Curved Sash Restoration

[phil]

hello eric in Vermont....


another option is to glue the glass...
....jade

maybe one of these?
https://www.permatex.com/products/speci ... epair-kit/

[ericinvt]

Thank you all and sorry for the confusion. These are curved, not arched sashes that I am inquiring about. We have a total of 10 windows that are curved, so 20 curved sashes to restore. Thankfully we only have one broken pane, so far.
Phil, thank you for the link to that product. Has anyone on here used it? We have a very large window in the front parlor made of some of the thickest glass I've ever seen. Unfortunately it has a couple of holes in it, probably from a BB gun. I'd like to keep the glass but repair, if possible and have been looking at these repair kits.

[phil]

Those kits are intended for cracked windshields. Windshields are two layers with a plastic film between so a bit different from house windows. Car side windows are tempered so they shatter if they break , they dont' crack.

A car window place might use a vacuum pump, but I think the general idea is you use vacuum to void any air from the crack and then the crack fills with glue and becomes invisible. I was thinking maybe you could support the pieces in correct relation by clamping it to some bendable plywood or maybe rigid insulation foam board or something to keep the pieces in relationship.

I would suggest watching some Utube videos on car windshield crack repairs and if you do you will see there are some other products that are similar to the permatex one. they come with a tool that creates and holds vacuum near the crack, the kits use a little tool for this so you don't need a vacuum pump but maybe a vacuum pump could work even better? I think you really only get one try, maybe a local glass shop that also does car windows could do it for you ?

Phil

[heartwood]

we use resins from this company: https://www.deltakits.com/shop/windshie ... ucts/resin
I use the magni-bond and a UV lamp to glue glass...I don't recall which product it is that fills voids, you may want to call the company...if you have curved/bent glass with a bb hole, it is cost effective to fill the void with the resin, razor off the excess and call it a day...

clean glass well (no ammonia)...I use denatured alcohol to clean the area to be glued...place the two pieces on a flat surface (unless you're gluing crown glass!!) and use blue painters tape to secure the two together with a nice snug fit...turn over the glass, add a couple of drops of resin (watch it bleed through and darken the tape between the two pieces), then apply clear cellophane over the crack...the resin works best in the absence of air, hence the cellophane...I use the uv lamp but you (historic district master gluing homeowner extraordinaires) can use uv from the sun--maybe an hour or so....for the bb hole, fill the void so the resin is 'proud' and set the glass in the sun...use a new single edge blade to slice off extra...

typically, homeowners don't want to see a glued crack or a resin filled void...it's our museum quality buildings that get that treatment...curved/bent glass is super expensive...

and there you have it from my corner of rural Massachusetts.....
...jade

[phil]

when light enters glass it refracts, or changes direction as it goes into the glass and then that direction is changed back to original as it leaves. this is because light travels at a different speed through air than it does through glass.

so you see the crack because of the difference in the properties, as it hits the cracked area it doesn't continue in a straight path , but scatters due to the irregular edges. If you fill it with the glue , it is closer to the density of the glass so it hides the crack.

often vacuum is used when mold making or for laminating wood with epoxy, It pulls the liquid into the pores. Also if there is a bubble , the vacuum makes the bubble decrease in size. Once the glue is hard it can't re-expand. Jade has more experience with doing the repairs, but that just explains a little about the physics of what is happening. I don't know if you need vacuum for the BB hole.. It occurred to me that if you didn't get it hot and you wanted to use sunlight then you could simply use a magnifying glass to reduce the time a little, just dont' concentrate it so much that the heat causes an issue.

[Gothichome]

Ericinvt, I think Jade advice is the way to go on your B.B. holes. With the cost of a large heavy piece of curved glass it is the perfect solution.

[Mick_VT]

Ericinvt, I think Jade advice is the way to go on your B.B. holes. With the cost of a large heavy piece of curved glass it is the perfect solution.

This....

the preservationist in me says it's better to have the original in a repaired state than a repro in the perfect state. Depending on the state of course!

If funds allow I might consider getting a pro (such as Jade) to do the restoration of all the bowed sashes , as the likelihood of more damaged panes would be greatly reduced

[Gothichome]

Good point Mick. My leanings are to repaired originals. Depending on condition as you mentioned. I would be very Leary about doing curved glass windows myself just cringe at the thought of cracking a salvageable sheet of glass and the cost of replacement. I would have no fear of restoring the glass in place, just going that extra step of removing the glass.
Now, Jade, Sashguy and a few others here would have the confidence to do curved glass, but I suspect even with thier skills braking a pane of glass is always a possibility.

[heartwood]

oh yes, breaking curved glass is a good possibility....I worked on three sets of curved sash last summer...glass was 1/4" thick...one pane broke in the steamer, highly unusually and rather costly...as I recall, about $400....two other panes had already broken over the years so it end up being about $1,200 for three panes of glass!!

...jade