Definition
Alkalis (singular: alkali) are basic chemical compounds that release hydroxide ions (OH⁻) in aqueous solution and exhibit a pH above 7. The most important alkalis include sodium hydroxide (caustic soda), potassium hydroxide (caustic potash), sodium carbonate (soda ash), and sodium silicate (water glass). They react with acids to form salts and have a swelling or dissolving effect on many organic materials.
Use in the textile industry
In the textile industry, alkalis are used in numerous wet finishing processes, including scouring and mercerizing of cotton as well as desizing and bleaching of gray fabrics. Strong alkalis such as sodium hydroxide increase fiber swellability, thereby improving the dyeability and luster of cellulosic fibers. In reactive dyeing, alkalis are added as fixing agents to initiate the chemical bond between the dye and the fiber.
Learn textile knowledge in context
You have just looked up a single technical term. In textil trainer, you learn how textile materials, processes, and contexts are connected.
The free learning platform teaches textile fundamentals step by step in interactive online courses. Each online course includes its own glossary with the most important terms of the respective topic. Across all courses, more than 600 textile terms with narrated explanations are available.
textil trainer is developed together with the Chair of Textile Technologies at Chemnitz University of Technology, chemmedia AG, and companies and educational institutions from the textile sector.