Glaze Sash, contemporary (final)

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

Glaze Sash, contemporary (final)

Postby Bob Yapp » March 8th, 2012, 6:11 pm

Update: 3/10/12
Author: Duffy Hoffman

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

Condition to be treated: Sash needs to be glazed.

Bedding the glass pane into the glazing rabbet, apply and tooling traditional glazing putty.

Sash is oil primed. Sand sash with a medium grit sanding sponge. Wipe and clean sash with wet rag. Glass is cut, pre-fit into opening and cleaned, ready for setting.

Typical Procedure:

1. Apply a bead of sealant on the bed of the glazing rabbet. Use only enough sealant to cover the bed. Do not apply sealant to more than three lights at a time, because the sealant may set up too fast and not adhere well to the glass.

2. Lay the pane into opening, making sure there is a 1/16" space at all four edges. Press the pane lightly and evenly into the bed.

3. Remove most of the excess sealant from the edge of the pane with a putty knife. Clean up remaining sealant with a small paint brush wetted with water by brushing lightly around glass.

4. Install glazing points to temporarily hold the glass in place.

5. Turn the sash over to work on the interior side. Tool and lightly push the sealant into any small gaps in the joints where wood meets glass. Repeat the same cleanup as in step 3 above. Turn sash back over with the exterior side up and lay on flat surface.

6. Repeat steps above for each sash, placing wood sticking (wood strips) on top of the sash previously laid down, stacking the sashes up to a safe level. Allow the sealant to cure 24 hours.

7. Remove all glazing points from sash. The sealant in the bed will hold hold the glass making the points unnecessary. Remove any excess sealant from both sides of the sash with a knife. Use care to not damage the wood and paint with the knife.

9. Clean the face of the glass panes near the edges on the exterior side with a rag and paint thinner.

10. Prepare the glazing putty by filling a quart size container and mixing in a small amount of fine whiting. Keep adding the calcium carbonate until the putty does not stick to your hands.

11. Use a small ball of the prepared putty and warm it in your hand. Apply putty with a glazing knife. Form the bevel of the putty on an angle so the putty cannot be seen from the inside of the sash. Create crisply shaped mitered corners.

12. Smooth the putty with a small soft paint brush that is wetted with clean water.

13. Sprinkle whiting on the putty then brush it off with a dry paint brush. Use a small vacuum or air hose to remove the excess whiting. Hang or stack sashes for drying. Re-sprinkle the putty with whiting for two days. On the third day the putty should be skinned over enough for priming and painting.

•Sealant, elastomeric, 100% acrylic, paintable, waterborne
•Glass panes, old, reproduction, new recycled, or new glass
•Glazing points
•Traditional glazing putty
•Paint thinner
•Sanding sponge, medium grit
•Whiting, calcium carbonate

Quality of Results:

Best Work:
Glass is bedded evenly with sealant. Points were removed and putty installed smooth and even with crisp miters in the corners. Putty cannot be seen from interior side of sash.

Adequate Work:
Glass is bedded evenly with paintable caulk. Points were not removed and putty installed smoothly but a bit uneven with miters in the corners not perfect but able to shed water. Putty cannot be seen from interior side of sash.

Inadequate Work:
Glass is bedded unevenly. Putty was installed on dirty glass and is rough or uneven, allowing water entry or holding water. Putty can be seen from interior side of sash.

Posts: 3
Joined: June 22nd, 2011, 2:25 pm
Full Name: David J Garner
Location: Silverthorne, CO
Organization: Total Environments,
Permissions: Yes

Re: Glaze Sash, contemporary (draft)

Postby davidjgarner » November 5th, 2012, 11:43 am

For those whom to choose to use Silicone as back bedding vinegar is the solvent, yes?

On the Park County (CO) Courthouse project, we were instructed (by the liaison of the SHPO’s Office) that if putty was firmly adhered to the substrate, not to remove it, even though there is no back bedding. The liaison believes that approach is in keeping with the Secy of Interior Standards. We will not warranty that approach. Trust y'all agree.

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

Re: Glaze Sash, contemporary (draft)

Postby Bob Yapp » November 5th, 2012, 1:24 pm

Totally agree!

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