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Hi guys,
I applied a coat of Zpoxy to a Mahogany solid body and neck.
The end grain is very dark. Should I try to sand most or all of it back to wood?
How consistent does my sanding need to be? Will dark and light areas show through subsequent coats?
My Zpoxy is new, the resin is just barely amber.
Thanks

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If you decide to sand back to wood, you may want to use a wood sealer before recoating to minimize that happening.

Dan, I use zpoxy for two purposes. First, as a pore filler I put it on full strength and sand back level with the surface trying to leave just the pores. In that case you should be able to get most of the darkness out of the end grain.

The second function is enhancing the grain - for that I want to use the characteristic that zpoxy wets the wood (like wiping with alcohol or naphtha). In this case I highly dilute the resin with DNA and apply with a foam brush - most of it soaks into the wood (at different rates depending on cross or end grain or figure). There is very little sanding after the enhancement coat, I just seal and finish over that.

Here is a mahogany body with the full strenght pore filling resin application before level sanding



Here is the other side of that guitar. Maple, as you know, does not need pore filling. After doing the fade stain I put one coat of zpoxy diluted with DNA on the top, it really pops the grain.

Another solution is to use a water clear epoxy finish coat (especially on lighter woods like maple) like West Systems.

I know a lot of folks like to sand back to wood. I do not. Well, I do, sort of, but then I apply a highly thinned epoxy wash coat (regardless of brand) to even it all out.

When I do final sand before wash coat, I try not to sand through, but that is almost impossible. I even it all out with the wash coat. 220 grit hand scuff before to create a good mechanical bond for finish.

Mike

I doubt much of the color is the result of the amber tint of the Z-Poxy hardener - it seems more likely that you are seeing the usual end-grain versus face-grain difference in appearance when using clear, higher refractive index pore fillers. Unlike a paste wood pore filler that reflects whatever color the pore filler has been tinted to, a clear epoxy applied to end grain mahogany acts as a light pipe, resulting in a markedly darker end grain appearance as light enters the pore and internally reflects to seeming photonic oblivion.

Mr. O'Melia is correct with regard to lighter woods such as Maple or timbers with a distinct olive/green cast like zirocote - a water-white, clear epoxy filler such as West 105/207 or (my favorite) System 3 SilverTip may be used without imparting that amber tone seen with Z-Poxy. It is also worth noting that both of those systems are blush and bloom free, so unlikely to cause trouble down the road as player perspiration or atmospheric moisture reacts with any amine salts left on the surface of the filler material. A detergent and warm water wash is the usual strategy used to remove those salts when using epoxies which may be problematic in that fashion.

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Ken Parker has a different way of doing epoxy grain enhancement - it seems to be more of a base coat than anything else. He sands the bare wood to a fairly high level (800 or so) applies his epoxy (West I believe) then removes every bit of it with paper towels - he is adamant the it all gets rubbed off. There is no sanding back between the epoxy and his finish coats.

https://kenparkerarchtops.com/archtoppery#new-page-1

I may try this next time.

Very interesting, may well try this.
Astounding sounding guitars BTW,

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The name catgut is confusing. There are two explanations for the mix up.

Catgut is an abbreviation of the word cattle gut. Gut strings are made from sheep or goat intestines, in the past even from horse, mule or donkey intestines.

Otherwise it could be from the word kitgut or kitstring. Kit meant fiddle, not kitten.

Just watched Ken parker's finishing videos and it seems to me that he's not using epoxy to fill the grain of the chestnut, but to seal it. He then applies coats of Tru Oil in the approved fashion (wipe it on and then wipe as much off as possible). He calls it linseed oil but does explain that it has other things (dryers) added to it. In the last video, a close up of the back shows that the grain is not 'filled', just sealed.

I agree with Dave, but is he also using the wetting capability of the epoxy to enhance the grain? I frequently use Zpoxy diluted with DNA on woods like maple that do not need pore filling but I want it to pop the figure like wetting it with alcohol or naphtha.

Such a great idea.

I tried a thinned zpoxy wash coat with a foam brush, but it did not flow smooth.
I ended up wiping it off with a paper towel before it cured.
I thinned it 50% with dn alcohol and cleaned the surface before applying.
Not sure what I did wrong.

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