Enameled Utensil Manufacturers' Council Tentative Standard Solubility Test for Porcelain Enameled Cooking Utensils*

Abstract

Iiclative t o the control which must be exercised in conducting these tests, it is sufficient to say that this effect depends largely on the degree of accuracy required. Many factors in slip preparation as well as test methods were found to influence the results obtained, but sufficicnt standardization may readily be effected without undue effort or complication to permit results of acceptable accuracy for all practical purposes. For the sake of reliability, duplicate test runs are recommended when there is ally doubt as to the interpretation of a result or where close comparisons are required. In a majority of instances, however, a single test for any one property should suffice.Because ball-clay and kaolin slips contain divergent amounts of water and because different weights of slip were used in conducting the casting tests by the Biichner funnel method, no direct comparisons could be made of the casting time and water retention between a ball clay and a kaolin. Where such comparisons are desired, it may be found expedient to select such quantities of slip that a standard amount of clay is used in the funnel in contrast with the foregoing procedure in which both specific gravity and quantity of slip differ according to the type of clay used. The water content of slip could also be standardized, in which case an amount of water ( I 50'%) as previously used in the ball-clay slips would be satisfactory. Errors, however, E m meled Coo king 1 rte n s ils 11.7 resulting from the settling of aiiy particularly thin slil's thus prepared should be avoided.All tests were conducted on clay slips containiug a substantial proportion of nonplastic constituent. This procedure is recommended not only because of the reduction in testing time involved but because of difficulties inherent in the handling of 100% clay slips and the forming of satisfactory specimens. Whereas 50 clay-50 flint mixtures were adopted as the standard for a majority of the tests herein reported and would be satisfactory for general clay testing, i t is recommended for plant control that a nonplastic constituent of the amount and character employed in a production body of interest be used in combination with'the clay or clays under consideration; for example, feldspar or other nonplastic would partially or totally replace the flint according to the body composition itself. Test results simulative of production expectancy mould thus be obtained.It might be advisable in routine testing to increase the amount of nonplastic beyond the 50-50 ratio and to use a larger Biichner funnel because a reduction of testing time would probably result without too great a sacrifice of reliability. This procedure is recommended only for standardized routine testing purposes.ABSTRACT The various methods for determining the degree of resistance of porcelain enameled cookingware to acid solubility are discrussed. A method that overcomes many of the difficulties encountered in such a test and offers greater accuracy and reproducibility is described in detail.