I am about to begin restoring some 50 year old wood windows in need of a reglaze. Caulk in large amounts has also been used around the glass where glaze should have been used. The caulk is rock hard and a scraper just won’t remove it without damaging the glass. Is a chemical available to help the removal of the caulk and old glaze?
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Replies
There's several ways to remove old caulk/putty.
You can try warming it up with a heat gun. Be careful about getting the glass too hot and cracking it.
There's a gizmo that you chuck into an electric drill that will route out the out putty. It works pretty well.
You can use a sharp chisel and GENTLY tap down where the wood meets the putty. It'll usually come out fairly easily. You'll probably have to sharpen the chisel a few times.
I've never tried any chemicals to soften the glazing, but I would imagine it would work, too.
Use a heat gun, with a metal sheet (old license plate?) to heat shield the glass. Loosen the caulk / putty and lift it out with a 1" putty knife. Utility knife can help, too. Take it slow; get ALL of the putty out; razor clean the glass.
The best thing is to then remove the glass sprigs, then the glass; clean the rabbet and the glass perfectly, prime the glass seat, reset the glass in thin smear of 50-yr caulk, re-sprig, then putty as normal. I use DAP only; put in the microwave first. Wait several weeks before you paint the putty, goofy as that sounds - the paint will hold better.
Don't try one of the Prazi things - I've got one; it's useless.
Forrest - house full of old windows
I think I've seen a power tool for removing old glazing compound. Is that the Prazi thing? Or is there something else?
Prazi does make one, just be sure you use a high rpm drill.
In consideration for the NEXT person who has to reglaze the windows, you should stick to glazing compound to bed the glass in. I've heard that Sherwin-Williams has one called '66' but I've never tried it myself.
Yeah, that's probably right. I just find it hard to make a thin smear of putty - caulk is easier. Putty bedding goobs out big globs on the interior (finished wood side).
Forrest
Have you tried rolling the putty into a thin rope? I usually do several pieces rather than try one long piece. Of course it still comes out on the inside, but I just slice it away.
...with a metal sheet (old license plate?) to heat shield the glass.
drywall mud tools work well as shields - they come in various widths -
to OP: after you have the sash all cleaned and bare, paint all surfaces with boiled linseed oil, let it set for for a day or two, wipe, and then proceed with the restoration -
this is the traditional seal for window sash and will make your reglaze stay in place -
a '7 in one' or '9 in one' tool (glorified putty knife with point on one side) sharpened like a chisel is a valuable tool for this task -
also I have several (good quality) putty knifes with blades of various stiffnesses sharpened to a knife edge - different putty situations seem to respond to different tools -
it's a big fussy job, but rewarding -
"there's enough for everyone"
It's usually a good idea to mix the boiled linseed oil with turpentine, about 50/50 mix. It increases the absorbtion into the wood and dries faster. And if you do this, be sure you use a primer compatible with linseed oil and turpentine, basically an oil based primer. I brush it on with a natural bristle brush, wait 10 minutes or so, then wipe down with a cloth. Then I brush on again. So people say just priming is sufficient. The idea is to keep the wood from drawing all of the moisture out of the putty.
I use oil primer to prep the sash. Is boiled linseed oil as good a prep as oil based primer?
I oil and then primer - make sure it's 'boiled linseed oil' -
Brians point about cutting the oil is valid -
"there's enough for everyone"
google around for a web site about window restoration and steam.
It wasn't just a DIY page but a pretty serious restoration web site. They rig up a steam generator and the heat works like a heat gun but much less chance of breaking the glass.
I'm sure they have more useful info for your project as well.
splat
As a bonus, steam will also strip the paint, depending on just how you use it. Of course it raises the grain too.
I quit using heat to soften the putty in my 160 year old sashes after a pane cracked.
I wouldn't worry too much about cracking 50 year old glass. It's more solid. If you do break any, it is inexpensive to replace.
Ed, if you no longer use heat, what do you use? I use a torch and a heat shield; with the torch I can direct the heat pretty accurately, but I've still cracked one or two 160-year-old panes.
Also, I'd be interested in your home restoration (always great to hear from someone who actually wants to keep their 1840 windows in place). Any chance you could post some photos in the Photo Gallery here?
Allen
I have a tool that I use occasionally on really stubborn pieces. It is basically a straight soldering iron with a razor blade on the end. Pretty slow, but it does work on stubborn pieces.I'm not sure if they are still available or not. But I bet the creative among us (not me) could make one.
Ed, if you no longer use heat, what do you use?
Also, I'd be interested in your home restoration .... photos
Allen -
I now scrape out the loose putty with a putty knife or even razor blade. Only the loose parts get removed, so most everything stays. It doesn't look as precise or crisp as what I had in mind earlier. That was back when I intended to do a perfectionist level of restoration here.
I still have an eye for precision, but I don't practice it in this house. You wouldn't believe what a journey this purchase has turned into.
I don't have photos of an architectural sort for you. If I ever do have any, they will show a basic rural 1840's frame house. If I remember correctly, you are the guy with a very refined Greek Revival house.
Thanks for your interest. It actually serves as a motivator.
Ed
Fight Perfectionist Tendencies in Preservation Projects. Preserve Either Your House or Your Sanity.
Ed, dunno if I'd describe my house as "refined," as it's a relatively simple rural farm house. It does have some nice Greek Revival details, so you're probably recalling the correct house. But I am very interested in vernacular (and particularly "simple") houses of the period, 1790 to 1845.
Allen
Mine is one of the relatively simple farmhouses from the tail end of that period, so you would probably like it. It has been altered, but it has retained more of its interior form than most.
If I get any photos taken this Fall (which means getting some work done first) I'll post them.
The tagline was developed in my first response. It said that things that I did not want to try and explain in the post.
Fight Perfectionist Tendencies in Preservation Projects. Preserve Either Your House or Your Sanity.
Ed, I just read your tagline. Great!
I with you in regards to just taking out loose putty, and "patching in." But when I extract old panes from salvaged sash, I have to get ALL the putty out.
Allen
i'm doing the same in my 60 year old house. i tried to remove and reuse the glass in the first window, but discovered that it take forever and break 3/4 the panes anyway. now i cut an X with a glass cutter and tap it from the inside. it comes out in 4 pieces and brings out most of the glazing compound with it. on a 6 over 6, glass costs me less than $30 per window, and saves my sanity.
after stripping, sanding and priming, i bed the glass in a very thin bed of silicone and finish with dap 33
Doesn't old putty contain lead?
I don't think the putty contains lead, but the paint covering it probably does.