Epoxy Pore Filling Part 2: Prep & Application of Second Coat

[matthewclara1]

I'm applying zpoxy to a padauk ukulele. After lightly sanding the second coat, I see that everything looks and feels pretty good, except the pores themselves are still shiney, as though they are lower and not getting sanded. Do I need to sand down to the point the pores are no longer shiney? Should have I done that after the first coat, and not be worrying about it now on the second?

Thanks again for the great vids!

mc

[matthewclara1]

@matthewclara1

In response to my own query: more sanding is required. Considering your description of "light sanding" in your videos, I must have applied too much, or simply didn't remove enough of the first coat. Of course, I did it all by hand, i.e., with a block (and then without for those areas that weren't perfectly flat!).

[MDLuthier]

Tooth with Scotchbrite and do another coat to fully fill large pores...sanding back to the lowest filled pore will almost always open more pores.

[matthewclara1]

@MDLuthier I ended up doing a little more sanding (not to the wood) and then a third coat, and now it feels like glass. Well, satiny glass, 'cause I hit it with the scotchbrite again after it cured. All the pores are now flush with the surface (ok, maybe not all of them, but 98%, for sure, and the ones that aren't are tiny, and near the edges, and I'm afraid to mess with them too much more). Now that no wood's exposed and everything is flush, should I apply a fourth coat of epoxy?

[MDLuthier]

@matthewclara1 I think you are good to go...tooth with Scotchbrite and shoot sealer. Any pores that are still just a little low will fill during finish.

[matthewclara1]

I'm not clear from the videos--how long do you wait between zpoxy applications, and how long do you allow it to cure before applying lacquer/poly?

Thanks for the vids, btw--very informative.

[MDLuthier]

I usually end up doing a coat a day, and shooting my forst sealer coat over the epoxy filler as soon as I'm done sanding.

[matthewclara1]

I'm not clear from the videos--how long do you wait between zpoxy applications, and how long do you allow it to cure before applying lacquer/poly?

Thanks for the vids, btw--very informative.

[sarelle500gr]

this look great, I need to try this. Doen't epoxy is harmful for the wood? Or does it make the wood's surfece too hard? I mean harder than we want?

[MDLuthier]

Sarelle:

No problem - not harmful, and any additional stiffness is usually beneficial for sides and back. If used on the top for something like filling a mahoganyy or koa-topped instrument, I account for the slight increase in stiffness with a very slightly thinner top...something around .003".

[sarelle500gr]

Thank you!

[bighank99]

Todd, I'm still not clear as to how far back you sand back the epoxy filler. Do you leave epoxy on areas between the pores?

[MDLuthier]

Hank -

Two options: sand back to wood or send until the surface is level and dull. I only snad back enough to level and dull, then apply the next coat. If you do choose to sand back to wood, keep in mind that you may open additional pores - particularly on figured, open-pored stuff. Also - on mahogany, anigre, koa, and other large-pored woods, the epoxy will penetrate a bit further into the wood, so it gets more difficult to sand back to bare wood...in that case, stick with just leveling

[bighank99]

@MDLuthier

Thanks for the tip. As you mention in your 3rd video, you have to trust that the dull epoxy finish will take a finish and not detract from it.

The first time I tried it I didn't trust and sanded the whole thing back way too much.

thanks again, Henry L.

[MDLuthier]

Good luck, Henry - shoot me a pic when you finish it up - love to see it.

Todd

[MDLuthier]

Thanks...hope it is useful

[albertaboyz]

Way Cool!! Thank you for sharing your knowledge.

Cheers