Putty and reglazing

[Lobster]

I glazed a window a few years ago - timber casement window, single-glazed); however the putty along the bottom rail cracked after not too long and fell out.

I'm about to have another crack at it; hoefully this evening while everything's nice and dry - any top tips on how to avoid a recurrence?

For the original job I used a tub of conventional linseed-oil-based putty; cleaned out and sanded down the rebate; bedded the glass on a bead of putty and then applied putty on top, pressing it down well and finishing off with a 45-ish degree chamfer. I waited a few weeks until it had gone hard before painting with oil-based paint.

There were actually two window frames - in the other, the painted putty just pulled away a bit from the glass leaving a crack for ingress of water, but otherwise stayed in place. In both frames the problem is confined to the bottom rail of the window only.

Thanks for any advice... David

[Nick Odell]

Touch wood, I haven't needed to do a job like that for some years but as far as I can see, I used to do it exactly like you did and the results were fine. Was the putty fresh? I've been tempted to use old putty that's gone stiff by kneading it back to suppleness and adding more linseed oil but in the end I've gone out and bought fresh each time. Hence the putty-mountain in the cupboard under the stairs. I'd be interested in what the experienced contributors have to say about the problem - and about whether I should just chuck my old putty away.

Nick

[Paul D Smith]

You may have waited too long. I did this a few years ago and only waited a few days for the top of the putty to set before painting. Three years later when I sold the flat, the putty still looked fine and I suspect the underlying stuff was still a little soft.

Paul DS.

[Andrew Gabriel]

I painted new putty with oil based gloss (which you probably can't get anymore), and it caused the smooth putty surface to pucker up into fine crickles (some reaction between the solvents I presume), but apart of the strange surface texture, it worked fine. I presumed I had painted it too soon, although it felt like it had set, at least part way.

[stuart noble]

IMO linseed putty is useless unless you have room for a thick bead of the stuff. Even then it doesn't last long on south facing windows. Acrylic putty is vastly superior IME

[chris French]

The only other thing I might have added was to seal the rebate first with primer or knotting solution. As these helps stop the linseed oil from leeching out into the wood of the frame from drying out.

Yup that's what I used in the old house, worked fine.. Did use putty here though, as old Victorian windows, and I like to keep to the old materials. also I was painting the window with linseed oil paint and didn't really know how that would play with acrylic stuff.

[Lobster]

I always thought linseed was de rigeur for timber windows? It's a stonking bead (ie the chamfered bit), incidentally. Faces East, FWIW.

David

[NT]

Linseed putty's excellent stuff, and bonds the glass and wood together to maximise whole window strength.

Years ago I used some very old putty, most of the tub had set, and having no oil or gloss paint to hand I just added a few drops of water to what I could scavenge from the tub. No problems at all with it. And no, I dont do that sort of thing these days.

NT