) lack of information to correlate temperature levels and the number of cycles to produce failure. It is recommended that further work be directed toward the development of a suitable test that would replace both the hot-water resistance tests described in section 2.18 and the existing thermal-shock tests described in section 2.21. A discussion of these matters is given in section 2.21.

The blistering of FRPE bathtubs observed during the hot-water resistance tests described in section 2.18 was probably not the result of thermal shock. It may have been the caused by differential expansion of the gel-coat and the substrate, or more likely by volatile products given off by the substrate at the elevated temperatures. Therefore, the combination test procedure proposed above should incorporate a cumulative long-term exposure of a bathtub to warm water, together with a cyclic thermal-shock test at different temperatures.

3.4. Other Characteristics Requiring Test Development

There was a number of performance characteristics for sanitary plumbing fixtures that were considered important by the ad hoc committee, but which were excluded from the present test development effort either because (1) accounting for all the relevant parameters made the investigation too complex and costly or (2) the particular scientific discipline principally involved was not available at the National Bureau of Standards. These characteristics include the following:

Dimensional Stability (M205)
Noise Control (N401) (N402)
Surface Texture Aging (C504)
Odor (C505)

Biological characteristics (B601) (B602)
(B603)

These characteristics should be considered in any future program of test development for sanitary plumbing fixtures.

[1] Standard for gel-coated glass-fiber reinforced polyester resin bathtub units, a proposed revision of Commercial Standard CS 221-59 (Aug. 1964). [2] Gel-coated glass-fiber reinforced polyester resin bathtubs, Commercial Standard CS 221-59.

[3] Plumbing fixtures, land use, Federal Specification WW-P-541b (4) (1962).

[4] Enameled cast iron plumbing fixtures, Commercial Standard CS 77-63.

[5] Method of test for water absorption of plastics, ASTM designation: D 570-63.

[6] Vitreous china plumbing fixtures, Commercial Standard CS 20-63.

[7] Earthenware (vitreous-glazed) plumbing fixtures, Commercial Standard CS 111-43.

[8] Standard methods of test for abrasion resistance of porcelain enamels, ASTM designation: C 448-61. [9] Schiefer, H. F., Crean, L. E., and Krasny, J. F., Improved single-unit Schiefer abrasion testing machine, Research Paper RP 1988, NBS J. Research, 42 (May 1949).

[10] Richey, G. G., McKenna, E. H., and Hobbs, R. H.; Methods and equipment for testing printed-enamel felt-base floor covering, NBS Building Materials and Structures Report No. 130 (1952). [11] Tentative specifications and methods of test for laminated thermosetting decorative sheets, ASTM designation: D 1300-53T.

[12] Standard method of test for mar resistance of plastics, ASTM designation: D 673-44.

[13] Standard method of test for abrasion resistance of paint, varnish, lacquer, and related products by the falling sand method, ASTM designation: D 968-51.

[14] Standard method of test for abrasion resistance of coatings of paint, varnish, lacquer, and related products with the air blast abrasion tester, ASTM designation: D 658-44.

[15] Marra, Dorothea, and Osipow, Lloyd I., A review of Snells's soiled cloth, Detergent Age (Oct. 1964, p. 52).

[16] Enamel; interior, semigloss, tints and white, Federal Specification TT-E-508 (4) (1953).

[17] Shelberg, Wesley E., Mackin, James L., and Fuller, Ross K., Artificial surface dirts for detergency studies with painted surfaces, Ind. Eng. Chem., 46, No. 12, 2572 (Dec. 1954).

[18] Ridenour, G. M., and Armbruster, E. H., Bacterial cleanability of various types of eating surfaces, Am. J. Public Health, 43, No. 2, 138 (Feb. 1953). [19] Armbruster, E. H., and Ridenour, G. M., Field test procedures for cleanliness measurement of multiple use of eating utensils, The Sanitarian 23, No. 2, 103, (Sept.-Oct. 1960).

[20] Wells, Louis E. Jr., A progress report, Part II, Test methods for evaluating liquid detergents for hand dishwashing, Proc., 43rd Annual Meeting, Chemical Specialties Manufacturers Association, Washington, D.C., (Dec. 3-5, 1956). pages 189-191. [21] Weatherby, Robert J., The measurement of floor dirt, J. Environmental Health, 26, No. 4 (Jan.Feb. 1964).

[22] Standard method of salt spray (fog) testing, ASTM designation: B 117-61.

[23] Causes and measurement of walkway slipperiness, Federal Construction Council Technical Report No. 43, Report of Task Group T-41, Building Research Advisory Board, National Academy of Sciences-National Research Council, Washington, D.C., 1961.

