How do I remove glass from window without breaking it?

[bethrob99]

I have an old sash window with coloured and patterned lights. It has been seriously neglected for decades and has a broken coloured light. I managed to grab another sash window from a neighbour who was dumping it (similar condition) so have the correct size/colour piece of glass in another frame. I need to remove it from that frame without damaging it to swap with my broken one. I know I'll have to carefully remove all the old broken putty but what should I do about the rusty nails securing the glass. I can't just use the neighbour's sash as that also has a cracked pane.

Also, should I completely remove all the glass panes from my window, clean everything up and reglaze, repaint etc or should I just remove as much of the old putty as I can. I'm thinking the glass has to come out before new putty goes in as it is sort of 'bedded' on the inside or could a good glazier get round this.

PS I do not want to fling it and get a plastic window instead. I know it would save me a lot of time and effort but I liked the original window.

 

[ladylola]

As it's only the glass you want from the sash and not the sash itsself then the best approach would be to cut through the tenons and tap the whole thing apart. Do this on a flat surface on an old piece of carpet or something soft and you'll find the panes pretty much just slide away from the glazing bars.
As to wheather you need to remove the glass completely from your sash depends on the condition really, you may well get away with just removing any shot external putty , repriming and reputty.

 

[bethrob99]

Thanks for your answer. The putty is in a bad way. Half the external putty has fallen out of its own accord and quite a bit of the internal stuff is loose, powdery or missing altogether. Some of the panes were so loose, I was afraid to wash the window in case the pressure popped them out completely.

 

[Harbourwoodwork]

Its a bit of a game ,getting the glass out without breaking it ,glass gets brittle when old ,chip the putty out with an old chisel or hacking knife take it out if it will come easily then hack the putty out prime and re glaze but if its well in there, leave the old glass in clean and prime the rebate this is important because this helps seal the new putty into the frame and stops the linseed oil leaching out into the frame wait until the putty skins over then re paint