I am currently writing a free newsletter which focuses on the technology of window glass preservation, maintenance, and restoration. Many billions of dollars in window glass has been wasted by what has been called glass on glass deposits. The silicates in the concrete exterior fascade of high rise structures has been broken down by acid rain over the years. Rain is absorbed into the micropores of the concrete, breaks down the builder matrix, and leaches out the silicates. Which are then deposited via rain drops that dry in the hot sun when the rain stops. These silicate deposits being based on a silicon chemistry are very much like glass itself. Glass is based on a silicate silica matrix as we all know. Therefore the only acids that will react with such hard water spots/deposits will also chemically attack glass itself. As a result of this many companies have inadvertantly used acids such as hydrofluoric, sulfuric, and ammoniumbifluoride to remove these spots. In so doing they have done irreparable damage to many buildings from coast to coast. Windows have been rippled, orange pealed, and frosted. Not to mentio the degradation that has been unknowingly done to many of the first surface hard coats like PPGs Solar Cool. The only safe method for restoration of surfaces that have been damaged by glass on glass deposits is a polishing system. If this kind of information is of interest to anyone just let me know. I will write more about it on this forum, and include your email on my list.
Henry Grover Jr.
Glass Tech Services