Wood filler around window frame not setting

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Adam78

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I have a wooden window frame, I think it is an old softwood type casement window where the glass is putty pointed from the outside into the frame. Due to condensation over the years the bottom part of the frame from the inside is slightly rotting away because the condensation trickles down the glass and then sits on the surface of bottom frame - the part where the timber touches the glass.

I scraped out any rotting wood approx 3-4mm along the length of the bottom frame. I tried to fill it with ronseal multipurpose filler but the filler never seems to set and that's after 24 hours. I think the frame is still damp and the filler is probably soaking up the water.

Whats the best way for me to fill this gap so that it can be repainted and provide a water tight seal to prevent any condensation trickling down between the glass and frame. Should i use a 2 pack filler instead and use a silicone seal to completely seal it?

Any tips and advice would be appreciated.
 
Two part filler , goes off in less 10mins regardless of moisture , but won’t stick to wet timber .
 
Scrape-out punky timber, treat exposed timber with wood hardener (e.g. Bonda Wood Hardener) to ensure that it is in effect waterproof and stable, 2-pack wood filler (or even car body filler) left 20 to 30 minutes to set thoroughly 9The stuff I use is a bit slower) - build-up in thin layers if more than 4 to 6mm of fill is required as thick layers set far more slowly, sand off when fully set.

The wood hardener is a polyurethane compound as is activated by the presence of water which it effectively absorbs.

2-pack filler requires a temperature of at least 5°C in order to set, so you can't use it on cold days (same goes for wood glues and wood hardener). 1-pack filler is for decorating and is generally quite useless for woodwork (regardless of what it says on the tin/tub) as it will shrink over time. Added to that many of them are water-based so they are destroyed by frost and won't set at all if too cold, either. BTW the timber must also be above 5°C as well to avoid it chilling the two pack filler - so if the previous night was cold you'll need to leave it to warm-up in the sun for a few hours. 10 minutes attention with a heat gun won't really work, but will quite possibly crack the glass.

If I had a pound for every time I've had to explain this to contract managers or site managers - I'd have a ruddy good night out in the pub!
 
JobAndKnock said:
Scrape-out punky timber, treat exposed timber with wood hardener (e.g. Bonda Wood Hardener) to ensure that it is in effect waterproof and stable, 2-pack wood filler (or even car body filler) left 20 to 30 minutes to set thoroughly 9The stuff I use is a bit slower) - build-up in thin layers if more than 4 to 6mm of fill is required as thick layers set far more slowly, sand off when fully set.

The wood hardener is a polyurethane compound as is activated by the presence of water which it effectively absorbs.

2-pack filler requires a temperature of at least 5°C in order to set, so you can't use it on cold days (same goes for wood glues and wood hardener). 1-pack filler is for decorating and is generally quite useless for woodwork (regardless of what it says on the tin/tub) as it will shrink over time. Added to that many of them are water-based so they are destroyed by frost and won't set at all if too cold, either. BTW the timber must also be above 5°C as well to avoid it chilling the two pack filler - so if the previous night was cold you'll need to leave it to warm-up in the sun for a few hours. 10 minutes attention with a heat gun won't really work, but will quite possibly crack the glass.

If I had a pound for every time I've had to explain this to contract managers or site managers - I'd have a ruddy good night out in the pub!
Click to expand...

Thanks for the tips. Which 2-pack wood filler do you use? I've tried the ronseal 2 pack filler but with the natural colour it's difficult to tell when the hardner is thoroughly mixed in becuase it's white. It would help if the hardener was a different colour so that it's easier to see when your mixing it with the filler.
 
If you want to see if it's fully mixed and the end result will be for painting then I'd recommend using a car body filler such as Isopon P38. This has (maybe had, it's a while since I used it) a grey filler body but a red hardener so it's really easy to see if you've mixed thoroughly. To slow the setting time simply add less hardener - time and experience will teach you how much/little to use

If you are doing a lot I'd recommend getting a low-cost 2in/50mm flexible stopping knife like the Prep stopping knife sold at Toolstation (£4.95) rather than the piece of plastic carp the manufacturers routinely supply with the can. Before use this will need to be broken-in by rounding the edges off a wee bit (in the absence of an oilstone pull over and flex back and forth over a stone step or paving slab to reduce the sharpness - in some ways like the way a barber strops a cut throat razor except that you are actually trying to dub the edge over) and the corners will need rounding off to a radius rather than a sharp chisel edge. Doing that reduces the tendency of the stopping knife to dig-in or leave track marks when spreading filler. Don't ever use it as a scraper - it is too thin for that and may break! After use always, but always clean the blade thoroughly and if needs be remove the last of the filler using a bit of sandpaper held tightly over an offcut of skirting or the like (i.e. a flat surface)
 
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