Aluminum hydroxide is used in the dyeing industry as a mordant. A mordant is a substance that helps dyes stick to fabrics by forming a complex with the dye that attaches to the fabric. 

In dyeing, salt's primary function is to enhance dye absorption and fixation, while a mordant's role is to create a chemical bond between the dye and the fiber, improving colourfastness and potentially altering the final shade. Salts often act as a dyeing promoter, increasing dye exhaustion from the dye bath. Mordants, on the other hand, are typically metallic salts or other substances that form a stable complex with both the dye and the fiber, ensuring the color remains vibrant and stable.