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I've been using Zpozy for a few years now and really like the stuff as a pore filler. I'm at the finishing stage on 3 guitar bodies. All B&S have been pore filled with Zpoxy and sanded to 400 grit. On the EIR in particular it almost looks like I could wet sand to a high luster and I'm seriously considering doing just that. In reality, I would apply one or more light coats to make sure that I don't wet sand and buff through. The top will be French Polished.

My questions are:

1) Has anyone done this?

2) How hard (scratch resistant) is cured Zpoxy compared to Nitro?

2) What long term aging characteristics should I expect as to cracking and crazing? I understand that instrument grade Nitro has some inherent flexibility to allow it to expand and contract with humidity changes and was wondering if the epoxy would behave similarly.

I'm hoping to get some feedback before taking the plunge. I figure that even if it doesn't work out I can always sand back and apply nitro, so I feel that I have an acceptable escape plan.

Soooo....whaddya think? Post quickly if there's a fatal flaw in my rationale...I'll be starting this before the weekend!

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JJ
Napa, CA
http://www.DonohueGuitars.com

Hey JJ, check out the spec sheets on the toxicity of epoxy and see if you really want to do that. Epoxy is nasty stuff - probably as bad or worse than nitro, and definitely even worse when you're talking about the dust from sanding it. Make sure you use a really good respirator with organic vapor cartridges...

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JJ,

I've had the same thoughts - Z-Poxy is a finishing resin after all. I'd be inclined to do your own tests on some scrap first in terms of seeing what happens when you scratch and how easy a repair is - I suspect not hard although there may be issues of colour matching if the repair goes through to bare wood first. Also see how well it wet sands. The other thing I would test is how it takes to fingermarks etc and how easily it cleans up from these.

To me it seems a very hard finish and I suspect it is at least as flexible as nitro.

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Dave White
De Faoite Stringed Instruments
". . . the one thing a machine just can't do is give you character and personalities and sometimes that comes with flaws, but it always comes with humanity" Monty Don talking about hand weaving, "Mastercrafts", Weaving, BBC March 2010

[QUOTE=Don Williams] Hey JJ, check out the spec sheets on the toxicity of epoxy and see if you really want to do that. Epoxy is nasty stuff - probably as bad or worse than nitro, and definitely even worse when you're talking about the dust from sanding it. Make sure you use a really good respirator with organic vapor cartridges...

[/QUOTE]

Don,

You are right but those same precautions should also be taken when treating it as a pore filler as lots of builders do now and have done for a while now. If I were going to experiment with this as a finish I wouldn't be looking to build up many coats more than are currently used in the pore filling process. Full buffed out shiny is not what I go for anyway, but you can get a pretty good looking finish from the 2-3 coats that go on for pore filling.

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Dave White
De Faoite Stringed Instruments
". . . the one thing a machine just can't do is give you character and personalities and sometimes that comes with flaws, but it always comes with humanity" Monty Don talking about hand weaving, "Mastercrafts", Weaving, BBC March 2010

I don't know if you could get a good polish on it, you might be able too. I think as a nice satin finish on the back ans sides, it would work great and match that FP top nicely.

Epoxy is used for top coat finish on food contact surfaces and medical devices. The cured form is safe. You do want to be careful with it in dust and liquid form, especially the hardener. Never spray epoxy. As epoxy leaves a spray gun nozzle, it is reduced to tiny droplets (spray mist). You can easily inhale epoxy that is suspended in the air. It can cause extensive lung damage and other health problems. The spray mist can settle on your skin, causing sensitization and allergic reactions. It can settle on your eyes, injuring them.

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Don...Why organic vapor cartridges. This is a reactive material, not an evaporative. I don't think volatiles are the issue... I think the sanding dust is the main culprit. One of the things I've always done when using Zpoxy is to scrape most of the stuff off with a cabinet scraper and then sand off the remainder. It minimizes the amount of dust generated. Nonetheless, I use a dust mask when sanding.

Hesh...Fish Eyes! The only time I ever saw a fish eye was on the end of a hook. Seriously, it is my understanding that fish eyes occur when there is a contaminant on the surface and it prevents the finish from adhering. In that case, I would have seen some at this point in the process. Correct me if I'm wrong because I haven't experienced one with any finish...yet

Well normally I take a conservative approach and do testing before jumping in. This time, I went in head first aabout an hour ago and laid down the first additional coat of probably 3 coats. I may be wet sanding by the weekend. What better way to test the hypothesis than on an actual guitar. Since it will reside in the family, I'll have the opportunity to watch it grow old. If it looks awful, I'll sand it back and spray lacquer.

Wish me luck....in the meantime, I AM testing the effect of tinting shellac for the tops.

