Glaze Sash, Alt. C, contemporary (final)

bobyapp
Posts: 22
Joined: April 25th, 2011, 11:17 am

Glaze Sash, Alt. C, contemporary (final)

Postby bobyapp » January 8th, 2012, 6:57 pm

Number:
Status: [] submitted work method, [x] proposed treatment standard, [ ] final treatment standard
Update: 2/1/12
Author: Bob Yapp
References:
Contributors:

Title of Treatment: Glaze Sash, Alt. C, contemporary
Class of Treatment: [ ] Maintain, [ ] Stabilize, [x ] Repair, [ ] Upgrade, [ ] Exception
Type of Treatment: [ ] Traditional, [x] Modern

Condition to be Treated: Bare sash needs to be glazed.

Description:
Preparing the glazing bed for the installation of original or salvaged glass. Setting the glass into the glazing bed and installing new glazing putty.

Typical Procedure:

1. Clean the bottom and side of the glazing bed to bare wood using a carbide scraper.

2. Clean the glazing bed of all dust with a tack cloth.

3. Prime glazing bed with alkyd oil primer or apply a mixture of 50% boiled linseed oil and 50% denatured alcohol to the glazing bed. If using alkyd oil primer, add 1/8 cup of boiled linseed oil to each gallon for better penetration. Allow to cure until dry.

4. Dry fit the glass to assure proper fit. The glass should have a minimum of 1/16" play on all sides of the glass when fit. Apply painters tape to the glass and, using a marker, write the direction the glass fits into the opening for future reference and proper fit.

5. Lay a bead of caulk on the bottom of the glazing bed that just covers the entire bottom. If there is a groove in the meeting/check rail of the lower sash, fill it with caulk.

6. Carefully set the glass into the caulked glazing bed. Gently press the glass into the caulk so it squeezes out on the interior side.

7. Install glazing points to hold the glass in place. Fewer glazing points are better because the glass is actually held in place by the caulk once the caulk cures.

8. Allow the caulking under the bedded glass to cure over night or until it can easily be removed with razor blades.

9. Remove excess caulk from interior side of glass with a razor blade, and any small amount that squeezed upward into the glazing bed on the exterior of the glass.

10. Push putty into the glazing bed with your fingers or a putty knife. Creating a lot of pressure when pushing the putty helps it bond to the glazing bed and glass. Use a large amount of putty for easier removal once the putty has been tooled-in.

11. Tool the putty with a very stiff bent glazing knife. Apply a lot of pressure to insure better adhesion. The putty may tear out if there is not enough adhesion. The edge of the putty must be behind the sight lines of the interior molding profile by 1/16". This allows the finish paint to come onto the glass 1/16" without being able to see it from the interior side of the sash. Remove the excess putty and use it for the next run of glazing.

Each time you smooth a bead of putty, dip the tip of the glazing knife into boiled linseed oil. This skim of boiled linseed oil over the putty helps lubricate the pull, smooth the surface of the putty during tooling and also acts to help cure the putty enough to skin over for painting within 24 hours. This also alleviates the need to prime the putty as the boiled linseed oil becomes the primer.

12. Dress the corners into neat, even miters.

13. Allow putty enough time to skin over to paint, perhaps a few to several days. To speed up the skin over, blow air over the putty with a box fan and it can be painted within hours.

14. After the putty has skinned over, use razor blades to remove small pieces of putty left on the glass and then spread fine saw dust onto the glass and rub the oil off the glass. Be sure to stay 1/8" away from the putty to avoid damaging it. Vacuum off the saw dust. Regular glass cleaning can follow.

Materials:
• Oil-based alkyd-resin primer
• Boiled linseed oil
• Denatured alcohol
• Painters tape
• Felt marker
• Acrylic latex caulk with silicon, color to blend with the interior finish of the sash
• Glazing points
• Boiled Linseed oil glazing putty
• Small container for boiled linseed oil while tooling putty
• Fine saw dust
• Razor blades and safety holder

Quality of Results:

Best Work: The putty should be installed evenly with mitered corners. All putty is installed evenly and 1/16" behind the interior sight line. No putty should be seen from the interior side of the sash. No tear outs in the putty and very crisp mitered corners.

Adequate Work: The putty is installed well but not very smooth. Miters are marginal but acceptable. All putty is installed 1/16" behind the interior sight line.

