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PostPosted: Sat Apr 03, 2021 10:33 am 
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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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PostPosted: Sat Apr 03, 2021 11:13 am 
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Brazilian Rosewood
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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.



These users thanked the author Clay S. for the post: dzsmith (Sat Apr 03, 2021 1:32 pm)
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PostPosted: Sat Apr 03, 2021 11:13 am 
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Brazilian Rosewood
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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

Attachment:
IMG_4723-1.jpg


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.

Attachment:
IMG_4725-1.jpg


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These users thanked the author Freeman for the post (total 2): Colin North (Sat Apr 03, 2021 5:15 pm) • dzsmith (Sat Apr 03, 2021 1:32 pm)
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PostPosted: Thu Apr 08, 2021 3:44 pm 
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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



These users thanked the author Mike OMelia for the post: dzsmith (Sun Apr 11, 2021 4:09 pm)
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PostPosted: Mon Apr 12, 2021 8:19 am 
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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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These users thanked the author Woodie G for the post: dzsmith (Mon Apr 12, 2021 12:10 pm)
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PostPosted: Mon Apr 12, 2021 11:46 am 
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Brazilian Rosewood
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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.



These users thanked the author Freeman for the post: dzsmith (Mon Apr 12, 2021 12:10 pm)
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PostPosted: Tue Apr 13, 2021 3:49 am 
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Freeman wrote:
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.


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PostPosted: Tue Apr 13, 2021 12:47 pm 
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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.


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PostPosted: Thu Apr 15, 2021 11:18 am 
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Brazilian Rosewood
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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.


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PostPosted: Thu Apr 15, 2021 2:56 pm 
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Freeman wrote:
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.


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PostPosted: Thu Apr 15, 2021 5:55 pm 
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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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