Journal of the American Ceramic Society

Zwermann, C. H.; Andrews, A. I.

doi: 10.1111/j.1151-2916.1940.tb14214.xpmid: N/A

Abstract Various opacifiers were added in increasing percentages to clear, regular white, very opaque white, and acid‐resisting enamels. These were ground to various degrees of fineness from coarse down to a few microns or finer; they were applied to sample plates and their reflectances were measured. Increased opacity is obtained by extremely fine milling because of the excellent dispersion of the opacifiers.

Spencer‐Strong, G. H.; McMahon, L. J.

doi: 10.1111/j.1151-2916.1940.tb14215.xpmid: N/A

Abstract The two general types of scumming and their causes are discussed. The sulfate type of scumming is caused by sulfates either in the enamel materials or in the atmosphere to which the ware is exposed. Nonsulfate types of scums are usually caused by a combination of factors, which include underfiring, excess water vapor in the furnace atmosphere, fineness of grinding, and mill additions, especially clays and opacifiers.

Lorig, C. H.; Krause, D. E.

doi: 10.1111/j.1151-2916.1940.tb14216.xpmid: N/A

Abstract A summary is given of the tests which were conducted to appraise the utility of phosphorus steels in vitreous enameling. Enameling tests were conducted on both killed and rimmed steels of low‐carbon iron and steel with a phosphorus content up to 0.60%. Phosphorus was found to reduce the sag of laboratory‐prepared enameling stock to a marked degree. The most effective range of phosphorus was from 0.10 to 0.15%, and killed steels were superior to rimmed steels in their sag resistance. Phosphorus appeared to have no significant influence on common enameling defects. In amounts of less than 0.40%, it had no marked effect on the adherence of the enamel. The deep drawing qualities of the sheet, based on Olsen ductility tests, were somewhat impaired by phosphorus. This is in line with the strong tendency for phosphorus to raise the strength of the sheet.

Harrison, H. C.; Lawrence, W. G.; Tucker†, D. J.

doi: 10.1111/j.1151-2916.1940.tb14217.xpmid: N/A

Abstract A procedure, developed for the study of volatile glaze constituents, consists of heating the glazes beneath an absorbing medium which is subsequently tested by the spectrograph for the volatilizable constituents evolved. Data are presented showing temperatures at which certain important glaze constituents begin to volatilize, the order in which they leave the parent glaze, the influence of glaze composition on the volatilization temperature of each volatilizable constituent, and the effect of heat treatment on the volatilization temperatures.

Pavlish, A. E.; Silverthorn, R. W.

doi: 10.1111/j.1151-2916.1940.tb14218.xpmid: N/A

Abstract A new method for the determination of selenium in glass is reported. It comprises fusion of the sample with sodium carbonate, dissolution of the melt in sulfuric acid, distillation of the selenium as selenium tetrabromide from a sulfuric‐hydrobromic acid solution, and titration of the distilled selenium by the iodide‐thiosulfate method. The method is rapid, accurate, and precise and recovers all forms of selenium. The recommended procedure is outlined.

Preston, F. W.

doi: 10.1111/j.1151-2916.1940.tb14219.xpmid: N/A

Abstract This investigation shows that there is likely to be a severe concentration of stress in bottles or jars on the outside face of the junction of side walls and base when the bottles are subjected to a thermal gradient, that is, hot inside and cold outside. The stress in this area apparently may be two or three times as high as the general average, and its amount depends on the details of design at this point. A general formula, intended as a first approximation to the stress, has been worked out. That this region is a region of weakness is not news, but the reasons for it, as deduced in this study, are different from those generally given. Murgatroyd has shown that scratches on a bottle have a greater influence here than elsewhere and that their vulnerability is greatest if they are horizontal. His results are empirical, and he does not explain them. The explanation is given here.

SIEVERT, G. E.; Moffat, J.

doi: 10.1111/j.1151-2916.1940.tb14220.xpmid: N/A

Abstract The initial firing of some ceramic bodies is accompanied by a preliminary expansion before shrinkage takes place. This expansion, which has been determined for several types of ceramic bodies, may set up strains and result in the cracking of large pieces when they are improperly fired. A firing schedule that will lessen the strains and eliminate the cracking has been effected and is described in this paper.