Using epoxy with Douglas Fir

[Benchwayze]

Hi folks,

I want to use up some old Douglas Fir for the legs of a small workbench. The timber was first milled to about 9 x 9 many moons ago, and I quartered it about five years ago. Since then it has been in my shop, so it's aclimatised and is nice and dry. It always had shakes in it, up to eight or ten inches long. None of the shakes are much above 3/16ths wide, and I think they have 'shaken' as much as they are likely too. They haven't altered since my re-sawing, and I think they will fill nicely. Apart from appearance, I don't see them causing problems with joinery, as long as I fill them well. What to fill them with though. I thought about epoxy, but I have never used the stuff. I don't know what grade or type to buy and also I think I'll need a good amount.

Has anyone any experience with using epoxy as a filler please? I know it can be coloured, but is it okay to mix it with sawdust for bulk?

Or should I just use Polymite/Cascamite, mixed with dyed sawdust? :-k
Or maybe I should just go and buy some 102mm square construction grade softwood? :mrgreen:


Thanks in anticipation

John

 

[Phil Pascoe]

https://www.toolstation.com/shop/p55454?table=no

 

[Brentingby]

You can use sawdust as a filler for epoxy but sanding dust would be better. Sawdust in epoxy leaves a a very rough surface. Sanding dust will be much smoother. If mixed to the right consistency, it'll still flow. Heat the wood if you can before adding the epoxy. Pour in a bit of unthickened epoxy first so it can soak into the wood. Then add the thicknened epoxy to fill the gap.

Epoxy won't adhere to smooth plastic so for cracks or shakes that go through, you can cover gap with plastic such as clear packaging tape on plywood. Remove it when the epoxy has hardened and you should find a smooth shiny surface.

 

[Benchwayze]

That should do the trick Phil. Many thanks. I had considered Brummer stopping but I have had it dry and fall out. Plus its shelf-life is abysmal. That's if there is any left!

Brent;

Thanks for the info, there is one shake that goes almost clear through, but I might be able to cut that one off, as there's plenty of length. Decision time then!

Cheers

John

 

[Phil Pascoe]

John, if you've not used two part filler before and especially if you're working somewhere warm the stuff goes off in minutes so don't mix too much at a time. If you put in on too thickly you can cut it off easily with a chisel while it's still "green" but not when it's hardened properly. Don't put a used filling knife back into the tin, use something clean.

 

[rafezetter]

2 part paste style wood filler is good if the defect isn't deep or whatever, but for shakes I think liquid epoxy dribbled in with a backer of masking tape works better as it'll penetrate into the wood a little and fill all the voids fully.

I generally use fibreglassing epoxy as it's cheaper than west systems stuff, but I have also used basic grade moulding epoxy too (that's yellow) both of them can have a filler added to make it a bit thicker for larger cracks - I personally use "Imperial leather" talcum powder as it has a nice scent that actually masks the horrible epoxy smell, which can linger a while indoors (personal experience). The moulding epoxy can be found online pretty cheap - both types of epoxy. liquid or paste can be dyed with powder paints, graphite powder, slate sanding dust, metal powders like aluminium, pretty much any coloured powder. You can also use paint, but be sure to mix it well before adding hardener.

On that note you can slow down the catalytic process by adding less - the usual mantra is 1 pea size hardener to golf ball - however the amount of hardener can be adjusted up or down to take local temps into account (less for hot days / more for cold) or if you want more working time, don't be tempted to add more "just in case" it almost always ends up with a stuck spoon and wasted epoxy - I've gone as low as 1/3 the required hardener and it still fully went off, it just took 8 hours to do it, but it meant I could muck around with what I was doing for over an hour without worry the batch would go off.

Playing with epoxy and wood is fun and will lead you to all sorts of solutions to things once you have it as a regular part of your arsenal.

 

[Racers]

I used lots on some pippy oak the pound shop one works well, mixed with coffee for colour.

Pete

 

[clanger]

Pour in a bit of unthickened epoxy first so it can soak into the wood. Then add the thicknened epoxy to fill the gap.

Along a similar vein, my Father-in-Law (a retired boat builder) recommended to me to use West Systems with a Slow Hardener. His reason for slow was so that the epoxy had time to soak in and then go off.

Chris