Historic HomeWorks Forum

[johnleeke]

Steam Deglazing, Portable

Deglazing is removing the old putty and the glass from the sash.


Video: sash deglazing with the portable steamer at the bench.

This method can be used in the shop on the easel or bench, and onsite with the sash still in the frame.

[johnleeke]

I've used the CRL Putty Softener



in past years. It does work, but the risk of glass breakage is greater than some other methods. Be sure to protect your glass with a pad of aluminum foil, about 5 or 10 layers thick, folded to exactly cover the glass, and develop a technique and timing to avoid charing the outer edge of the glazing dado (aka glazing rabbet).

When we switched away from the CRL Putty Softener, to a Makita hot air gun with controllable temp and air volume (along with our custom-made air baffle:



our glass breakage rate dropped from 23% to 15%.

Other methods, such as steam,



have dropped our glass breakage rate to 2% or 3%.

I still occasionally use the CRL Putty Softener, and the hot air gun, for certain circumstances, like when we have a lot of glass that is broken already and cannot use steam.

I would hesitate to use the CRL Putty Softener on a sash that is still installed in the building because this is a high-temperature dry-heat method that can start wood, and paint or putty debris on fire. In the shop, where the situation is more controllable, it might be safer, but in recent years I have not even used them in the shop--why would I risk burning down my shop, when there are effective alternatives? Measures can be taken to significantly reduce the fire risk, but they take time and dollars.

[johnleeke]

Also, see this discussion on scraping the moulding profiles of sashes:

http://historichomeworks.com/forum/viewtopic.php?t=987

[johnleeke]

Deglazing is removing the old putty and the glass pane from the sash. This might be necessary to replace the pane or to take apart the sash for further repairs. Often deglazing must be carefully done to preserve the glass for reuse.

There is no secret or product that makes removing the glass panes easy. Some good methods have been developed that eliminate the struggle, but it is still work. The two keys to effective deglazing are to warm up the old putty and use a pull-type scraper to remove it. To do this work safely wear safety glasses and gloves to prevent cuts, and follow lead-safe work practices.

Back in the 1970s a common method was heating the putty with the old standard Masters Red hot-air gun, protecting the glass from breakage caused by the blast of hot air with aluminum foil pads folded ten sheets thick. The putty could be pried the putty loose with an ordinary putty knife. This worked, but it was slow and blew around a lot of lead-containing dust, and broke a lot of glass. Typical glass breakage rate was 30-40%.

In the 1980s hot-air guns were available with controllable air temperature, controllable air volume and a flat nozzle. With settings for limited air and the least temperature necessary glass breakage rate dropped to 20-30%. A custom-made air baffle that kept the hot air off of the glass and eliminated the need for the aluminum foil pads. With the use of a pull-type scraper production rates doubled and the breakage rate dropped to 10-20%.

It is possible to use an infra-red paint stripping lamp to warm up the putty. This works, but the lamps are 4” wide and it is difficult to control all the heat they generate. Shining the heat on an area of exposed bare wood can result in charred wood. You have to work on a heat-resistant surface--an ordinary wooden bench top may char and catch fire. This is a ‘dry’ method, so it generates lead-containing dust that must be controlled. Using the lamp itself is slick and quick, but following high level Lead-Safe Operations adds to the time and cost.

A method using steam to soften the putty has been developed in recent years. This is slick and quick and can be used in the shop on the easel or bench, and on-site with the sash still in the frame. It is a damp operation so that helps control the lead dust, and lower level of Lead-Safe Operations applies, which is easier to implement. One disadvantage is that the steam can soften the wood if it is scraped the wrong way or scraped too much, resulting in “scruffed” surfaces or “threading out.” It is possible to develop techniques to limit this damage. A portable steamer with a hose can be used. Special steam heads can be made that guide the steam right along the line of hard putty. It takes just one or two minutes of steam to soften the putty so it crumbles out easily. With steam typical glass breakage rates are only 2-3%. Whole sash can be steamed in a box made of foam board insulation, or in a stainless steel chamber.

Once the putty is soft, use a pull-type scraper to remove it. If you use a putty knife or chisel you will be pushing toward the glass, which is what breaks glass, especially when you slip, or the putty gives way all at once. To keep from breaking the glass do not make ANY movement, force or pressure toward the glass when scraping out the old putty--not perpendicularly toward the glass, not even at an angle toward the glass. All movement near and on the glass must be parallel to the glass or away from the glass to prevent breakage. Use a pull-type scraper. If you slip, or the putty gives way, all the force is away from the glass and it will not break.

