glass removal problem

[Kevin Jenness]

I agreed to replace the scratched glass in a wood storm door panel for an old client, but have run into difficulty. The glass is very securely adhered to a rabbeted red cedar frame with what I suspect is polyurethane caulk. I expected silicone bedding which I have been able to dislodge in the past by driving in stacked single edge razor blades, but this stuff is not giving in to persuasion and I fear the wood frame will break. The glass is about 3/16" x 22" x 66" which leads me to believe it is laminated rather than tempered (I would expect tempered to be 1/8" thick). If it were tempered it could be broken into rubble and probably removed in fragments from the frame, but I am not at all sure about making that happen with laminated glass.

The scratch is minor in my opinion but the clients are house proud. I am tempted to tell them I can't do the work and their best bet is to live with it. I am pretty sure if they take it to a typical glass shop they will wind up destroying the frame. Any advice?

[Jerry Bruette]

How big is the scratch? Could a auto glass shop be any help, maybe buff it out?

[Kevin Jenness]

Good suggestion, I will look into polishing.

edit: I got a thumbs down from a couple of glass companies saying it is a high risk/reward. I may have to replace the wood frame too if the glass won't come out clean.

[Maurice Mcmurry]

I will try to find my hot knife and post a picture. It works for all of the caulks, glues, and putty I have come across. It even helps with removing silicone. It is not fast

[Robert Hayward]

Have you considered cutting the caulk with a wire. Like the auto glass people use to take out an old windshield. Cuts urethane caulk like the proverbial hot knife/butter. The one pictured is from Amazon.

[Kevin Jenness]

Thanks for the suggestions. I wound up using my oscillating saw, took about 1/2 hour. I don't know how a wire would work in a rabbet; a very thin hot knife might have done the trick in this situation. I rarely use the Fein tool or Sawzall but when I need one I really need it.

[Bradley Gray]

When I was in high school I worked at the local lumber/ hardware and was in charge of sash repair. We had an L shaped device about 1ft x 6 inches with a ni-chrome coil and power cord for heating putty for removal. Worked great.

[Cameron Wood]

I was going to say hot knife as well.

I have clients that wanted me to replace their seal-failed glass panes in custom made wood windows. A bunch of 6 & 9 lite upper sashes and more. Dozens, with unknown bedding and wood stops.

With persistence, I was able to avoid the project.

[Kevin Jenness]

Avoidance would have been the better choice. I will set the new pane in closed cell foam glazing tape.

[Tom M King]

I bed glass in cheap latex caulk. It’s not really exposed to air or light so it’s just a cushion and seal. It’s most important that it’s easy to remove when the time comes. Strong bond is not important and actually more of an aggravation than an asset. It really just forms a gasket.

I use a sharp chisel to trim it off after it has set up. Slice it the other way first with something thin and sharp or you can pull it out of place. This was first sliced with a single edge razor blade next to the wood. In this particular case with painted interior on these 1850 sash, the finish coat covers this caulking and touches the glass to form a seal.

[Kevin Jenness]

Thanks, Tom.

[Paul F Franklin]

I bed glass in cheap latex caulk. It’s not really exposed to air or light so it’s just a cushion and seal. It’s most important that it’s easy to remove when the time comes. Strong bond is not important and actually more of an aggravation than an asset. It really just forms a gasket.

I use a sharp chisel to trim it off after it has set up. Slice it the other way first with something thin and sharp of you can pull it out of place. This was first sliced with a single edge razor blade next to the wood. In this particular case with painted interior on these 1850 sash, the finish coat covers this caulking and touches the glass to form a seal.

Use care when cutting against glass so you don't score the glass, even a little. This can form a weak spot that will turn into a crack if the glass ever gets a sharp bump or tap. DAMHIKT. I (now!) use a plastic razor blade for trimming against glass, but it probably wouldn't cut through caulk.

[Tom M King]

You don't have to push very hard with either to trim the cheap caulk. I've done some number of hundreds of window panes and never broken one when trimming it. I expect you'd have to push pretty hard with a steel edge to score glass.

[Tom M King]

With single pane glass, if the sash or door is painted on the inside I use exterior paint on the interior side. Water will condense on the glass at some point and interior paint will buckle when it runs down. I've never come across painted on the interior sash with single pane glass that didn't have paint issues on the horizontal pieces inside. Never had to redo a sash with exterior paint on the inside.