One of the most difficult stains to identify and remove are yellow stains that are of an unknown origin. These stains may be visible prior to the dry cleaning or wet cleaning processes or may appear after processing. It is often difficult to explain to the customer the cause of these discolorations.

Yellow stains may be caused by:

1.      Grease or oil stains that have oxidized
2.      Oxidized tannin stains
3.      Oxidized protein stains (oxidized protein stains are usually yellow or brown in color)
4.      Staining substances that have chemically degenerated the fluorescent dyes (optical brighteners) within the garment

The identification of the source of a yellow stain can be difficult. Most yellow stains can be identified by inspecting the stain itself and its location.

Oxidized Grease Or Oil Stains. This type of staining substance can appear anywhere within a garment. This type of yellow stain can often be identified by its color (usually yellow in color). The outer portion of the stain will usually have linear jagged edges or may be cross shaped. These stains can be removed by treating them on the “dryside” (OTPR or POG and amyl acetate)

Oxidized Tannin Stains.Oxidized tannin stains are yellow or light brown in color. .When these stains oxidize, they will develop a darker smooth outer ring. Oxidized tannin stains can be removed on the board by following the tannin spotting procedure followed by 3% hydrogen peroxide or sodium perborate

Oxidized Protein Stains.In most cases, this type of yellow stain is the result of perspiration that has discolored the underarm areas of a garment. Yellow perspiration stains can sometimes be removed on the board by using the protein stain procedure (including 3% hydrogen peroxide). Unfortunately, since the acids and chloride salts in perspiration can chemically degenerate the fluorescent dyes within the fabric, these yellow underarm discolorations may be impossible to correct.