Thread: What to fill holes with?

For a clear filler, maybe straight epoxy resin?
I'd actually add some fine Jarrah sawdust to the epoxy, about 50/50 by volume, to make it look like dried sap.

Personally I prefer to tint it suitably to "blend" the knot into the grain pattern. (I'll often use coffee grinds... or even instant coffee at times! ) Because this is an opaque finish I don't have to worry overly much about air-bubbles, etc... and can 'get away' with using 24hr Araldite or similar. (Which is not really a "cheap" method when you try to buy Araldite in sufficient bulk. But it's usually more convenient to buy... )

If you want it "crystal clear" to make the knots into features, then you need to look at a more expensive 'casting resin' type. By which I mean that it is transparent, untinted, prone to little or no shrinkage and minimal bubbles. (Either in suspension or trapped by surface tension.) Perhaps a West system epoxy resin? I'm sure others here could point to a cheaper, just as effective source of the right stuff if this is how you'd like to go.

There's also Digger's Polyester Resin from Bunnings. I use this for casting and it's nice stuff. Also cheap(ish.) It does have a minor tendancy to shrinkage (it is a casting resin after all) which might make it unsuitable for this application... even though their site advocates it as "Filling in knot-holes in timber table tops."

Might be worth trying on a knotty offcut first?

Cheers guys, I will look at that. I did want to keep it clear so you can see the knots but just have it smoothed over so would probably look at the casting resin type deal.