Mildew and mold are from the same family of organisms. The mildew fungus causes staining with an irregular shape. The appearance ranges from gray to black, but sometimes is yellow to red in color. It leaves a musty odor and sometimes causes fabric degradation. Mildew is most likely to develop on cellulose or protein fibers.
If the dye is not colorfast to any of the oxidizing bleaches, test for colorfastness with ammonia and detergent because this may improve the garment.
Moisture, and a lack of ventilation and light accelerate mildew growth. Therefore, items in plastic bags should be processed immediately to help prevent mildew growth.