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Glaze and Paint Sash, traditional

Posted: July 6th, 2013, 3:26 pm
by johnleeke
Glaze and Paint Sash, Alt. D, traditional

Status: [ ] submitted work method, [x] proposed treatment standard, [ ] final treatment standard
Update: 4/15/13
Author: John Leeke
References: “Save America’s Windows”, pages 74-82.
Contributors:

Title of Treatment: Glaze and Paint Sash, traditional
Class of Treatment: [ ] Identify, [ ] Maintain, [ ] Stabilize, [x] Repair, [ ] Upgrade, [ ] Exception
Type of Treatment: [x] Traditional, [ ] Contemporary, [ ] Conservation

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

Description:
The sash and glazing rabbet is pre-treated, the pane is set in a bed of putty and held in place with points. The front putty is placed, packed and tooled to form a neat bevel and miters. The sash is primed and painted with two topcoats. This procedure is suitable for double-hung sash that are new and unprimed bare wood, or old sash with all panes, paint and putty removed down to bare wood, all woodwork repairs done, and all wood surfaces smooth and clean.

Typical Procedure:
1. Pre-treatment. Apply a pre-treatment of linseed oil and turpentine to the glazing rabbets.
This treatment may be extended to the rest of the sash if needed due to weathered wood surfaces. Apply a pre-treatment to the bare wood. Apply the pre-treatment to both faces of the sash, all muntin bars and muntins. Apply some extra at every joint, so it soaks into the joint treating the end-grain within the joint. The bottom edge of the lower sashes' bottom rail may need treatment if it shows signs of deterioration caused by water. If the bottom edge is in good condition it should not be treated since it has done well for so many years without treatment. Do not apply pre-treatment to the side edges of the sashes and the top edge of the upper sash. Allow to dry.
2. Sand Wood Surfaces. If needed, lightly sand off any nibs or whiskers. All surfaces and arrises should feel smooth. Dust off with a HEPA vacuum and tack cloth.
3. Prime the Sash. Do not prime the side edges of the sash that run in the tracks. Do not prime the top edge of the top sash or the bottom edge of the lower sash. Prime all other surfaces of the entire sash, except the glazing rabbets if they were already pre-treated. Apply the primer by hand brushing, working the primer well into the surface of the wood. Wipe off edges of sash with a rag to remove any beads or drips of primer. Allow to dry thoroughly.
4. Sand Primed Surfaces. If needed, lightly sand off any nibs or whiskers. All surfaces and arrises should feel smooth. Dust off with a HEPA vacuum, or brush and tack cloth. If primer was sanded off to bare wood in any spots or areas, re-prime those spots.
5. Bed the Panes. Lay all panes into the sash to assure that they all fit. Remove the panes. Keep track of where each pane will go. Kneed the putty in hand to warm it up. Apply putty to glazing rabbets as bedding around all the rabbets in the sash. Place each pane of glass on the bedding putty and be sure the bottom edge of glass is actually resting on the neck of the lower glazing rabbet. Jiggle the pane slightly with your fingers along the edges so that it beds down into the putty, leaving at least 1/16" of back putty between the glass and the shoulder of the glazing rabbet, with some putty squeezing out all along the edges of the glass. Panes wider than 24” may require spacer blocks between the edges of the glass and the neck of the glazing rabbet.
6. Set Glazing Points. If the panes are smaller that 6” or 8” set at least one point on the short edge and two points on the long edge. On larger panes set points away from the corner of the glass at least one forth the length of the edge of the glass, and then set points every 8” to 10” in between.
7. Tool the Face Putty. Place and pack each line of putty around the entire sash. Tool the face putty. Tool the surface of the putty to form bevels on an angle so the edge of the putty at the pane is directly across from the arris of the shoulder of the glazing rabbet. Form neat miters at the corners where the bevels meet.
8. Polish and Clean the Pane. Safety: wear goggles and a respirator when polishing with whiting to keep it out of your eyes, nose, mouth and lungs. Polish the outside of the pane with whiting in a dry soft paintbrush immediately after tooling. It is good to get whiting on the surface of the putty. Sweep out any remaining buildup of whiting from the lower corners. This cleans oil from the putty that got on the pane during the glazing process off of the glass and "dusts up" the surface of the putty to promote drying and skinning.
9. Tool the Back Putty. Flip the sash over and trim out excess putty that squeezed out from the bedding with a putty knife. Do not push too hard against the pane, or the pane may move and disturb the face putty on the other side of the pane. Tool down the back putty to form a watertight seal at the joint between the glass and the wood. Make the putty flush with the wood.
10. Polish and Clean the Panes. Polish the inside of glass panes with whiting, the same as Step 8. Set sash aside in correct vertical position, leaning slightly back, to avoid settling of glass and distortion of the putty bevel. Allow enough time for putty to cure or skin over.
11. Prime the putty, if needed. Some putty and paint combinations need to be primed, others do not. Check with the putty and paint manufacturer to determine if the combination in use should be primed. If needed, apply primer to face putty bevels and interior seals. Lap primer 1/32" onto the glass, painting "to the line" and allow to dry.