Remove the glazing points. This is easy to do with a pull-type scraper. The sharp edge of the scraper hooks into the soft metal of the point and pulls it out right along with the putty. Double-check to make sure all of the glazing points are removed. Also, check to see if the old putty beside and under the edge of the glass is loose. If not another round of steam or heat-lamp may be needed with a little edge scraping with a crack-tool.

Handle glass carefully. When removing and handling glass always lift or pry it along the longer edge. This puts the stress across the shorter distance of glass making it less likely to break. To work the glass loose from the sash, grip the stile or rail of the sash with your thumb on top or toward you, with your fingers underneath or behind. Put the tips of your fingers against the inside edge of the wood sash where it meets the glass, and your fingernails against the glass. Gently curl your fingers, levering between the end of your fingers on the wood, and your fingernails on the glass. This presses your fingernails against the glass in a very controlled way. The very sensitive nerves in the ends of your fingers can detect the slightly movement. If you feel no movement in the glass, shift your grip to other areas along the edge and try again, working back and forth along the edge, until there is some movement. Watch this ‘working edge’ and the other edges of the glass to see where the glass is not moving, and check that out to see what is holding the glass. A glazing point or spot of well-adhered putty may be holding it there.

Also, working on the sash on an easel in a near vertical position rather than laying flat on a bench helps some workers reduce their glass breakage rate. It is a well known technique in the glass trades to always store and handle glass vertically to prevent breakage.

[Uchmar]

I do not have skill and experience like many of you, but several times I successfully used oscillating tool (Fein) to remove putty without damaging the glass (needed to be re-used elsewhere). Painting was not needed because old paint was in very good condition so only new putty was repainted. Obviously any use of heat would lead to repainting.

Tool is used to cut vertically along the edge of the rabbet just a fraction of the inch into the putty. Then you cut under 45 degree angle from the glass side towards the rabbet edge. You may cut under smaller angle, but carefully not to hit the glass. While working at one frame I reversed the process by doing 45 degree angle cut towards rabbet edge first, and this worked nicely with lot of putty coming off the rabbet without need for vertical cut. It is not necessary, but the blade can cut glazing points.

Work is fast and it is not messy because oscillating blade moves very little and does not create much dust. Also it does not chip and flip putty leaving putty parts and dust on the glass. Still, tool provides some air flow which may blow the dust, but I think it is quite possible to spray the water to prevent this.

[sschoberg]

I can tell your a technique type of person. You use tools with an appropriate style unique to the tools ability and yours too. That's a good thing. Thats a good idea to share.

[Mike-in-Maine]

I have a Rockwell SoniCrafter that I got last Christmas... I dont have a clue what it does, but I just did a google search on Oscilating tools and what do ya know? Its rated second only to the latest Fein tool. Guess I been sitting on a gem all this time. Its got a zillion accessories and a hard case for storage....

I still have no clue what it does or what I should use it on.... zero, zilch, nada, nothing.... (Ive never even plugged the thing in...)... I DID read through all the documentation it came with, which educated me on how to attach its doo-dads, but didnt tell me a thing about what it does...

[johnleeke]

The Rockwell SoniCrafter appears to be an exact knockoff of the Fein Multimaster.
http://rockwelltools.com/RK5102K.htm

It may have been a 'one run' knockoff though, even Rockwell's own website has dead 'buy now' links, and they have deleted their own videos showing how to use the tools. Although some of Fein's patents have run out I wonder if Rockwell got into legal trouble with their knockoff.

Anyway, yours probably works great and you should try it out. I've been using my Fein in window and other work since 1992. It's nice for controlled precise cuts in wood where you don't want to disturb the surrounding materials, such as removing wood at a decayed sash joint when the sash has to stay in the frame and you can't remove the glass. And, like Uchmar says, removing old putty with the offset bell-shaped metal cutting blade.

This video shows my Fein in use on a cornice soffit board repair:

[Mike-in-Maine]

I Just saw this great video showing how fast a steam box is. When I compare this to using a hand held steamer I want to cry. I *NEED* to make me one of these. The difference is 2 hrs of tricky careful and somewhat difficult work vs 45 mins of hands-off steaming and 6 minutes of quick easy work.

Watch!

[johnleeke]

Yep, that's Dave Bowers. He learned about steam boxes at my windows training workshop back about 2005, when we visited Marc Bagala's shop here in Portland to see his stainless steel steam chamber. Then Ginger in that same workshop went back to Vermont and saw two carpenters who had built a steam box out of foam board and powered it with an old coffee pot. Ginger posted a message about it here at the Forum and several of us started do it.

It really works.