[24] Causes and measurement of walkway slipperiness, Publication No. 899, National Academy of Sciences-National Research Council, Washington, D.C., 1961.

[25] Giles, C. G., Sabey, B. E., and Cardew, K. H. F., Development and performance of the portable skid-resistance tester, Road Research Paper No. 66, Department of Scientific and Industrial Research, London, England (1964).

[26] Tentative specifications for standard tire for pavement tests, ASTM designation: E 249-64T. [27] Test for resistance of porcelain enamels to gouging, Bulletin T-1, Porcelain Enamel Institute, Inc., Washington, D.C. (1942).

[28] Formed metal porcelain-enameled sanitary ware, Commercial Standard CS 144-47 (under revision).

[29] Tentative method of test for resistance of plastics to sulfide staining, ASTM designation D 171260T. [30] Tentative method of test for staining of poly-(vinyl chloride) compositions by rubber compounding ingredients, ASTM designation: D 2151-63T. [31] Tentative recommended practice for operating water-cooled xenon-arc type apparatus for artificial light exposure tests, ASTM designation : E 240-64T.

[32] Tentative recommended practice for operating enclosed carbon-arc type apparatus for artificial light exposure tests, ASTM designation: E 188-63T. [33] Recommended practice for operating light- and water-exposure apparatus (carbon-arc type) for artificial weathering test, ASTM designation: E 42-57.

[34] Recommended practice for operating light- and water-exposure apparatus (carbon-arc type) for testing paint, varnish lacquer, and related products, ASTM designation: D 822-60.

[35] Hunter, R. S., Photoelectric tristimulus colorimetry with three filters, NBS Circular C429 (1942). [36] Tentative recommended practice for operating lightand water-exposure apparatus (carbon-arc type) for exposure of plastics, ASTM designation: D 1499-59T.

[37] Standard methods of test for resistance of plastics to accelerated service conditions, ASTM designation: D 756-56.

[38] Method of test for color difference using colordifference meters of the Hunter-lab or Gardner types, ASTM designation: D 1365-60T.

a. Purpose and Scope

A five-man inspection team from NBS, assisted by BRAB consultants and FHA representatives, visited three plants engaged in the manufacture of FRPE sanitary plumbing fixtures and made on-site field inspections of 37 fixtures that had been in use for periods ranging up to three years. Test facilities were also observed. The field observations on FRPE fixtures were limited to bathtubs and shower receptors.

The purpose of the trip was twofold: (a) to become familiar with current manufacturing and testing processes for FRPE plumbing fixtures, and (b) to inspect as many installed fixtures as time would allow. The overall goal was to permit the NBS team to obtain a background on FRPE plumbing fixtures before embarking on the BRABsponsored program to select or develop performance tests for sanitary plumbing fixtures fabricated from any material.

b. Manufacturing Processes

There were many similarities in the operations observed at the three plants that were visited. All three used a highly-polished black plastic mold, which is a male image of the desired fixtures. A wax parting compound was first rubbed on the mold surface, after which a polyester gel-coat was applied by hand-spraying with a special spray gun to a thickness of approximately 0.020 in. The required amount of catalyst was metered in the gun so as to provide hardening of the gel-coat within 30 to 45 min after spraying. The white gel-coats appeared to be opacified with titanium dioxide. The appearance of the finish was similar to porcelain enamel. Its smoothness and gloss depended on the polish imparted to the mold prior to spraying.

After the gel-coat hardened, the fiberglass backing was applied. Two of the three plants used the sprayed-glass process. In this process, glass yarn was fed into a special spray gun where it was chopped into fibers 5% to 34 in long before being propelled along with the polyester and catalyst against the previously gel-coated mold. The resincoated fibers did not flatten out against the back of the gel-coat, but rather deposited as a loose mat. This required a hand-rolling operation in which the operators used steel rollers to compact the layer. This was done periodically throughout the spraying operation. The thickness of the backing as well as thickness uniformity appeared to depend to a considerable extent on the skills of the spraygun and roller operators with the methods and equipment being used.

In the glass-fabric process the gel-coated mold was first brushed with a polyester varnish to which the proper amount of catalyst had been added. Sheets of glass mat and glass fabric were then placed over the polyester and hand rolled into position.

The total thickness of the walls of the fixtures manufactured at all three plants was of the order of % to 4 in. Since this was insufficient to provide the required rigidity, reinforcements were glued to the back surfaces before removal of the fixtures from each mold. Each manufacturer used a different type of backing reinforcement such as plywood, pressed hardboard, gypsum wallboard, or plastic ribs.

Mold removal occurred as a final operation. This was done by applying air pressure at the edges.

