[dwmatson]

I am working on a table-building project involving a walnut slab that has a number of defects (knotholes, etc.) that I would like to fill with clear epoxy prior to sanding flush and applying a rub-on polyurethane finish. Many of the resins available have a yellow or amber cast when poured to any thickness, which would be undesirable. The slab is approximately 3″ thick and some of the defects go completely through the slab, so would have to be sealed on the backside prior to filling. There is also a fair amount of bark in some of the holes, which I would like to retain to add interest to the finished table. Any suggestions as to the optimal product to use as a fill material, and/or techniques that would maximize the opportunities for success on this effort?

 

[Steve Neul]

Can you post a picture of the wood? It's hard to visualize needing to fill a void 3" deep with a clear filler. What I have done on knot holes that go all the way through is to mix some brown color in bondo and use to fill it with. They do though make a clear epoxy filler made for deeper applications.

 

[Oneal-Woodworking]

I am working on a table-building project involving a walnut slab that has a number of defects (knotholes, etc.) that I would like to fill with clear epoxy prior to sanding flush and applying a rub-on polyurethane finish. Many of the resins available have a yellow or amber cast when poured to any thickness, which would be undesirable. The slab is approximately 3″ thick and some of the defects go completely through the slab, so would have to be sealed on the backside prior to filling. There is also a fair amount of bark in some of the holes, which I would like to retain to add interest to the finished table. Any suggestions as to the optimal product to use as a fill material, and/or techniques that would maximize the opportunities for success on this effort?

You want the West Systems epoxy for that and it is not cheap. You want the kit with the pumps because if you don't get the ratios just right - You WILL have a hard mess quickly or be waiting for weeks and weeks...

You can use tape on the bottom to keep the epoxy from running out and then sand it all back flat again after things dry. I usually use the clear box tape and I use a LOT of it when doing this sort of work.

 

[epicfail48]

Dagnabbit, Oneal stole my answer! Anyway, yeah, what he said, expensive though it may be epoxy is still the most cost effective way of filling a gap that large

 

[Brian T.]

Another option is methacrylate resin (aka Plexiglas), commonly used acros the fiberglas industry.
Water clear. Looking at boat hulls, you can see how it can be tinted any color you like.

I'd fill the holes 1/2 - 2/3 full and let that set up. Next, a layer of interest such as turquoise, metal filings, etc with a little fresh meth for stability. Last fill to the brim with clear

 

[dwmatson]

thanks to all for your input. Am thinking the West Systems epoxy is likely the way to go given the input here and from what I've read elsewhere. It sounds like several small incremental pours are needed to avoid overheating from the reaction of the epoxy setting.

 

[was2ndlast]

Cut out the knot/defect and plug it with a piece of walnut. Both sides. Sand flush.

I think epoxy does not look nice on furniture.