Putty advice for sash windows

[Bingy man]

Neither was my father taught or told to remove the pins before final putty up. He always used pins, as did his apprentice (and the apprentices apprentice). My dad knew about glazing sprigs but never used them. In fact in the training chain the only person who used sprigs was the last one and that is because the (Council) COW insisted on inspecting before final Putty Up and the use sprigs was contractual. And the COW did not want the sprigs removing.

Glazing only cracks where the pin or sprig is because the metal is NOT flat to the glass.

Tbh I think it was a security issue as the local crooks would happily remove the putty gain entry , rob you blind and be kind enough to refit the glass before they left ,I was taught to slide the small pin hammer against the glass and gently tap the pin home as you said the pin is parallel to the glass not angled but I do see jacobs point but I never had any issues.

 

[niall Y]

Just because, one doesn't find glazing sprigs on some old windows does not mean that this is the norm. Because, equally, one does find them used.

Where they are difficult to use, and possibly best avoided, is on very thin glazing bars, where one is in danger of splitting the thin fillet of wood left between the panes, or even worse hitting an adjacent pane of glass and cracking it. Where there is enough meat on the stiles and rails this is not a problem. And if one is so minded, then they can even be tapped below the surface, off the edge of the glass, as one proceeds with the puttying.

I find sprigs a lot easier to use than panel pins as you can slide them flush on the glass Using a heavy firmer chisel instead of a hammer also helps as the bevel can be slid on the surface of the glass which helps stop them veering at an angle when they are going in.

 

[Glitch]

Can I recommend toupret brand glazing putty. It's basically modified linseed oil putty. Easy to use, white, paint in a few days, doesn't stink to bad and doesn't crack and doesnt smear. £9 a pot from the dulux centre. I reckon those water based heritage sealants are fine for double glazing but not that easy to use and not traditional for resto work.(not cheap either.)

I've just used the Toupret putty to replace some old cracked stuff.
Much easier to use than traditional Linseed putty.
Takes a few days to skin over.
Will have to see how durable it is but the reviews are encouraging.

 

[RupertV]

Left in they can fail by rust getting at them and causing cracks in the putty.
Also being a tight fit any shock to the glass can start a crack next to the pin.
Also they are pipper to extract if trying to take out a piece of glass, especially if rusted in.
If nailed in too tight they can start a crack at any time.
I did a lot of repair/restoration, mostly sashes, as well as new stuff and found these things out for myself - firstly by noticing that original old work never ever had pins or sprigs left in.
PS but of course you can leave them in and safe a few minutes on the job, and you might get away with it!

I haven't glazed a window in years but always used copper glazing (doesn't rust and were made for the job)sprigs which are like a miniature cut nail, tapped in with the edge of a bolster against the glass to below the putty line - never had a window crack (some done more than 40 years ago still good) and easy to remove with pincers. Job done.

 

[Jacob]

Just have to be patient with putty and wait for it to skin over. As a bonus you can leave it quite a long time before it must be painted.
In the end it's the cheapest, easiest to apply, longest lasting, easiest to maintain/repair.
Good idea to prime new work with stopping in rebates, on remedial work to apply linseed oil.
You can still buy 3mm horticultural glass which is often rippled and more like old glass.

Typo - "Knotting", not "stopping"

 

[Chubber]

I hesitate to post this in such a pedantic fashion in such erudite company but feel I must ....

Glazing sprigs should not be removed when the pane is set on a thin bedding of soft putty.

Consult the link I posted earlier - examine the pointed end of the illustrated sprigs. It is not some accident of manufacture that they are that peculiar shape. Just as a farrier's hoof nail has a bias cut point to guide it, so the tapered shape and pip steer the sprig gently against the glass.

It is inserted with the flattest straight edge to the glass, and generally set (for convenience) using the side of a 1" firmer chisel.

If you have one, a case-makers sprig set (hammer) shown below does a better/similar job.

Those of you that aren't already bored to a state of catalepsy will notice that the handle is offset to allow the long face to be slid flush/flat against the glass.

Feel free to call me a pedantic old scrote, although I prefer 'curmudgeon'......

Excuse me if I have repeated any previous post contents.

 

[Jacob]

I hesitate to post this in such a pedantic fashion in such erudite company but feel I must ....

