Windows Glass Restoration Process
We Employ A Meticulous Method For Restoring Original Window Glass
We Safely Remove the Glass
Once the windows have been dismantled and the hardware has been removed, we remove the glass. This is called de-glazing because the glass can only be removed by also removing the glaze…which is sometimes as hard as rock! That’s why we use steam heat for this process. Steam softens the glaze, making it malleable enough to remove without damaging the glass.
When a more focused heat source is required, we use infrared heat guns. Unfortunately, there are many reasons glass can break in the remova process, especially if the glass is original, hence britte. But these are the safest methods to preserve as much original glass as possible.
But the job is not finished just because the glass has been removed. The residual glaze must also be removed from both the glass and the frame. Why must the rabbet be stripped down to bare wood? Because everyone knows not to place new wine in old skins or, in this case, new glaze on top of old glaze.
Once Removed, the Glass Must be Cleaned
We sometimes joke that the only procedure we charge for is glass cleaning. That’s because we clean the glass no fewer than three times. These artisans are removing the residual glaze and paint that is stuck around the perimeter of the glass in this first cleaning. The second cleaning comes after the sashes are reassembled and painted. The third cleaning happens just before we reinstall the sashes.
By the way, are you familiar with Murphy’s Law of Glass Cleaning?
“The smudge you see will be on the other side of the glass. But when you turn it over, you won’t see that smudge. You will, however, see another smudge…but it will be on the other side of the glass.”
The Frame is Primed
Before the glass is reinstalled, we prime the frame, including the rabbet into which the glass is set. Why bother priming an area that will never be seen? Because if the rabbet is not primed, the oil in the glaze soaks into the wood, thus shortening the life of the glaze.
Bedding the Glass
The sash is now ready for the glass to be re-installed. The first step is to “bed the glass.” First, a layer of glazing compound is pressed into the rabbet. The glass is then laid in place and pressed down so that excess glazing compound oozes out on the interior side of the sash. The glass is then pinned in place and the excess glaze on the interior side of the sash is removed, leaving a smooth edged gasket-like layer of glaze that seals the gap between the glass and the frame. This picture shows what the assemblage looks like when the glass has been properly bedded.
Did you ever stop to consider how amazing glass is? Here’s a pile of glass with a lamp shining light through it from the opposite end. And that other pile? That’s a pile of glass fragments we shaved off original glass that had been improperly sized and was too big for the openings. Yes, given skill and precision, glass can be shaved!
Preserving Original Glass
We do everything we can to preserve original, ‘wavy’ glass. But this old glass is brittle and, inevitably, pieces break. When the break is small, though, and is located near the edge of the glass, we offer the client the option of gluing it back together. In this instance, we were able to echo the line of the sash muntin, thus making it nearly invisible from a 3-5 foot distance.
Tinting the Glaze to Match the Interior Finish
Notice that the glaze used to bed the glass in the sash pictured above is tinted to match the color of the wood. When the interior side of the sash is to receive a natural finish, this glaze line on the interior side of the sash is visible. We tint the glaze so that it blends with the interior finish. Had we left this glaze in its natural putty color, there would have been an unsightly white line around the interior perimeter of the sash where the glass is housed. Tinting the glaze to match the color of the stained wood on the interior side makes the glaze line disappear. The clean line this procedure enables causes the sash to “snap to attention” with an appearance that is both neat and “sharp.”
Having bedded the glass and pinned it with glazing points, the sashes are ready to be re-glazed.
Painting the Sash
Once the frame has been primed and the glass has been bedded, fixed with glazing points, and glazed, the sashes need to sit for at least a week to allow the glaze to cure. Then, when we apply the finish coats of paint, we are careful to paint a 1/32″ beyond the glaze line on the exterior, and the bedded line on the interior. First the rabbet is primed. Then the glass is beded on the interior side and glazed on the expterior side. Once cured, the glaze is then sealed in paint. This is the way to ensure the glaze will not dry out prematurely and the glass will have been sealed tight against the infiltration of air and moisture.
Here is what one client said about the level of detail to which we attend:
“[Oak Brother’s] attention to detail and precision in their workmanship is more than we were hoping for. For example, they hand applied the glazing compound and painted it and it precisely matches the reveal of the wood on the inside. The paint overlaps the glazing by about 1/32″ of the glaze and is consistent all around. It’s a remarkable level of precision for work done by hand.”
-David McCammond Watts