Sash Deglazing, and paint removal (with Video)

Remove old panes & putty, cut & clean glass, putty & paint.
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Sash Deglazing, and paint removal (with Video)

Postby johnleeke » Sat Mar 08, 2014 7:32 pm

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

Steam Deglazing

There are four deglazing setups that use steam to soften the putty:

1. Portable Steamer, lowest cost of about $50, good for onsite or shop bench work:
(scroll down to see details below)

2. Po' Boy Steam Box, build your own in an hour with $90 for materials and steam generator, shorter steam times than 3. or 4. To build your own see these instructions, materials and tool lists:

3. Steam Box, or the "Portable Steam Cabinet" as developed by Dave Bowers who provides written instructions to build your own in about 6 hours, $150-250 for plans, materials and steam generator:
(scroll down to see video below)

4. The Steam Stripper, developed and manufactured by Marc Bagala, stainless steel chamber with attached steam generator, costs about $4,000 to $7,500 including shipping and installation with plumbing and wiring, suitable for high production situations over the long-term:

Portable Steam Deglazing

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. This video has production times broken down by step, 52 minutes total for deglazing, all exterior paint removal, 30% selective interior paint removal, ready for painting and glazing. It probably would have taken less time for complete interior paint removal, say 45 minutes total.

At minute 14:20 in the video you can see where I've removed paint from the margin of the face of the sash, so the sash less likely to generate lead-containing dust and the associated health risk.

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 slight 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.

Steam Box with Infra-red Lamp

Video: The sash is placed in a box that is filled with steam. The steam softens the old putty and paint so it is easy to remove by scraping. An infra-red heat lamp is used to soften interior paint so it can be scraped off down to bare wood.

--19 minutes direct labor to remove the glass and all of the old paint and putty
-- Pull-type scraper quickly removes the old front putty and points; use a tool-steel scraper, not a carbide scraper, which would scratch the glass
-- Narrow crack tool quickly removes putty at edge of glass pane; make a crack tool by grinding a linoleum knife
-- Glass panes loosened with finger tips and taken out with no breakage, so it can be reused
-- Paint removed from exterior face of stiles and rails with pull-type scraper, all paint removed down to bare wood
-- Infra-red heat lamp used to soften and remove remaining interior paint
-- Profile scraper removes paint from profile with one or two strokes; profile scraper is custom made
-- Result: wood sash cleaned off down to bare wood, ready for next step in Complete Refurbish procedure

For questions and comments on this method: click on "post reply" below

Get the Save America's Windows Book:

Further important discussions:

Scraping the moulding profiles of sashes with profiled scrapers:

Is dipping sash a sin? If so, your purgatory is The Brown Ooze: ... highlight=

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.

Tools and Equipment

Steamer & Steam Heads:

To make several steam heads with different shapes and capabilities I've used ShopVac vacuum heads, which cost $5-10. The plastic used by ShopVac holds up to the steam. It can be easily cut and formed with a coping saw and utility knife. It can be heat-welded and re-formed with heat. The ShopVac "system" includes "wands" which I cut off and attach to the steam hose, so the different steam heads fit right onto the hose.
Image Image
Here I've cut some parts off the vacuum nozzle with a coping saw, to make a steam head for heating up the front line of putty. It has a built-in swivel feature that makes this steam head convenient for deglazing on the bench, the easel or onsite with the sash still in the frame.

