Steam Deglazing, whole sash (final)

ATBagala
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Joined: August 2nd, 2011, 9:24 pm
Full Name: Ann Bagala
Location: Falmouth, ME
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Steam Deglazing, whole sash (final)

Postby ATBagala » January 25th, 2012, 1:10 pm

WPSC Window Standard Work Method Form

Number:
Status: [ ] submitted work method, [] proposed treatment standard draft, [x] final treatment standard
Update:
Author: Marc Bagala
References:
Contributors:

Title of Treatment: Steam Deglazing of Whole Sash
Class of Treatment: [ ] Maintain, [ ] Stabilize, [ x] Repair, [ ] Upgrade, [ ] Exception
Type of Treatment: [ ] Traditional, [x ] Contemporary, [ ] Conservation

Condition to be Treated:
Deteriorated window glazing, excess paint, failed paint, lead paint.

Description:
This method uses a steam cabinet to strip glazing compound and paint from wood or metal window sash, in preparation to stabilize, re-glaze and repaint sash. It is appropriate for restoration projects where it is desirable to remove all layers of existing paint, and for situations where the objective is to remove lead-based paint from sash. Because it is a wet method, it reduces the lead dust hazard usually associated with deglazing window sash. We have used this method in our shop for approximately fifteen years. Follow-up observations of projects completed using this method show that paint and glazing adhere well to steam stripped windows without paint or glazing failure. The procedure should be altered when stripping sash with plate glass. In that case, glass should be removed first using other methods to minimize thermal breakage, and then the sash may be steamed to remove paint.


Typical Procedure:
1. Heat steam chamber to approximately 200 degrees.
2. When working with sash with large panes of glass, bring the sash to at least room temperature or warmer, to reduce thermal breakage of glass in the steam chamber.
3. Place sash in steam chamber with the exterior of the sash facing up.
4. Remove sash from steam chamber after approximately 30 minutes.
5. Working on the exterior of the sash, scrape soft glazing away from the glass.
6. Carefully remove glazing points, glass and bed glazing from the exterior of the sash.
7. Scrape soft paint from exterior of sash.
8. For best results for breaking the paint bond, let sash dry overnight before re-steaming and attempting removal of the interior paint.
9. Steam sash for 30 minutes at approximately 200 degrees to soften interior paint.
10. Carefully scrape paint off interior flat surfaces using a sharp carbide scraper.
11. Let sash dry overnight again. (This allows any remaining paint to become brittle.)
12. Dry scrape brittle paint from ogees. (Do third immersion in steam chamber and allow to dry again if this paint is still difficult to remove.)
13. Sand all surfaces smooth to prepare for repair, priming, glazing, painting.

Materials:
• potable tap water
• 60 grit sand paper
• 150 grit sanding sponge

Quality of Results

Best Work: All glass, glazing compound and paint are removed. Minimal glass breakage (less than 5%). Wood is smooth and there is no evidence of damage (scratches or gouges) from paint removal.
Adequate Work: Some paint remaining. Glass breakage between 5% and 20%. Minor scratching from paint removal.
Inadequate Work: Remaining paint and glazing compound adhered to sash. Glass breakage in excess of 20%. Obvious damage from scraping. Loss of profile on sash parts.


Image

Image

johnleeke
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Re: Work Method Submission - Steam Stripping

Postby johnleeke » January 26th, 2012, 3:04 pm

Marc & Ann, excellent!

Materials:
I'd like to add water as a material. Should that be ordinary potable tap water? Also, since sanding is a step, what type and grit of sanding materials do you use?

The photos are really good. This method of steam deglazing will be new to many uses of the standards, could you provide a photo that shows a closeup of the finished result, bare wood, perhaps at joint of the sash?
John
Standards Co-Founder
Standards Editor

http://www.HistoricHomeWorks.com

ATBagala
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Full Name: Ann Bagala
Location: Falmouth, ME
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Re: Work Method Submission - Steam Stripping

Postby ATBagala » January 26th, 2012, 3:33 pm

John,

Yes, tap water is fine.
Sanding materials: 60 grit sand paper and 150 grit sanding sponge.

I'll see what we have for photos for this as well.

Ann

jlindtner
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Re: Steam Deglazing, whole sash (draft)

Postby jlindtner » January 30th, 2012, 1:20 am

Perhaps including a line something like: Results may vary depending on the age of the window and size of glass. Dwell time of sash should be tested and started at 20 minutes in the steam cabinet while glass is still in the sash. If the putty and paint are still too hard and there is no glass breakage additional dwell time should be added. (I've had too many 1-lite sashes from the 1920s crack since the glass is so tight in the glazing rabbet.) I've also found that the putty is usually soft enough after about 20 minutes without having to spend an extra 10 minutes in the steam cabinet.

johnleeke
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Re: Steam Deglazing, whole sash (draft)

Postby johnleeke » January 30th, 2012, 12:47 pm

John, all good points, all true in my experience as well.

As editor, the guideline I'm applying is that we are saying "what" is done so someone who does not know about the method can recognize if the method is being used.

We don't have to get into "how" to do it, covering all the possibilities. Making the timing description more flexible than "approximately 30 minutes" is possible. What do you think Ann?

I think it IS important to cover the most common pitfalls of the method, and I'll base that on further discussion. Has anyone had other problems with this method?
John
Standards Co-Founder
Standards Editor

http://www.HistoricHomeWorks.com

ATBagala
Posts: 6
Joined: August 2nd, 2011, 9:24 pm
Full Name: Ann Bagala
Location: Falmouth, ME
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Re: Steam Deglazing, whole sash (draft)

Postby ATBagala » February 8th, 2012, 2:24 pm

John & John,

These are excellent points. Marc and I discussed this and we recommend adding the words "or very large panes of glass" after the words "plate glass" in the description section. Also, for steps 4 and 9 we recommend changing the wording as follows:

4. Remove sash from steam chamber when paint and glazing compound are soft (approximately 20-30 minutes.)

9. Steam sash until paint on interior surface is soft (approximately 20-30 minutes).


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