Sash windows

[Walsh53]

Hi guys my 1st time posting just wondering what is the best filler to use in previously painted pitch pine sash window. There's a lof of sanding and filler needed on the flat surfaces as they were let go too far. Hopefully not a two pack as it is hard to sand.
I would appreciate your help please

 

[Feltwell]

Welcome to the forum! What part of the window are you trying to fill?

Internally, I find the two-pack Ronseal filler works well - easy to mix and not hard at all to sand.

https://www.restexpress.co.uk/acatalog/Ronseal_High_Performance_Wood_Filler.html

Externally - you can use the Ronseal stuff, and I have for very minor bits of filling, but I think a 2part epoxy will last a lot longer. Bad news is, it's both expensive and very hard to sand. Preparation is key. I use the Chemfix Timbabuild system.

If an external cill is really bad it can be better to take the window frame out and replace the whole cill.

 

[malcolm]

I'm a huge fan of linseed oil paint - takes a long time to dry, goes dull, might go mouldy if you have a poor supplier, might only last a week if you have a poor experience like Feltwell, but it never cracks. Modern materials most always crack as a failure mode so you get water in when they fail and it can't get out again so it causes the damage you presumably want to fill.

Worth studying. Should you suddenly be converted it is dead quick to rub linseed putty into the cracks with your fingers and then paint straight over. You can't sand linseed putty unless you wait a year for it to dry, so the repairs will be under finished paint level. Linseed putty would be poor under any other type of paint unless you allow drying time.

It takes 5 posts on here for your replies to appear without some days delay. 4 posts in the test forum speeds things along.

 

[Feltwell]

I've gone off linseed paint for reasons of durability on horizontal surfaces and huge drying times, am now trying microporous water based paints - Bedec MSP - and so far I'm very pleased, with how easy it is to use, how quickly it dries and how well it seems to stick. Ask me in 10 years if I've made the right choice to switch :wink: .

On a cill that I repaired with linseed putty and then painted with linseed paint, the linseed paint (Holkhams - Allback) has now started to lift - OK, it's taken 7 years to happen, but it has.

One thing's for certain - your typical modern Dulux or similar gloss or satinwood, they really don't last.

 

[Me!]

... but I think a 2part epoxy will last a lot longer. Bad news is, it's both expensive and very hard to sand.

U-Pol Easy One is the filler I have used for years. It is much easier to sand than any other I've tried, and a good price too I think.
https://www.amazon.co.uk/Easy-Light-Weight-Filler-Litre/dp/B01HN5RVNI/ref=sr_1_5?ie=UTF8&qid=1540190923&sr=8-5&keywords=u-pol+easy+sand+filler+3.5

 

[Feltwell]

... but I think a 2part epoxy will last a lot longer. Bad news is, it's both expensive and very hard to sand.

U-Pol Easy One is the filler I have used for years. It is much easier to sand than any other I've tried, and a good price too I think.
https://www.amazon.co.uk/Easy-Light-Weight-Filler-Litre/dp/B01HN5RVNI/ref=sr_1_5?ie=UTF8&qid=1540190923&sr=8-5&keywords=u-pol+easy+sand+filler+3.5

Whilst I'm sure it's good stuff, that's more of an equivalent to the Ronseal one I posted above. The Timbabuild epoxy is a different beast entirely - it's not a lightweight filler, it's more the consistency of Araldite, it's a wood repair system - sort of glue-come-filler that can be used for splicing in new pieces of timber as well as filling and repairing existing. You prime the affected area first with a 2-part epoxy liquid, let that go off a bit, then mix up the filler (which comes in a 2-part tube and needs a special gun to dispense). Sets hard but with a bit of flexibility still in it, I'm much more optimistic that it will last a long time in a vulnerable external position than a lightweight 2-part filler, it's certainly a lot stronger and stickier - more of a structural than a cosmetic repair, if that makes sense. I only use where I think it will have a benefit over a "normal" filler though, as it's expensive, takes longer than a normal 2-part filler to apply and cure, and is harder to sand.

 

[Me!]

... Sets hard but with a bit of flexibility still in it, ...

Ah, now that is interesting. So do you think it seems flexible enough to move with the general thermal expansion etc. of a window frame and stay bonded to the wood?

 

[wobs]

For internal, I've stopped using the Ronseal filler, and moved onto Tetrion. Its similar, in that its a two part filler, but spreads smooth better.
https://www.trade1st.co.uk/tetrion-powerfil-2k-filler-1litre

For outside, I use the epoxy filler like Feltwell. Not cheap, but you can work it smooth, and is much more durable, and sandable.

Still use the linseed paint, but the use LinseedPaint Company paint, as it dries a bit quicker, and a bit more forgiving than normal linseed paint. And it possible lasts longer.

For large areas of rot, you need to splice in new wood, and assuming its outside, use epoxy resin to join the old with the new.

 

[Feltwell]

... Sets hard but with a bit of flexibility still in it, ...

Ah, now that is interesting. So do you think it seems flexible enough to move with the general thermal expansion etc. of a window frame and stay bonded to the wood?

It seems to. I used it on the bay window that I restored, a typical section is on the picture below - the new, darker hardwood is spliced onto the old timber and the (stainless) screw heads covered using the epoxy. Despite the timber being very well seasoned, after about 6 months I noticed that the new timber had shrank slightly leaving the epoxy filler ever-so-slightly proud at the screw heads and at the joint to the old timber - but it hadn't lost it's bond at all. Sanded it down and repainted and all is well.

It will only take movement up to a point of course - on the picture above, the corner joint on the timber came apart - I had to drill dowels across it to reinforce it, then re-fill with the epoxy. It's been fine since then, and the rest of the joints (below) have been fine.

It's pricey stuff, especially to start with as you have to buy the applicator gun, primer and epoxy tube - but I have to say it seems to do a proper job. Definitely key to get the epoxy as smooth and as well shaped as you can whilst it's wet, minimise sanding. If you search for "Timbabuild" on YouTube the manufacturer has put application videos up.

 

[CliffordPope]

[/quote]

Ah, now that is interesting. So do you think it seems flexible enough to move with the general thermal expansion etc. of a window frame and stay bonded to the wood?
[/quote]

There are plenty of marine glues and fillers that obviously have to be flexible, so it might be.