I need to make an old-fashioned wood storm window and plan on glazing the glass with DAP 33 glazing and have 2 questions.
First – I’ve read some old posts mentioning putting a film of BLO on the wood and glass prior to bedding in the glazing compound. The DAP spec sheet says to prime the wood with oil based primer but says nothing about BLO. What would you think would be the best way to prep a poplar frame for glazing?
Second – how much glass should be bedded in the frame? I have a Whiteside window sash bit set that would be ideal for making the frame but the bit only gives me enough space to get 1/4″ or so of glass bedded in the glazing coumpound. This is OK for small panes of glass on a divided light sash but I’m concerned that on a single pane the size of a storm window, I need to increase the width of the rabbet to allow more glass contact. Should I?
Thanks for your suggestions!
Rob
Replies
The general consensus is that you want to put SOMETHING under the 33, to keep the wood from drawing out the oils. Shelac is sometimes used, or a primer.
My impression of BLO (just had to look it up) is that it's more of a "liquid sandpaper" product, intended to improve adhesion between paint layers, and would not be such a good idea on raw wood.
1/4" bedding would be the bare minimum for a full-sized piece of glass. Probably 3/8" is closer to the norm, though I guess I'd never really thought about it before. Use glazing points.
Boiled linseed oil is a good thing to use under DAP33, to prevent wood from pulling the oil from the compound. I have seen frames that have a routed groove at the top of the opening to receive the glazing (glass) so that it holds the glass in place on the top, the rest is held in with points. I was a glazier for a few years, and I always hated putting in points because it's very easy to crack the glass.
I would bed the glass in a good grade of caulk then use DAP33 compound for glazing over the glass. Make sure the BLO is compatible with your caulk or dont use it on the bedding surface.
I never understood the small width of the bedding surface, but 1/4" is normal, sometimes it's less and it's hard to sink the points far enough in to hide them, then there is a risk that they won't hold the glass in place. Glass needs a little clearance, don't try to fit it tight, or there is a good chance it will crack later on.