Replacing a Georgian window pane

[ljn]

Yesterday a decorator cracked a window pane. The glass is of the wobbly type - crown glass?
Nine panes out of 45 have already been replaced with modern picture frame glass, but if possible, I'd like to replace with glass that makes the trees beyond go wobbly.

Can you get old glass from reclaimers? Or does anyone make it?

 

[ljn]

Should have looked first. I found this company: http://www.londoncrownglass.co.uk/
about £100 per square meter, so a little pane will be well under £20
Only the hassle of collecting it.

 

[ljn]

"It is a commonly held misconception that all historic windows were glazed with crown glass. Both cylinder (or broad) glass and crown glass methods of handmade flat glass production survived alongside each other until the 20th century..."

http://www.buildingconservation.com/articles/glazing/glazing.htm

 

[Moo]

I seem to remember Penners recommending greenhouse glass as an economical substitute.....

 

[Nigel]

Tatra P1 Restoration glass has been mentioned before. I have tried and failed to extract glass from old sashes; neither sawing or putty extraction worked - the glass cracked. You need a heat lamp.

I agree though, don't use modern plain glass - our house is almost entirely crown glass and it throws wonderful images on the internal walls on a sunny day.

 

[MdB]

Agricultural glass has been mentioned before as well - it is supposed to be cheap because the surface is wavy which is what you want. Know nothing about it myself.

 

[biffvernon]

Despite what it say on the box, the London Crown Glass Company does not make or sell crown glass. Nobody makes it any more.

P1 from Tatra Glass is a hand made mouth blown cylinder glass from Poland and is probably the best you'll find for such a job.

 

[Feltwell]

My house is much later than yours (1899) so whilst the original glass is still "wobbly", I suspect less so than perhaps an older property - can anyone validate that?

I looked at horticultural glass at my local (very friendly) merchants, they said that whilst it used to contain ripples in years gone by the stuff they get now is almost distortion free - they showed me a sheet and I coudn't see any imperfections at all. Shame becuase I was hoping that would be a nice cheap option!

You can get old glass out of sashes without either cutting the wood or using a heat lamp, I have managed it, but it is tricky. A glazier's hacking knife is essential I found - mine came off Ebay, about £5 from memory.

 

[philmac1944]

Just a thought. Using modern glass can upset the balance of sash windows.
You can usually find sash weights ( mice ) at salvage yards.
Good luck.

 

[biffvernon]

In 1899 most glass was machine drawn. It has the occasional horizontal ripple, rather than the complex patterns of cylinder glass. Yes, horticultural glass is often very near perfect.

 

[Andrew Bodenham]

Reclaimed glass is the way to go, but you'll probably have to reclaim it yourself. Best way is to watch as you drive around for the dreaded double glazing van, nip in quick and ask them if you can have the old sashes they're ripping out. Maybe offer the guys some beer money so that they don't break the glass. You can pick up some spare sash weights, pulleys etc. this way too.
Alternatively visit the workshop of a d.g. company and bribe them to not dump the next load of sashes in the skip but stack them up for you to take away.

Getting the old glass out can be tricky, but sometimes it's surprisingly easy. My prefered method is simply to cut through the sash frame at the corners; you can usually tap the whole side of the frame off with gentle hammering. The putty is often pretty knackered and puts up little resistance - it's the corroded and expanded glazing sprigs that tend to start the cracks.

I've found that reclaimed glass cuts really easily - much easier than modern. Nice sharp cutting wheel, dipped in oil, clean the glass surface first, one good clean stroke with the glass on a flat surface, couple of taps on the back and bingo!

 

[ljn]

Thanks all.
I needed a quick fix. The windows are being refurbished and I took the opportunity of them being out of their boxes to have them decorated.
I have ordered a pane, plus a couple extra, of the P1 Tatra Glass (thanks Biffvernon) They sell through various retailers, so I am able to pick it up in a relatively close Camdem glass shop.

I'll keep an eye open for skips. I always do...

 

[Jon Maine]

For anyone who needs glass Eastern European horticultural glass is very good, its made on old machinery so comes out with blemishes and distortions at a small fraction of the price of P1. Not to be confused with modern horticultural which is float glass and to flat entirely inappropriate.

 

[Feltwell]

Have you just been able to get that from a local glass merchants Jon?

 

[Jon Maine]

No, for all of our leaded lights, some 80 in number Wessex Conservation from Wells made them and supplied the glass. Very, very reasonably indeed here is there web link http://www.wessexconservation.co.uk/ they may well be able to supply you

Personally I prefer their glass to P1 which appeared to be a bit overly done when it came to both the markings, deficiencies and certainly the price. Quality glass would have been used where it could be afforded which you could see through albeit with a bit of distortion which is where the Eastern European seemed to fill that gap.

Most glass merchants seem to sell 3mm float glass for horticultural which is entirely inappropriate, although I guess it may be worth checking your local ones.