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Living in Hawaii is like living in another universe when it comes to being able to see other peoples work. Very few builders and not many experienced builders to share info with. I've been spraying nitro for about 45 years, and it still is never easy. I've seen plenty of posts here about Z-poxy, but never really looked too close because I tried epoxy a couple of times and never would again. I do nitro on top of shellac with miserable waterbase fillers in-between. Works great, but it's a grueling process to get a fully filled surface. Last weekend I saw an instrument with Z-poxy under nitro. The builder was not great at finishing, but it looked like there was potential. He said it was easy to sand, being a resin that is different than an epoxy like West System or System 3.I would be interested in hearing about a successful finish routine using Z-poxy and nitro, if anyone has one, before I order the stuff to try. Thanks, Bob

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“ The meaning of life is to find your gift and the purpose of life is to give it away” Pablo Picasso

Before I started building guitars, four so far, I'd built a large number of r/c sailplanes, all finished with z-poxy surfacing resin.
Working with epoxy allows someone to feel as if he's auditioning for The Sorcerer's Apprentice, but patience, preparation, and neatness help no end. And disposable gloves.

In guitar building, I brush on a coat of z-poxy and squeegee off all I can (those old credit cards come in handy). And the brush is sacrificial, use once and discard. No globs, no buildup. please. Sleep on it, come back the next day and block sand. Do it again. Wipe on a third application, to make sure that I haven't sanded down to bare wood anywhere. And proceed with the lacquer after an overnight set and touchup sanding. I apply the z-poxy without thinning, and I see a pot life of about twenty minutes before it starts to set up. Any thinning I do is with heat (pot of hot water), not anything mixed into the epoxy. I mix in disposable medicine cups (think cough syrup). Don't need much. Start with 20cc total and see how far that goes.

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Peter Havriluk

I use Z-poxy as pore filler, but not under nitro so I can't address that specifically. The one thing to be aware of is that you have to use it at temperatures above 69 degrees or it won't cure properly. Probably not a problem where you are unless you air condition your shop a lot, but I thought I would mention it.

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Once in a while you get shown the light in the strangest of places if you look at it right - Robert Hunter

While YMMV, I've been applying Z-poxy in a 62-degree-fahrenheit basement quite successfully. The box specifications do mention a desired temperature, but my experience has been that the box instructions are conservative. I DID hang my guitar body near the heating plant, but I also left the mixing cup in the 62-degree area. Both set solid. And I agree that the manufacturer's instructions need respect, but testing will set each user's limits in that user's work area.

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Peter Havriluk

Bob, I have tried them all including water Bourne fillers,zpoxy etc. i have settled on system 3 112 resin epoxy. I measure by weight and fill pores in two coats, sometimes 1. I always use nitro. I use a razor blade and don’t sand back to wood. I leave an epoxy coat on my gits as base. I find I use much less nitro and have fine enough finishes. I don’t use epoxy in the necks. Too many curves. On necks I use a Sherwin Williams oil based pore filler that only comes in gallons. It wasn’t cheap but a gallon goes a long way on necks. I don’t have pores showing up years later. I don’t remember the part number of the SW product but it’s not something in the stores it has to be ordered. With these products I don’t find finishing to be difficult. The zpoxy, I quit due to it not getting as hard as system 3 and it has a darker tint. I am settled on these products.

I would avoid bushing epoxies such as Z-Poxy in humid environments. System 3 SilverTip was recommended by well known Portland, OR based builder John Greven after he trialed it against other materials and had several hundred instruments in customer hands finished with SilverTip and Enduro-Var. For us the material proved trouble-free, with the side benefits of perfect viscosity for filling work and zero color change. Z-Poxy adds a pronounced amber tint to filled woods which are not fully sanded back, so is problematic on some woods.

If tint is desired in clear epoxy fillers, it is easy enough to use TransTint honey amber dye from a calibrated pipette (a laboratory tool which is useful for mixing up color recipes...even inexpensive ones are much better than the disposable poly models used for CA or other non-volume critical workshop chores).

Mixing SilverTip is easily done in small quantities with a 0.01 capable gram scale (the type suitable for cartridge reloading)...if the scale allows both gram and grain (usually abbreviated gn), it will work for mixing epoxies in batch sizes down to 5-6 grams.

Other issues: we saw nitro finish separation on a handful of Z-Poxy instruments (including two of our own) caused by what we believe were trace amounts of amine salts (blush products) reacting to lower pH player perspiration. These issues moved us away from any epoxy fillers with chemistries that may see blush or bloom reactions and not called out by the manufacturer as blush/bloom free in normal use.

