The Label on the 303 Fabric Guard warns not to use it on “synthetic suede”. Why Not?
303 Fabric Guard imparts enduring water repellency to all natural leathers – upholstery, clothing and footwear (including deerskin and suede). 303 Fabric Guard protects against soiling & staining as well as helps the leather be water resistant. 303 Fabric Guard should not be used on synthetic suede, not because of the product itself, but because of the carrier, Odorless Mineral Spirits (OMS), a mild solvent. As a general rule, even mild solvents should not be applied to rubbers & plastics. Synthetic suede is a plastic.