All three plants manufactured bathtubs of the same basic design, i.e., a tub with an integral front apron and a wall surround extending above the top of the tub to a maximum of approximately 4 feet. The wall surround was flanged with an edging strip about 1⁄2 in wide for nailing to the studs during installation. A few bathtubs with no wall surround were being produced, but this type of fixture represented only a small percentage of the total production.

c. Inspection of Installed Fixtures

A total of 37 plastic fixtures was inspected in the geographical areas adjacent to the manufacturing plants. However, all units inspected in a given area were not necessarily manufactured by the plant that was visited in that area. The age of the fixtures inspected ranged from a few months to approximately three years. Production methods and quality control procedures had been changed in some instances since the first of these fixtures was manufactured.

The inspections were intended as spot checks. They were not arranged by the manufacturers except in one midwestern area where time limitations prevented a more objective selection of installations.

The help of local FHA officials was used in locating housing developments where plastic fixtures had been installed. The selection of installations was largely random after the development was reached. Normally, three teams of two persons each made the inspections. Arrangements for the inspections were made in most cases by one of the team members talking to one of the occupants of each of the selected houses. Detailed observations were recorded by the NBS team for the information of BRAB staff and the project staff. From this information, several comments can be made:

(1) Installation Method

The plastic bathtubs were attached to the wall studding by nailing through the edge strip provided for this purpose on both the front apron and on the wall surrounds. In some cases cracking of the edge strip was observed. The observed cracks did not extend into the part of the fixture intended to be visible after installation of the bathroom walls. One manufacturer recommended screws for this purpose and predrilled the edging strip. However, one such fixture inspected in a house under construction showed that the installer had nevertheless used nails rather than

screws.

All of the plastic fixtures inspected had a bottom slope adequate to provide complete draining of cold water introduced into them. The bottom slopes varied from 0.2 to 4.2 percent with a median of 2.5 percent. The top ledges showed slopes of -0.6 to +1.1 percent, but most were installed level.

(2) Cleaning Methods and Cleanability

Although all manufacturers recommended that the tubs not be cleaned with harsh scouring powders, about 80 percent of the occupant interviewed reported that they used proprietary brands of scouring powders. A cleanability test convenient for field use was made during each inspection in which a 3B drawing pencil was used to make marks on the surface of the fixture. On a newly installed bathtub

the pencil marks could normally be removed by dry rubbing. Once the gloss had disappeared, however, it was necessary to use soap (Ivory) and water to obtain removal. On about 19 percent of the fixtures it was necessary to use scouring powder (Bon Ami). In no case was it impossible to remove the marks with the scouring powder.

(3) Scratching of Gel-Coat

Almost all of the fixtures inspected had one or more visible scratches. In general, these scratches were visible only on close inspection and did not appear to affect cleanability as determined by the 3B pencil test.

(4) Cracking of Gel-Coat

About half of the fixtures showed one or more fine cracks in the gel-coat. The depth of the cracks was not ascertained.

(5) Gouging of Gel-Coat

Small gouges in the gel-coat were observed in three of 37 fixtures.

(6) Chemical Stains

Chemical staining was observed on four of the 37 fixtures. In one case the staining apparently had resulted from use of a rubber mat in the bottom of the tub, while in the other three, the stain had probably been caused by rusting of iron objects (possibly bobby pins or metal toys).

(7) Cigarette Burns

Three tubs showed cigarette burns on the outer ledge. Two of these were in motel units and the third in a private home. It was found in the home fixture (FHA repossessed) that the discolored area could be removed by a vigorous and prolonged localized scouring with "Bon Ami."

(8) Impact Damage

There was no positive evidence in any of the inspected plastic fixtures of complete loss or penetration of gel-coat from impact of a falling object. However, one fixture was found where a star-shaped crack pattern in the gel-coat on the wall surround suggested that an impact from the reverse side might have occurred previously.

(9) Rigidity and Strength

Several fixtures (two or three years old) exhibited considerable flexibility, especially in the wall surround, and some fixtures exhibited a "cracking noise" when pressed firmly with a foot or a hand. This condition suggested either a possible separation of the reinforcement strips from the fiber-glass-resin backing, or insufficient rigidity of the reinforcement as designed. No structural failures were observed in any of the fixtures.

(10) Spalls and Pits

Small spalls or pits, approximately 16 in to %-in diam, were detected on the bottom of about 80 percent of the bathtubs which had been installed for periods of two to three years. This percentage decreased to 35 percent on the fixtures installed from one to two years while none of these defects was observed on the fixtures installed for one year or less.

(11) Lifting of Gel Layer (Delamination)

Several examples of separation of the gel layer from the fiberglass-resin backing were observed. In one case water could be squeezed out of a break in the coating by pressing down on the raised portion of the gel-coat.

