BIO-DEX PWB04 1 gal Bottle PLASTER White 'N Brite when used as directed eliminates acid fumes, thickens the acid/water solution for better "cling" to pool plaster without etching of the surface, leaving the plaster smooth and beautifully white. Colored surfaces are left clean and free of scale and stains. PLASTER White 'N Brite is an acid wash additive that thickens acid for non-streaking application while eliminating fumes and etching problems associated with acid alone.