What’s known as pink stain is a common problem on light colored vinyl. Marine fabricators know exactly what pink stain looks like on cushions and other applications, but the problem also occurs in flooring, bedding and other vinyl surfaces.
Thomas Robitaille, global technical marketing lead at Lonza Inc., presented an overview of pink staining Oct. 19 at the IFAI 2016 Expo in Charlotte, N.C. He says, “Everything that lives eats, and everything that eats excretes.” The bacteria that causes pink staining—streptoverticillium reticulum—excretes dye that moves throughout the vinyl.
That dye cannot be cleaned from the vinyl once it’s there, explains Robitaille. The bacteria that causes pink stain feeds on the plasticizers that impart flexibility to PVC. In addition, the seams and foam padding in marine cushions are great breeding grounds for the bacteria, because of their potential to trap moisture.
Robitaille adds, “If there’s no water, there’s no growth.” However, in the wet environments where marine fabrics are used, water is found in abundance. Preventing bacteria from breeding in vinyl depends on adding antimicrobials to the materials. Robitaille says arsenic has been a historically used antimicrobial, but it can no longer be used in Europe and is being phased out in Canada. Eventually, arsenic will not be used in the U.S. either.
Zink Pyrithione (ZPT), the active ingredient found in Head and Shoulders shampoo, was developed by Lonza and is extremely effective as an antimicrobial in vinyl textiles, Robitaille says. ZPT prevents the growth of bacteria, mold, mildew and fungi. Robitaille emphasizes, however, that pink stain is not caused by fungi; pink stain is always caused by bacteria.