Windows are an expensive investment. If you see hard-water or calcium deposits building on the surface of the glass, call us as soon as possible. It is important to remove hard-water minerals on the surface of the glass before Stage 2 corrosion takes place. When it reaches this stage, it is nearly impossible to remediate. We have rubbing compounds for minor build-up and several special acids for removing more heavily corroded window panes. It is important that your window cleaning technician knows how to identify, remove, and protect against further corrosion so that your glass shines clear for years to come.