I have published a Report from the Field on Steam Paint Removal, which covers methods, techniques, equipment, sources, making custom steam heads and profiles of three steam paint removal projects.
21 pages, 23 illustrations, 2 step-by-step methods on making custom steam heads. See it here: ... .htm#Steam

See this discussion on steam methods:
and equipment: ... =2663#2663



Stortz tools are well-known for their quality. At $12 each these scrapers do not seem over-priced. Their only downside is the wide acute bevel. As I use and re-sharpen this scraper I made a narrower and more obtuse bevel that controls the cut and make an edge that lasts longer. They are Made in America, and I'm now recommend the Stortz scraper over Marshalltown's scrapers, which are made in China.
More info and source: ... raper.aspx


Gloves for steam deglazing and steam paint removal:

I like "Atlas Therma Fit"


Manufacture's info:
The glove is like terry cloth inside so it acts like insulation to help protect from heat. The rubber coating helps keep the insulation dry. Get several pairs and change them as they get wet (from sweat or steam condensation) because if wet they don't insulate from the heat as well.
Cost: about $40 for a dozen pairs

Videos of steam box deglazing:

Marc Bagala, Maine, steam chamber: ... -stripper/

Dave Bowers, New Hampshire, steam box: ... ash-332641

Dave Kuns, Washington State, steam chamber: ... 0216#10216

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Re: Sash Deglazing, and paint removal (with Video)

Postby johnleeke » Fri Jul 25, 2014 6:00 pm

Lynn Stasick demonstrates his custom made steam chest in West Virginia:

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Tips to Reduce Glass Breakage

Postby johnleeke » Tue Mar 03, 2015 4:41 pm

Tips to Reduce Glass Breakage when Deglazing

--First consider if the pane must actually be removed from the sash--a good strategy if the glass is particularly thin and fragile. Perhaps spot putty maintenance will be adequate. Perhaps only the front putty needs to be removed because the bedding putty is in good condition and the glass is still tightly sealed.

--If using a heat method to soften the old putty: Before you start, gently warm up the whole pane slowly and evenly. The National Parks Service has a method of reducing heat cracking during deglazing by gently warming a sash before using any heat method of deglazing: Work in a warm shop, 80degrees plus, slowly warm the sash in a box that brings the temp up to 110-120degrees The heat in the box is dry air, not steam. Then deglaze using a heat method, usually hot air gun or infrared. This reduces the localized temperature difference, which is what cracks the glass. This also tends to dry out the sash so the wood is narrowed and the pane is looser, but don't heat the sash too long or you'll get drying checks in the wood.

--Chemical Stripper: I did use chemical stripper once. The pane had important names and dates going back nearly 200 years scratched into it with a diamond ring. Breaking the pane was absolutely out of the question. Method: test 3 different chemical strippers and pick the one that works best; brush it on the putty keeping it off the wood and glass; let it work for half an hour; scrape off 1/32" to 1/16" of the softened putty with a pull-type scraper; repeat. The bed putty was still good so we left the pane in the sash. It took four hours, during which time I also deglazed two other sash using more ordinary methods. I billed three extra hours to cover the slow-down on this one sash, one hour during deglazing, and two hours for special handling (protected the sash with ply on both sides and foam around the edges during all handling and moving). This was considered "conservation" level work, a step beyond ordinary preservation or repairs and maintenance.

--Turn the temp on your hot air gun down as much as possible and still get some softening effect on the putty. 250F. to 350F. should be hot enough.

--Also try an infrared heat lamp. Clean both sides of the pane before starting. The infrared rays will pass through clean glass and not heat it up. Dirt or grunge on the glass can catch the infrared rays and heat up the glass.

--Remove the little line of putty from between the edge of the pane and the neck of the glazing rabbet. A crack tool makes this go slick and quick. This helps loosen the pane from the glazing rabbet.

--Always lift the long edge of the pane up first. This puts less stress on the pane because it is across the shorter dimension of the pane.

--Keep a written record of how many panes you don't break and do break. At the end of every day or week add then up and compare with your past record. Also, occasionally write down how you feel when one comes out particularly well, and how you feel every time one breaks. This will put your subconscious mind on notice to help you improve.

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Posts: 149
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Wagner Steamer Adapter

Postby johnleeke » Thu Aug 31, 2017 3:26 pm

Adapting the steam hose of the Wagner 705 Steamer so it fits the standard 1 1/4" steam heads. The steam warms up and softens the old hard putty so it is easier to scrape away.

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