| Wanamaker Restoration

“The house we are buying has some windows that are stained on the outside with what looks to be a fine spray of white.  I”m not sure if it’s paint or what it is.  Anyway, it is the original glass and how should I go about cleaning it?”

Amanda

Hi again Amanda, and thanks for the question.

Well the general approach to cleaning or restoring anything is to begin with the “gentlest means possible” what that means is basically start with warm water and progress towards various solvents or solutions that may have a stronger impact on the surface you are working on, in this case glass.

With glass we have a little bit of wiggle room because glass is a very hard and impermeable surface to begin with.That being said you should make sure that there is not any coating or protective film applied to your windows, either inside or out. Low E films are sometimes applied to the interior of old windows to help reduce the effects of sunlight on interior furnishings and help with energy efficiency. These coatings can be easily damaged with solvents or razor blades when cleaning the windows.

If your windows don’t have such a treatment and they are original glass then you should start with warm water and a mild detergent. That will clean most contaminants from the glass surface and then you can move on to a more aggressive cleanser if need be. You may also want to try using a razor blade at this stage, start in a corner to see if there is any damage to the glass (there shouldn’t be unless there is a special coating on the glass) if not then keeping the glass wet with warm/hot water and scraping the entire surface should clean off any surface contaminates.

If warm water isn’t softening up the “white spray” then moving on to denatured alcohol may help. denatured alcohol is a good solvent for loosening up both shellac based paints and water based/latex paints. If the discoloration is persistent then you may want to try a stronger solvent such as lacquer thinner or acetone. be very careful with these solvents and always work in a well ventilated area to avoid prolonged overexposure to any fumes.

One of these combination’s should do the trick. Always follow up a cleaning with any solvent with a secondary cleaning, using warm water and detergent, and dispose of any rags or paper towels after they have been hung out to dry thoroughly.

In preservation, conservation,or restoration the tenet is always start with the gentlest means possible and work cautiously towards more aggressive techniques. Tackling any project with this approach will minimize the potential for damage to historic materials.

Good luck and have fun,

Ron