Tricks for Removing Old Glazing?

[Corsetière]

I am slowly chipping away at the glazing on one attic window and wondering if you guys have any tricks for getting it clean faster?

[heartwood]

the safest and easiest way is to put the sash in a steambox to soften the putty...if you plan to
do all the sash in your house then it may be worth the investment...materials for the box cost under $100...the
steamer itself costs about $250 but you can find them on ebay for less...there are plans for building the box are the 'reference department' heading here...

it is best practice to remove all the putty, the glass and the bedding putty then treat the dry wood with blopentine...if the putty is so hard that you end up breaking glass, you may want to just remove what you can then brush the remaining old putty with blop...then apply new glazing to the old...

how far do you want to take the project?
...jade

[Gothichome]

Corcetiere, if I have any issues getting the cement hard putty from my wavy glass I only remove the loose stuff and follow Jades plan. Don’t want to risk my wavy glass. If was a replacement glass I put the effort in to remove. If it brakes no lose.

[Willa]

I have followed Jade's advice and only removed what was crumbling or loose, then patched in new glazing putty. I tried to use a putty that I thought would have the greatest chemical similarity to the old putty so I used Sarco or Allback, both linseed based glazing compounds. I replaced loose or missing glaziers points in the repaired areas.

My patches have held fine and when done neatly then painted it is indistinguishable from an intact old window.

I have also been too enthusiastic trying to dig out putty that wasn't loose and broke several panes this way, which I always find hair-raising.

[Casey]

A few years ago I stumbled into a new technique for removing putty, and it seemed to work well on the 1860's sash we were removing/reglazing. The windows were on a street and extremely grimy, so I started washing them with hot water and detergent. I noticed that when I applied the heat gun to begin excising the putty, it was popping out instantly. I further refined the technique by scraping the paint off the glass right where the putty meets it. The science of this is that the water gets in, but the heat gun makes it steam right there inside the putty.
We had tried building a steam box, and that met with some success, except for the fact that the steam indiscriminately took the paint off the inside of the sash as well, which was not permissible the way the contract had been written, or desirable to my boss to pay us to then sand, prime, and paint-match the inner surfaces.
This works very efficiently if the sash are removed from the jambs and can be paid flat so the water/detergent can soak in. 5 minutes was all that I allowed it; the time factor dropped from an hour per sash to 10 minutes for the putty removal phase, so the boss was happy. And the glass breakage dropped to almost zero.

[Corsetière]

Al good points. @Jade, I generally tend to do things completely because I don't like to revisit a project. Get it done right the first time! lol!

Yeah I may have to patch in new putty. I did buy some Sarco and some more WoodEpox to fix the frame damage. I think someone's dog is actually responsible for the damage on the lower parts of the frame, not rot like I previously thought. It looks like nail claw marks after I got the paint off.

I don't have very many original windows here unfortunately so a steam box probably isn't worth making. I think I will go outside with a respirator and try casey's method with a heat gun first and see where that gets me. Thanks for the input guys!

[1918ColonialRevival]

Heat will soften putty, just be sure to keep the heat gun moving, don't leave it in one place, and frequently check the softness. Otherwise you'll risk cracking the glass.

[Mick_VT]

Heat will soften putty, just be sure to keep the heat gun moving, don't leave it in one place, and frequently check the softness. Otherwise you'll risk cracking the glass.

an old baking sheet as a shield can help

[GibsonGM]

To shield, I use a 9" taping knife for larger glass pieces, or a 4" one on smaller. You can jam a dowel in the hole in the handle to keep it at about a 45-degree angle to your work. No more broken glass! You may need to move it a little to keep the glass covered at the ends, but it's a decent way to do it.