Corks and Stoppers: Choose and Use Guide
Sargent Welch black gum rubber stoppers are specially compounded to achieve the resiliency, softness, durability and gripping qualities most favorable to chemical laboratory requirements. These stoppers are recommended for all general applications because of their very low sulfur content. Sizes are standardized with size numbers molded into the top of each. View the chart below to determine which rubber stopper is best for your laboratory or classroom.
XXXX Quality Corks have a fine grain and are ideal for use as tight-fitting stoppers. View the chart below to determine which cork is best for your laboratory or classroom.