12. Topcoat the sash and putty. Brush on by hand, two topcoats of paint to entire sash except side edges and top and bottom edges if they are not being painted. Begin by lapping paint 1/16" onto to glass while painting the line of putty, then paint the rest of the stile, rail or muntin, then move on to the next line of putty. Wipe off the edges of the sash with a rag to remove any beads or drops of paint. Set sash aside in correct vertical position to avoid settling of glass and distortion or wrinkling of putty and paint. Allow enough time for paint to dry and cure thoroughly.

Materials:
· Rags
· Sandpaper, 100 grit
· Tack cloth
· Pre-treatment, mix of linseed oil and turpentine
· Primer, oil-based linseed oil or alkyd resin
· Turpentine
· Linseed oil
· Putty or glazing compound
· Glazer’s points
· Whiting
· Paint, oil-based topcoat house paint or exterior enamel

Quality of Results
Quality of results are judged by touching the glazing and painted surfaces and by visually standing three feet from the window on the interior and ten feet from the window on the exterior.

Best Work:
Before priming or painting check to see that the bedding putty is tightly sealed to the pane and interior arris of the moulded profile. Putty must be firmly packed into the glazing rabbet, in and around the edge of the pane, with the face putty showing an even bevel, neat miters at the corners and a tight seal all along the glass and wood. After painting, all painted surfaces feel smooth to the touch. DO NOT press the surface of the putty with a finger or dent it with a fingernail when touching the surfaces. Visually, all the painted surfaces have an even sheen, with no gaps at the edges of the putty or at the sash joints. A slight variation is acceptable in the line of paint as it meets the glass, since painting to the line is a hand technique. Glass is clear of oily smudges and fingerprints, dust on the surface of the glass is acceptable.

Adequate Work:
Before priming or painting check to see that the bedding putty is tightly sealed to the pane and interior arris of the moulded profile. Putty must be firmly packed into the glazing rabbet, in and around the edge of the pane. The face of the putty can show a slight to moderate unevenness and the miters can be slightly irregular, there must be a tight seal all along the glass and wood. After painting, all surfaces feel smooth to the touch. DO NOT press the surface of the putty with a finger or dent it with a fingernail when touching the surfaces. Visually, all the painted surfaces have an even sheen, with no gaps at the edges of the putty or at the sash joints. A moderate variation in the line of paint as it meets the glass is allowed. If the line of paint varies by more than 1/8”, straightening it by cutting it with a razor blade and straight edge and scraping off the extra is allowed. Glass may have localized spots of dried putty oil or specks of paint, which must be cleaned off.

Inadequate Work:
Surfaces feel rough, arrises feel sharp. There are gaps at the edges of the putty or at the sash joints. Fingerprints show in putty and on painted surfaces, and there are holidays (areas without a coating of paint) on painted surfaces. Dirty glass.

Re: Glaze and Paint Sash, traditional

Posted: July 6th, 2013, 3:48 pm
by johnleeke
This is the method I have been using for 40 years, with good results. I know that at least two of the window preservation shops use a traditional method similar to this. It is the method that is in all the old trades manuals.

The main difference between this method and the other contemporary methods currently set as standards, is that this method beds the panes in putty and leaves the points in, while the contemporary methods bed the panes in caulk or sealant, often without points.

Re: Glaze and Paint Sash, traditional

Posted: July 19th, 2013, 7:40 am
by oculus
This is the procedure that I use out here in Oregon. I have had no problems with it over the years.
I did do some remediation consulting on a project and had to look at a lot of technical bulletins for products and some glazing compounds require thicker back bedding than the 1/16" listed with this procedure.
But overall this is an excellent procedure for traditional linseed oil application.

Re: Glaze and Paint Sash, traditional

Posted: July 19th, 2013, 1:59 pm
by johnleeke
Amy, thanks for your insight.

What were the glazing compounds or types of compounds that required thicker back bedding than 1/16".

Re: Glaze and Paint Sash, traditional

Posted: July 21st, 2013, 6:32 am
by oculus
During the remediation consulting work I did these past couple of years I dived into Daps technical data sheets. Within those documents it states that Dap 33s bedding thickness has to be at an 1/8th inch minimum. And it also limits Dap 33s use to panes of glazing 48" or less in any one direction.