An antifoam, also known as defoamer or antifoaming agent, is a chemical additive used to control or eliminate foam in industrial processes or products. Foam can be generated in various industrial processes such as fermentation, wastewater treatment, food processing, and manufacturing processes involving liquids.

Foam formation can lead to several issues including reduced efficiency of industrial processes, overflow of containers, and contamination of products. Antifoams work by breaking down foam bubbles or preventing their formation altogether. They typically contain surface-active agents that disrupt the foam structure, causing the foam bubbles to collapse or coalesce into larger bubbles that break more easily.

Antifoams come in various forms including liquids, emulsions, powders, and compounds, and they are chosen based on the specific requirements of the process or product. They are used in small quantities and are carefully selected to ensure compatibility with the system and effectiveness in controlling foam without adversely affecting the desired properties of the end product.