(12) Apparent Slip Resistance of Gel-Coat

Two members of the inspection team who took baths in FRPE tubs installed in their motel rooms reported a feeling that the tubs were less slippery than conventional porcelain-enameled fixtures.

The manager of a development for retired people reported no injuries from falls in bathrooms since the development started. He ascribed this absence of injury to the plastic fixtures. All of these homes (est. 1,000 completed) were equipped with deep shower receptors with integral seats.

(13) Field Repairs of Plastic Fixtures

Several field-repaired fixtures were inspected. Some owners reported reappearance of defects after a relatively short period of service following repair.

(14) Comments on Customer Acceptance

Although no comments from occupants were solicited during the field inspections, opinions and comments were nevertheless frequently volunteered. Some dissatisfaction was evidenced in a number of cases where defects requiring field repairs had appeared. One comment, volunteered during many of the inspections, was that the FRPE fixtures were not only more difficult to clean than porcelain-enameled fixtures, but that even after cleaning they did not look as "clean" as a porcelain-enameled fixture. On the other hand, many favorable comments were heard on the absence of a tub-to-tile seam with the FRPE fixture. Some users commented favorably about apparent slip resistance.

d. Suggestions Regarding Needed Test Based on Field Observations

The comments given below regarding needed tests for sanitary plumbing fixtures were developed immediately following the field inspection trip as a result of the field observations, and preceded the initiation of laboratory work. In fact, the substance of these comments was later found quite useful as guideline material in actual test development work and in formulating recommendations. For these reasons, it is appropriate to present the comments here.

(1) Delamination

Separation of the gel-coat from the fiber-glass-resin backing, if it occurs, is a serious defect from the standpoint of sanitation and fixture usability. A suitable hotwater resistance test might reveal tendencies to delamination and spalling of the gel-coat.

(2) Cracking or Crazing of Gel-Coat

Cracking of crazing of the gel-coat is undesirable from the standpoint of sanitation and ease of cleaning, and may permit water entry into the fiber-glass-reinforced plastic. A hot-water resistance test might reveal susceptibility to crack or craze.

(3) Gel-Coat Thickness

In a performance specification a gel-coat thickness requirement does not seem appropriate. Instead it might be better to require that the coating withstand a minimum number of abrasion cycles under specified conditions.

(4) Bond Between Fiber-Glass-Resin Backing and Reinforcing Strips

A test of the bond strength of reinforcing strips should not be a part of a performance specification. The integrity of the bond could probably best be evaluated by specify

ing maximum permissible deflection during localized loading and measuring the deflection with respect to the immediate vicinity of the loading point.

(5) Abrasion Resistance

This is an important property, since the field inspection indicated that owners continue to use scouring powder for cleaning in spite of instructions to the contrary from the manufacturer. A suitable abrasion test should take into account the portable number and severity of scouring treatments during the desired period of service life.

(6) Stain Resistance

The field inspection indicated that stains had not been a serious problem with FRPE tubs except possibly stains from cigarette burns. The criterion for stain resistance might possibly be related to the thickness of coating that would have to be removed to eliminate the stain.

(7) Aging

No installations were inspected that had been in service for longer than three years. It might be desirable to have an accelerated test to indicate whether or not the properties of the material would change appreciably with time at approximately room temperature.

(8) Hardness and Scratch Resistance

One of the unexpected findings from the field inspection was that scratches, while present, were not especially noticeable and, furthermore, they had little effect on the pencil cleanability test employed in the field inspections. Nevertheless, it seems important that a scratch test be included in a performance specification.

(9) Cleanability

The field inspections indicated that cleanability is important to the user. A suitable test should measure the ease with which a standard soiling agent can be removed.

e. Test Facilities

The NBS inspection team visited one commercial testing laboratory, one industry research laboratory, and one fixture manufacturer's laboratory. The impression obtained was that each of these laboratories had been conducting several of the tests called for under CS 22159, and had become familiar with these tests. The manufacturer's laboratory was set up for the primary purpose of quality control of FRPE fixtures, and was well equipped for this purpose. The industry research laboratory was concerned with evaluating or developing tests for a broad spectrum of building products and materials, and was well equipped for making several of the important tests called for by CS 221-59. The commercial testing laboratory visited evidently made only certain tests on plumbing fixtures, principally the structural and mechanical tests.

Two of the three manufacturing plants visited evidently did not make on the premises the test described in CS 221-59, but conducted inspection and made empirical process control adjustment. These two plants did not conduct routine tests on the quality of the gel-coat materials, but purchased the product from well-known suppliers according to specification.

This brief inspection of test facilities should not in any sense be construed to indicate an evaluation of the laboratories visited. The only purpose was to obtain some familiarity with the test apparatus and procedures used in evaluating FRPE fixtures made to existing standards.