Chemical Stability Testing Standards for Borosilicate Glass

Borosilicate glass is widely used in laboratories, chemical equipment, and industrial sight glasses due to its excellent chemical stability. This stability determines how well the glass resists corrosion, leaching, and surface degradation when exposed to aggressive chemicals. To ensure consistent performance, internationally recognized testing standards are applied to evaluate the chemical durability of borosilicate glass.

One of the most important references is ISO 719 and ISO 720, which focus on the hydrolytic resistance of glass. These standards measure how much alkali is released from the glass surface when it comes into contact with purified water under controlled temperature and time conditions. Borosilicate glass typically achieves Class 1 hydrolytic resistance, indicating extremely low ion release and excellent resistance to water-based chemical attack.

For acidic environments, ISO 1776 is commonly used. This test evaluates the resistance of glass to acidic solutions, such as hydrochloric or nitric acid, by measuring mass loss after exposure. High-quality borosilicate glass shows minimal surface erosion, confirming its suitability for chemical reactors, pipelines, and sight windows where acidic media are present.

Alkaline resistance is assessed under ISO 695, which focuses on glass behavior in alkaline solutions like sodium hydroxide. While borosilicate glass performs well against acids and water, it is more vulnerable to strong alkalis at elevated temperatures. The test results help engineers determine safe operating limits and select appropriate glass thickness or protective coatings.

In addition to ISO standards, ASTM C225 and DIN 12116/12111 are also used in certain regions to evaluate chemical durability. These standards provide complementary data for international projects and regulatory compliance.

In practical applications, chemical stability testing ensures that borosilicate glass maintains optical clarity, mechanical strength, and long service life. For industries such as pharmaceuticals, petrochemicals, and laboratory research, compliance with these testing standards is essential to guarantee safety, reliability, and long-term performance under chemically demanding conditions.