Adaptation of Replica Technique to Measurement of Surface Durability of Glass

Abstract

A replica technique was developed for reproducing the corroded surface of glass containers. Before this development a wide variety of techniques had been studied which involved the use of various sheet plastics, such as ethyl cellulose, and various solvents. Most of the methods tried were of little value for curved surfaces because of the difficulties in pressing the plastic sheet uniformly upon the irregular contour of the bottle glass sample. A liquid plastic composed of Vinylite dissolved in methyl isobutyl ketone or acetone gave encouraging results when it was properly applied and dried. The previously weathered samples of bottle glasses were dipped in the plastic solution; after careful drying under controlled conditions, the plastic film was stripped from the surface to give an accurate reproduction of the corroded glass surface. The degree of surface deterioration, as shown by the replica, was then determined with a photoelectric haze meter. Some typical results taken from a study of various container glasses indicated that, as a rule, the inside of the container deteriorated; more rapidly than the outside. The pattern of corrosion on the outside of the container was quite irregular and was distinguished by long flowing lines, such as feeder marks, cutter marks, and mold marks. The inside of the container showed considerably fewer irregularities. Differences were found in the per cent haze vs. time curves for container glasses of varying composition. It was shown that these differences were generally associated with changes in the alumina and magnesia content of the glass.