Starch, etherified cellulose, polyvinyl alcohol, and other sizes must be removed from fabrics prior to dyeing. Because starches are carbohydrate compounds that become insoluble in water after curing, they are removable only by desizing processes based on enzymes or other chemical agents. Polyvinyl alcohol and modified cellulose starches are water soluble and therefore easier to remove. However, they are costlier to use than starch. Basic dyes are colorants with high brilliance but moderate to poor fastness properties on cellulose and animal fibers. Dyeing cellulosic fibers with basic dyes requires the use of a mordant. Basic dyes are most suitable for dyeing acrylic fibers. Acid dyes are water soluble dyes applied from an acid medium. Reactive dyes are water soluble dyes that produce brilliant shades with very good lightfastness properties used primarily for dyeing cellulosic, nylon, and wool fibers.