We've a little problem with our wooden windows and will be indebted to anyone who can advise. Our Victorian flat has several sash windows with bare wooden frames. The trouble is that indoors they attract condensation, which rolls down the glass and has been causing black mould at the glass/wood join and all over the rebate. I'm in the process of sanding the interior of the frames down to bare wood, with the intention of using wood hardener and varnish of some kind all over the wooden frames. However it looks to me like the thin layer of putty between the glass and the wood is old and cracked and dried out, and is perhaps allowing water that rolls down the window to get into the timber. Before varnishing, I want to remove this old putty from inside and replace it but I don't know how to do it. The old putty comes off fairly easily, so I am thinking I might be able to just use tweezers and a putty knife to rake out the loosest bits, then replace the thin line of putty from the inside, using linseed oil putty. Is this a reasonable approach and if so how do I go about it? I do not want to do a full line of putty onto the glass as this will spoil the look of the frames, just maybe force some new putty into the gap between the wood and the glass to prevent ingress of water. Thanks in advance for any ideas.