Glazing sprigs should not be removed when the pane is set on a thin bedding of soft putty.

Consult the link I posted earlier - examine the pointed end of the illustrated sprigs. It is not some accident of manufacture that they are that peculiar shape. Just as a farrier's hoof nail has a bias cut point to guide it, so the tapered shape and pip steer the sprig gently against the glass.

It is inserted with the flattest straight edge to the glass, and generally set (for convenience) using the side of a 1" firmer chisel.

If you have one, a case-makers sprig set (hammer) shown below does a better/similar job.

Those of you that aren't already bored to a state of catalepsy will notice that the handle is offset to allow the long face to be slid flush/flat against the glass.

Feel free to call me a pedantic old scrote, although I prefer 'curmudgeon'......
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View attachment 185191

No need to apologise for being a pedantic old scrote I'm one myself! So I'm told.
Yes to the sprig flat side for better holding - panel pins have a head which means a very local point of contact and they take more force to tap in. That sprig hammer is a novelty! The point about sprigs is that they are easy to tap in with a pin hammer or heavy chisel, and they are easy to pull out.
You can leave them in if you wish but I never found them in original old work - I did loads of period windows including reclaiming the glass.
I also never used them in new work unless done in situ, where some support becomes necessary with bigger panes temporarily, but not permanently once the putty has gone off.
If left in they can become a problem and if sashes not maintained can rust and loosen putty.
Rusty panel pins are worse than sprigs to remove and I always associated them with badly fitted replacement glass, not original work.
But I hardly ever took glass out of any modern windows later than Edwardian, where big panes are common, but still without pins left in.
PS sprigs impossible to use with thin glazing bars such as you find in Victorian stuff, but completely unnecessary anyway with small lightweight panes.
PPS "Sprig hammers" seem to be a picture framers thing according to google. I'd never heard of them I'll have a look in Salaman.

 

[Fonix]

I’m pretty sure you can paint toupret putty after 7 days - at least that’s what I’ve been doing! Available from Screwfix.

 

[Jacob]

No need to apologise for being a pedantic old scrote I'm one myself! So I'm told.
Yes to the sprig flat side for better holding - panel pins have a head which means a very local point of contact and they take more force to tap in. That sprig hammer is a novelty! The point about sprigs is that they are easy to tap in with a pin hammer or heavy chisel, and they are easy to pull out.
You can leave them in if you wish but I never found them in original old work - I did loads of period windows including reclaiming the glass.
I also never used them in new work unless done in situ, where some support becomes necessary with bigger panes temporarily, but not permanently once the putty has gone off.
If left in they can become a problem and if sashes not maintained can rust and loosen putty.
Rusty panel pins are worse than sprigs to remove and I always associated them with badly fitted replacement glass, not original work.
But I hardly ever took glass out of any modern windows later than Edwardian, where big panes are common, but still without pins left in.
PS sprigs impossible to use with thin glazing bars such as you find in Victorian stuff, but completely unnecessary anyway with small lightweight panes.
PPS "Sprig hammers" seem to be a picture framers thing according to google. I'd never heard of them I'll have a look in Salaman.

Yes, Salaman says picture framers.

 

[Chubber]

Yes, Salaman says picture framers.

I'll take that, nice though, innit?

 

[duke]

I hesitate to post this in such a pedantic fashion in such erudite company but feel I must ....

Glazing sprigs should not be removed when the pane is set on a thin bedding of soft putty.

Consult the link I posted earlier - examine the pointed end of the illustrated sprigs. It is not some accident of manufacture that they are that peculiar shape. Just as a farrier's hoof nail has a bias cut point to guide it, so the tapered shape and pip steer the sprig gently against the glass.

It is inserted with the flattest straight edge to the glass, and generally set (for convenience) using the side of a 1" firmer chisel.

If you have one, a case-makers sprig set (hammer) shown below does a better/similar job.

Those of you that aren't already bored to a state of catalepsy will notice that the handle is offset to allow the long face to be slid flush/flat against the glass.

Feel free to call me a pedantic old scrote, although I prefer 'curmudgeon'......

Excuse me if I have repeated any previous post contents.
View attachment 185190





View attachment 185191

Now I have to look up three words which I have never read or heard before.