My staff and I conduct homeowner workshops in conjunction with the Preservation Alliance of Philadelphia 8 evenings a year. When the topic turns to window repair, we always know that there are going to be a dozen questions concerning the removal of old, hardened putty. I know that there are a number of techniques including steam, chemical, heat gun (careful!) Fein multi-master reciprocating blades, and everyones favorite, slowly picking away with a cheap chisel and a utility knife. About a dozen years ago I stumbled upon a 50's era electric putty softener at an antique tool auction. I actually wasn't certain what it was and the list of auction lots wasn't that helpful. It is an "L" shaped tool with a heating coil tucked into a "V" shaped recess around 2 sides. When it was plugged in (no switch) the coils glowed red. You can set it directly on the glass and slide it up against the hardened putty. Within 30 seconds the putty was as soft as clay and easy to scrape away. I was hooked. Since then I've purchased a modern version from CR Laurence which is a bit larger and heats on 3 sides, and I've used it frequently. I'm curious to know if anyone else has any secret tools or techniques for removing old glazing. Incidentally, the putty softener greatly lessens the chance of differentially heating the glass and cracking it, but it doesn't eliminate it. Used with care it can make a difficult task much easier to take.
I came upon a tip for removing glazing putty in an old copy of American Carpenter and Builder- it involved coating the putty with gasoline and then setting it on fire! It might work, but I don't think I'd recommend it...
I have used a Makita hot air gut with their standard "flair" nozzle, to which I add a sheet metal baffle that keeps the hot air off the glass. This cut down my glass breakage rate from 20% to 12%. (switching to steam deglazing cut my glass breakage rate to less than 3%)
Milwaukee tools sells a Heat Gun kit that includes a narrow nozzle attachment. It also has a variable heat control. I have used this for removing the glazing on 100 year-old windows with very good success.
I used the Jiffy Steamer that you use on windows for paint removal.
I used an aluminum foil backer on the window so the original glass would not be damaged.
It made the compound soft within seconds and I was able to lift it right off.
Just a question from someone who has never personally worked on windows, and is getting ready to start reglazing quite a few in my 1911 home. Does the glazing putty harden over time until it finally becomes so hard that it cracks and seperate by itself, or would this be a sign of water intrusion/poorly repaired putty over time?
I ask because, like Haldis, all of my windows seem to be coming off pretty easily with just my fingers--no damage to wood, no damage to glass.
>>Does the glazing putty harden over time until it finally becomes so hard that it cracks and seperate by itself, or would this be a sign of water intrusion/poorly repaired putty over time?
Traditional glazing putty has been carefully developed over the past four centuries to be easy to apply, work well for many years, and then fail gracefully. The way it fails is an important part of it. It fails so that it is easy to remove and replace with more putty.
People who are struggling to get the old putty out don't realize that it is often possible to leave it in place and do simple putty maintenance and spot repairs. I'm writing up these methods for a revision of my Save America's Windows book. Revisions always appear at the discussion forum at my website before the make it into the book, so keep track of developments there: