Mending Broken Glass

Remove old panes & putty, cut & clean glass, putty & paint.
johnleeke
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Mending Broken Glass

Postby johnleeke » Fri Mar 15, 2019 6:17 pm

It is possible to glue the edges of broken window pane glass back together. It takes a special adhesive that has the same refractive index as glass, so that the glued line does not show.

Try LocTite Glass Glue. Readily available, low cost, refractive index similar to most window glass so joint is not so apparent, quick cure time, actually works.

http://www.loctiteproducts.com/p/sg_gla ... s-Glue.htm

I've used it by setting the two pieces of glass in the bedding putty with the broken joint slightly open, then applying the glue, then moving the two pieces together, adjusting the two pieces of glass optically to get them in the same plane, letting the glue set for 20 minutes, then finishing the glazing. First use in place for about 20 years, still holding up.

Another glass adhesive is Hxtal, available at www.talasonline.com which is a conservators supply house. It is somewhat tricky to use as you have to be accurate with the part mixture (mixed by gram weight). so it takes a special scale to weight that out. It also takes a fair amount of time to set up. You will need the release tape also. It isn't cheap but with the small amount used to repair glass, one bottle will last a lifetime.

Another product from Delta Kits is MagniBond Resin:
http://www.deltakits.com/
where they specialize in auto windshield repairs The 1/2 ounce bottle of adhesive costs about $35. It cures by UV light, either from a special UV lamp, or by setting the repaired glass in the sun for curing.

If you are interested in more on this method, post a message below and I'll provide step-by-step instructions with photos.

Hester555
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Joined: Thu Aug 15, 2019 6:08 pm
Interests: Restoring my wood windows, cottage about 110 years old, in seaside town in California.

Re: Mending Broken Glass

Postby Hester555 » Thu Aug 15, 2019 7:49 pm

I have a piece of antique lead wavy glass, beautiful, that has cracked along the corner, about a 8 in long triangular piece in a 48x32 in fixed window. My guess is that since it is fixed, that I will just have to put a new piece of glass in it, not glue it. The glazing is intact and this piece has been stable. But my partner really wants to have it repaired, since it is at the front of the house and is in our view every day. After reading this post, I wondered if you think I can repair it by removing the broken triangle in the corner and then gluing it? It will be in the vertical position.

There is almost no source of old glass here in Santa Cruz. Our one resource, that recycled building supplies, had older sash windows closed about 5 years ago. The chance that I can get a piece of old glass this big is really not possible. There is reproduction glass, but it is no where near the beauty of this one.
What do you think?

johnleeke
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Re: Mending Broken Glass

Postby johnleeke » Tue Aug 20, 2019 3:07 pm

8" is longer than I have done, but it should be possible.
It's possible that it can be mended leaving both pieces right in place, if the two pieces of glass are still aligned in the same plane, and close together. It may not work well if there is anything in the crack, like residue from past window cleaning. (do not wash the glass, because the cleaning fluid will soak into the crack, possibly preventing the adhesive from working.

Are the pieces well aligned?
Does the inside of the crack look clean?
Have you ever washed this window? If so, what did you use for cleaning fluid?

If the crack is not clean inside, then one or both glass pieces would have to be removed from the sash, then cleaned, then glued together. Then the mended pane glazed back into the sash.


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