Mold and mildew are fungi, and the stains we associate with them, typically pink, yellow, purple, or black, are by products of their digestive process. The compounds they produce can diffuse into a textile and discolor it in a way that can’t be removed simply by washing it. Fungal spores will grow in any warm, moist location where they can find a food source. Keeping a fabric clean and removing any mold or mildew with diluted household bleach (only for bleach cleanable fabrics and only in the recommended ratio) will reduce the number of spores and food sources available to cause problems. Choosing designs that allow water to run off of a surface or escape from inside of a cushion will also help prevent mold and mildew from growing.

A mildew resistant fabric has not necessarily undergone any specific chemical treatments. Unlike natural cellulose and protein fibers, petroleum-based products (polyester, nylon, polyethylene, and polypropylene, for example) create environments that do not encourage the growth of mold, mildew, or bacteria. Although the fibers themselves are resistant to microbial growth, if they are allowed to collect dirt, grime, and moisture, bacteria and mold will be able to grow.

Fabrics treated with an antibacterial finish offer additional protection against bacteria and mold. Unlike synthetic fibers’ natural resistance to microbial growth, these chemical finishes are designed to actively inhibit growth or eliminate bacteria or fungi. Some of Brentano’s polyurethane faux leathers include an antibacterial finish that is added to the polyurethane compound before it is poured. The active component of the treatment is silver ions which disrupt bacterial internal functions. This form of antibacterial finish is widely recognized as one of the least harmful for human health.