Starbrite Mildew Stain Remover, gallon. Mildew Stain Remover quickly removes unsightly mildew stains from fiberglass, vinyl, plastic or painted surfaces. It begins working on contact. The special buffered formula will not harm vinyl upholstery or threads. It is a much safer alternative to using bleach, and can also be used around the home or in RVs wherever mildew stains are a problem.