Inadequate Work: Putty has tear outs, is not even or smooth. Mitered corners are sloppy and seen from the interior side. Putty is out over the sight lines.

johnleeke
Posts: 375
Joined: April 13th, 2011, 7:34 pm
Full Name: John Leeke
Location: Portland
Organization: Historic HomeWorks
Permissions: Yes
Location: Portland, Maine
Contact:

Re: Re-Glazing A Window Sash

Postby johnleeke » January 8th, 2012, 10:34 pm

OK Bob! The content looks good to me. I will make a few minor edits for wording, etc.

To me it looks good to go to public review.

Thanks.
John
Standards Co-Founder
Standards Editor

http://www.HistoricHomeWorks.com

restocarp
Posts: 3
Joined: January 11th, 2012, 11:41 am
Full Name: Matthew Hankins
Location: Baltimore, MD
Permissions: Yes

Re: Re-Glaze Sash (draft)

Postby restocarp » January 26th, 2012, 1:02 pm

bobyapp wrote:
5. Lay a bead of caulk on the bottom of the glazing bed that just covers the entire bottom. If there is a groove in the meeting/check rail of the lower sash, fill it with caulk.

6. Carefully set the glass into the caulked glazing bed. Gently press the glass into the caulk so it squeezes out on the interior side.



It seems to me that bedding the glass in caulk will make it difficult to safely remove in the future. Should glass not be bedded in glazing putty?

Matt
Matthew Hankins
Worcester Eisenbrandt, Inc.
Baltimore, Maryland
http://www.weirestoration.com/
http://askwei.blogspot.com/

johnleeke
Posts: 375
Joined: April 13th, 2011, 7:34 pm
Full Name: John Leeke
Location: Portland
Organization: Historic HomeWorks
Permissions: Yes
Location: Portland, Maine
Contact:

Re: Re-Glaze Sash (draft)

Postby johnleeke » January 26th, 2012, 2:33 pm

Hi Matt, welcome to the Window Preservation Collaborative.

The standard above is marked as a Modern (contemporary) method, there are many window specialists who use this method with a modern sealant for bedding.

Many window specialists do bed the glass in glazing putty. I'll be submitting a standard on a traditional method of glazing that includes bedding in putty, since that is the way I do most of my glazing.

Do you bed in putty? What are your methods and results with that?
John
Standards Co-Founder
Standards Editor

http://www.HistoricHomeWorks.com

restocarp
Posts: 3
Joined: January 11th, 2012, 11:41 am
Full Name: Matthew Hankins
Location: Baltimore, MD
Permissions: Yes

Re: Re-Glaze Sash (draft)

Postby restocarp » January 27th, 2012, 9:01 am

johnleeke wrote:Do you bed in putty?


Yes, all of the sash we restore has the glass bedded in putty. With, of course, the stipulation that if a contract mandated otherwise we would have to follow that contract. Also, we will bed glass held in place with stops, in caulk. We have also restored some copper clad wood sash with copper clad glass stops. In that case the IGU was bedded in silicone. The interiors of those sash were painted wood. Keeping the silicone off of the painted surface was a trick. One IGU did have to be removed later and, due to the cured silicone, it impossible to remove in one piece.

I missed the modern vs. traditional classification. I guess my thought would be that if any sash was going to be "putty glazed" that it should be bedded with putty as well. When I encounter a window that needs to be restored I look at the glazing material to determine how to remove the glass. If the glass is puttied in I assume that it is bedded with putty. If it turns out that it is caulked in, a higher percentage of the glass is a loss. One of my primary thoughts, throughout a restoration is: "Think of the next guy/gal." Reversibility is key, regardless of whether you are restoring a building that is historic now or will be some day. That being said, as illustrated above, sometimes caulks are the best material for the job.

Matt
Matthew Hankins
Worcester Eisenbrandt, Inc.
Baltimore, Maryland
http://www.weirestoration.com/
http://askwei.blogspot.com/

Bob Yapp
Posts: 59
Joined: May 9th, 2011, 8:39 am

Re: Re-Glaze Sash (draft)

Postby Bob Yapp » August 19th, 2012, 4:53 pm

Using acrylic latex caulking for the bedding material and then traditional putty is becoming the standard in the business. The seal for the putty is critical and I've found that when the glass is pressed to glazing putty, it becomes so thin that it dries out quickly and the seal between glass and bedding putty is quickly lost. Glass removal with caulk has never been an issue. The bedding caulk stays pliant longer than putty and can be warmed for glass removal.


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