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For the times they are a changin'

- Bob Dylan

I used Z-Poxy one time and wasn't happy, lots of shrink-back. A respected builder told me about Silvertip, no blush and no shrink-back especially under the heat of power buffing.

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It will probably be alright.

I use zpoxy almost exclusively under nitro. I use it for both pore filling on porous wood like rosewood or coco or koa and for highlighting grain on highly figured wood (and often both). I have also used it under water born lacquers but I'm mostly back to nitro. I need to stress that I am strictly an amateur builder and finisher and I'm still very low on the learning curve







I even did a little description of how I use it for another forum, I could link that for you if you would like.

Obviously your results may vary and like any other finishing topic you should practice on scrap.

Thanks for all the replies. I think my best pore fills were 40 years ago when Martin used to supply me with their Naptha based colored fillers. Working mostly with koa, the wide variety of wood colors that are on a single instrument, made me change to clear fillers. My current shellac/Aqua-Coat/nitro schedule does the job, but can be maddening. Every new change in products means a new opportunity for disaster.The problem I had with epoxy fills was the sand through issues. After seeing the comment about the tint that Z-poxy adds, I'm more inclined to try the System 3. Taking into account all the reply info here, I think I'll have another go at it. Thanks, Bob

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“ The meaning of life is to find your gift and the purpose of life is to give it away” Pablo Picasso

I have been using epoxy for pore fill for many years. I started with Zpoxy but now I use System 3 Clear Coat, Unless I'm looking for a little amber in the finish. Then I still use Zpoxy. Overall I like Clear Coat better. The advantages are, no amine blush, thinner, making it easier to end with a thin finish. Early on I used it under waterbased. Currently, I use Cardinal Luthierlac and their vinyl sealer.

I use this schedule for the epoxy. It is geared toward as thin a coat as I can get.

I wipe the guitar down with DNA, then I warm a section at a time with a hairdryer, (as in the back or one side, or the neck). This drives the moisture out and makes amine blush (a Zpoxy issue) unlikely in all but very humid conditions.

Once I warm one section I proceed with the epoxy. I spread a thin layer of epoxy with a plastic spreader followed by a squeegee. Then I immediately warm the just applied epoxy with the hairdryer, being careful not to get it too warm. If it does it can easily bubble which is bad, then I lightly brush it once with a good quality foam brush. (Not the Home Depot variety) This will pick up excess and smooth ridges. You don't want to go back over it with the brush or re-heat. It will be a mess

I let the first coat dry just until it can be handled without imprinting, usually 4 hours depending on conditions. Then I repeat the same way except I skip the DNA and the first 'warm-up'.

I continue on, trying to get two or three coats as needed, in one day. The reason you don't want to let it cure to much between layers is then you will end up with a mechanical bond, instead of a chemical bond (cure) between layers. Done this way the epoxy will be thin and smooth requiring less level sanding.

I let it cure for 7 days followed by level sanding, depending on conditions. The warmer the guitar is during the cure period, the quicker it will be.

Here is what a koa guitar with System 3 Clear Coat and Nitro would look like:

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Joe Beaver
Maker of Sawdust

I use Z-poxy under lacquer.
First grain filler I tried that actually filled the grain.

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Freeman,
Great looking stuff there!!!

Dan,
I sure like that guitar. Is that some kind of ebony?

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Joe Beaver
Maker of Sawdust

[quote="Joe Beaver"]Freeman,
Great looking stuff there!!!

I was going to say the same thing about Dan's guitar, but I don't know anything about guitars. But I know off the wall cool!

I did use Z-poxy to finish the one Archtop I made. The only problem that I had is that my basement is 50 degrees in the winter. I put the bottles of resin and hardener on the heat register, heated the body up with a heat gun, and it worked. It worked great as a fill; I even used it like an old fashioned mastic on my inlay around the edge. It even worked well with a couple dabs of oil paint mixed in to push the color towards red-orange. Oddly, it did that by adding Azo Green.

I might use it on the Walnut/Alaskan Yellow Cedar violin I'm making. The Walnut needs fill, and I know it works.

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Why be normal?

I love Z-poxy. I've been using it for the last decade and haven't had any issues using the recommended sealer between it and my topcoat. It pops the grain like no other.

Thanks!
Some kind of Ebony and Koa veneer.

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