Some Effects of Storage on the Chemical Durability of Glass Containers

JSGT 1935 V19 T231-T243

 Tests on 4 oz medicine bottles of different makes and compositions but of similar shape showed that the conditions of storage (humidity, temperature, acid gases, prewashing) exercise a substantial influence on the changes in the glass surface both visually and as measured by the alkali extraction values. The outer surfaces tended to be slightly acidic after storage, whereas the inner surfaces were alkaline, most strongly so when the bottle mouth was capped so as to exclude atmospheric gases of acidic character. Using as basis of comparison the standard test of the Society of Glass Technology, according to which the bottles receive a preliminary washing immediately before test, storage was found to improve the durability of the inner surfaces of specimens of initial satisfactory durability, but the improvement did not hold good for unsatisfactory bottles. Washing prior to storage improved the durability measured after storage, both of good and of poor bottles; boiling with water also brought about improvement. Specimens stored without covers to their mouths underwent changes in their internal surfaces most rapidly, those closed by metal caps least rapidly. No definite conclusion could be drawn as to the effect of storage on the uniformity of the extraction value from individual bottles of a group. Some visible effects of surface changes are referred to. The weathering pattern known as “spider's web” appears to have its origin early in the life of the bottle.

Violet Dimbleby, H. S. Y. Gill & w. E. s. Turner