At The Kroger Company’s regional office building in Atlanta, which was recently purchased after years of leasing, employees remarked that they could not see out of the windows because they had become so stained.
Buildings like Kroger’s with precast concrete facades are inherently susceptible to window staining when windows are installed flush with the precast concrete façade, allowing rainwater to wash across the windows and deposit minerals from the precast onto the glass surfaces. These minerals embed themselves within the pores of the glass, causing staining that cannot be removed without more aggressive techniques. Removing these tenacious stains without creating scratches to the glass surface or causing etching (due to improper use of hot acids) is complicated by many factors. These factors include direct sunlight, temperature of the glass surface, humidity levels, and trained workers in this craft. Every building, and often each elevation of a building, may require unique approaches to glass restoration.
After performing a test demonstration for client approval, Valcourt’s crew developed a technique that would remove the window stains without either etching or scratching the glass surfaces. The technique first involved determining how to remove the hardened, outermost crystals of the mineral stain. The next step involved a buffing process to eliminate the portion of the stain that embedded itself into the pores of the glass. A minimally abrasive, non-acidic compound was used with an electric buffing wheel, whose speed was closely monitored. Workers must be trained and experienced in using this specialized procedure, because the glass surfaces can be adversely affected by the rate at which the wheel spins.
Valcourt was successful in restoring the windows to the same level of optical clarity as if they were new again. The Kroger client is extremely pleased with the dramatic improvement to the glass and how it greatly improved the overall curb appeal of the property; employees are happy that they can now see out of the windows. Valcourt subsequently developed a customized maintenance program for The Kroger Building to help mitigate the reoccurrence of window stains on the glass.