Crystal Clear 550 Glass Clearing agent is designed to dissolve alkaline residue stains, iridescence surface stains and stage 1 corrosion on uncoated, clear, and float-glass surfaces. Crystal Clear 550 cannot correct stage II corrosion and may visually expose more of the existing corrosion. Crystal Clear 550 is effective on most types of building glass and, when used properly, will make windows sparkling clean and optically clear as new. Always check glass, both inside and out, for potential damage before clearing each window.