Whether it’s steel windows or wood windows removing glazing putty is one of the more frustrating things to do in my opinion. How hard the work is depends on a lot of factors like how old the putty is and what type putty was used. There are a few tricks to remove glazing putty without breaking the glass that I can show you.
Mainly it comes down to being patient and careful. No matter which technique you use remember that you are working with very thin glass that doesn’t require much force to break.
Always keep yourself safe when working around glass by wearing safety glasses and gloves. You never know when you may have unexpected breakage.
How To Prevent Broken Glass
Before we get into putty removal techniques I want to give you a couple good tips on how to protect that beautiful wavy glass. After all that’s what we’re after here right?
1. Clean Corners – Make sure you clean the corners free of all the putty you can before trying to remove the glass. This is one of the most fragile areas and it’s the easiest to forget a little chunk of putty. Clean everything out of the corners very well before trying removal of the glass.
2. Stray Glazing Points – There is almost always an extra glazing point that you’ll miss and it often spells doom for your glass. Double check that you have removed ALL the glazing points and then check again because there is always that one hidden one lurking.
The Chisel & Scraper
I’ve tried probably more than a dozen different tools and techniques to remove glazing putty, but it often comes back to the old standard. It’s not sexy or exciting or new, but for removing anything from cement putty to caulk a good chisel can work wonders. And it’s super cheap and portable!
Like in the picture above I like to run the chisel along the joint of the putty and the glass first. It usually takes a few passes and with each successive pass you’ll dig a little further between the putty and the glass breaking that seal. Don’t try to get it in one pass or you will likely break the glass. Take your time and work it a little bit at a time.
Once you’ve got the putty and glass separated then move to the joint between the putty and the wood. Be extra careful here to not gouge the wood. Other than breaking glass this is the most common issue with using a sharp chisel on a soft wood sash. Again go slow and work methodically. Eventually the putty will begin chipping or peeling off in chunks.
After the chisel has done it’s work I use a ProScraper to scrape the rabbets clean of any excess putty so that the glass will come out smoothly and not get caught up on any trouble areas.
This is what I use in my shop to remove glazing putty. It’s fast, clean and very effective. Not to mention it keeps the dust down and that helps us work Lead Safe. You can use any standard clothes steamer and do spot work or you can build a steam box (learn how here) pretty inexpensively. If you plan to do a lot of windows a steam box is absolutely the way to go. For one or two windows the chisel and scraper is the best.
After an hour in the steamer the glazing putty is softened up and comes off much easier. It also comes with the added bonus of helping removing the paint in preparation for restoration. Check out my video of how steam glazing removal works.
It’s so much more than plain red, it’s…INFRAred! Seriously though, infrared heat is a great way to remove glazing putty. Like steam heat it helps to soften the putty and make it more pliable so that you can scrape it off with something as simple as a 5-in-1 or putty knife.
I place aluminum step flashing over the glass to protect it from the heat otherwise you will end up with broken glass due to the intense heat. Just a few pieces that you can move from one section to another is enough to protect your glass.
When using any kind of infrared or even regular heat guns be careful to keep moving. Don’t leave the heater in any one location for too long or you may end up burning the wood and paint. It doesn’t take much heat to soften the putty, so start with short 10-20 second bursts and gradually lengthen it out if necessary.
What About Cement Putty?
Cement putty is a real thing and it is more common on steel windows than wood windows, but it can show up anywhere. There are some putties that once fully cured are as hard as a rock and are completely immune to steam, infrared, chemicals, or anything else.
They are annoying and unpredictable as to where you will find them, but when you do there is only one thing to do and that is to break out the chisel. It dulls chisels and is exactly like the name implies, hard as cement, but it will come out and it can be restored with new putty that won’t turn to stone. Good luck!