The Simple Method for Increasing Chemical Stability of Glass Bottles

In tropical countries like Thailand, a defect called soda bloom is a common problem for glass manufacturers, particularly in a rainy season. Soda bloom occurs from the reaction between sodium in glass surfaces and water in the atmosphere. The presence of soda bloom depends directly on the hydrolytic resistance of glass. The poorer hydrolytic resistance is the more and easier soda bloom generates. Surface treatments are very promising for improving the hydrolytic resistance of glass surface. The purpose of this project was to find the treatment method that was not expensive but effective. 2.5wt% of alum (KAl(SO4)(2).12H(2)O)), 5wt% of alum, 5wt% of citric acid (C6H8O7), 5wt% of ammonium sulfate (NH4)(2)SO4 and 5wt% of acetic acid (CH3COOH) were used as solutions for surface treatments. The glass were rinsed by the solutions then cleaned and dried at 110 degrees C for 20 minutes. Results of the hydrolytic test (ISO 4802-1) showed that 5wt% of alum gave the most satisfying result. For the untreated glass, the consumption of 0.01M HCl solution per 100 ml of the extraction solution was 2.5 ml, while the treated glass with 5wt% of alum is only 0.9 ml. This indicated the decrease of leached sodium, in other words, the increase of hydrolytic resistance with only 0.05% margin increasing.