Perspiration stains usually appear as yellow stains in the underarms and on the back, and may have a noticeable odor. Perspiration is composed of mainly water, but it also contains other substances, such as chloride salts, amino acids, and ammonium compounds. These substances can oxidize with the heat of the drying cycle or the heat of pressing, causing the stains to turn yellow. Perspiration begins as acidic substance but later decomposes to an alkaline condition. Silk is very susceptible to becoming discolored by alkaline substances.

Manufacturers will often add coatings to the reverse side or surface of fabrics to make them more water repellent, wind resistant, and insulated. These coatings, as well as adhesives that are used to apply the coatings, may be adversely affected by drycleaning solvent. Outerwear fabrics containing polyurethane coatings are especially susceptible to damage.

After the item has been drycleaned a few times, the coating may begin to separate from the shell fabric, resulting in a darker appearance in the separated area. The garment may also take on a cracked appearance.
 

Q: What can you tell customers about removing candle wax from a linen tablecloth?