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JJ
Napa, CA
http://www.DonohueGuitars.com

[QUOTE=Don Williams] Hey JJ, check out the spec sheets on the toxicity of epoxy and see if you really want to do that. Epoxy is nasty stuff - probably as bad or worse than nitro, and definitely even worse when you're talking about the dust from sanding it. Make sure you use a really good respirator with organic vapor cartridges...

[/QUOTE]
It's always best to err on the safe side, and the toxicity may vary from brand to brand, but....
The epoxies I've used (WEST, System3) are reputed by the manufacturers to be quite safe from the 'organic vapor' standpoint, especially after curing. Cured epoxy dust is probably no more (or less) dangerous than wood dust, especially from some of the exotics folks are using for guitars. A good dust mask is what I've used when sanding anything.

The epoxy hardeners are fairly nasty, but the viscosity is high and vapor pressure fairly low so it takes a lot of effort to get much airborne.

You can assume the usual USA legal disclaimers follow here.....best to err on the safe side etc etc

John

I think that the bare epoxy will be UV sensitive and should be topcoated if it will see direct sunlight.

Al

Al...do you think it would be any more UV sensitive than Nitro? Is the effect just color shift...or worse?

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JJ
Napa, CA
http://www.DonohueGuitars.com

re:UV sensitivity of epoxy.
Al is right- if your guitar will be exposed to direct sunlight (outdoors) for extended periods of time (think many bad sunburns for you) then it should be topcoated with something with lots of UV filtering - a nice dark spar varnish or similar.
Indoor (filtered through glass) sunlight will not break down your epoxy film very quickly, if at all. If you take decent care of your instruments- don't leave them in a sunny window or out on the deck for days at a time, I wouldn't worry.
BTW, UV will make epoxy turn translucent and then 'chalk'- not a pretty sight. This is an issue for boats, and the reason that sensible folks don't leave their strip-built kayaks on the roof of the car for weeks.
John

I think an epoxy finish would dampen acoustics. Much more so than nitro lacquer.

[QUOTE=BarryDaniels] I think an epoxy finish would dampen acoustics. Much more so than nitro lacquer.[/QUOTE] Barry,
I'm trying to understand why you would say that it would be dampening. Please fill me in. I'm not trying to be argumentative, just trying to learn. Is this something you know from experience?
Thanks!

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"An adventure is only an inconvenience rightly considered. An inconvenience is an adventure wrongly considered." G. K. Chesterton.

Barry...I first wondered about that myself. I decided that it was a good bet to try for two reasons. The cured Zpoxy seems to be very glass-like...much like HHG. It doesn't have a soft and malleable surface which I believe would dampen sound. The second reason is that the thickness when sanded and buffed out should be no greater than that of a nitro finish...at least that's what I'm shooting for.

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JJ
Napa, CA
http://www.DonohueGuitars.com

When I use epoxy as a pore filler, I sand back to bare wood and attempt to leave epoxy only in the pores. I think it is easier to control the thickness of a sprayed nitro finish than a layer of epoxy, that would be one of my concerns if I thought about using it as a finish.

A small sidetrack: I am getting ready to fill my first instrument with Zpoxy now (I have used locally available epoxies until now), and I see people recommend leaving a thin layer of epoxy under the topcoat. As I understand it this is to avoid blotches if you sand back to bare wood in spots later as the Zpoxy has some color. Is there a problem with sanding back and leaving this particular epoxy only in the pores of the wood like I usually do (other than reopening pores if I am not careful)?

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Rian Gitar og Mandolin

[QUOTE=JJ Donohue] Don...Why organic vapor cartridges. This is a reactive material, not an evaporative. I don't think volatiles are the issue... I think the sanding dust is the main culprit. One of the things I've always done when using Zpoxy is to scrape most of the stuff off with a cabinet scraper and then sand off the remainder. It minimizes the amount of dust generated. Nonetheless, I use a dust mask when sanding.

[/QUOTE]

JJ, I would wear the vapor cartridges. Many epoxies use an Amine curative and these aren't really good for you.
-jim

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Jim Watts
http://jameswattsguitars.com

Think about this. If you pore fill with epoxy then sand back to bare wood except for the pores, followed by a thinned wiped coat, let it cure then polish. It seems to me that You have a nice thin finish that would be identical to what we use for our lacquer base minus the thickness and weight of the lacquer.
Has anyone tried to polish bare epoxy?

Al

Good question Al, i too would like to hear about that since the same thought crossed my mind when i pore filled no 2.

[QUOTE=A Peebels] Think about this. If you pore fill with epoxy then sand back to bare wood except for the pores, followed by a thinned wiped coat, let it cure then polish. It seems to me that You have a nice thin finish that would be identical to what we use for our lacquer base minus the thickness and weight of the lacquer.
Has anyone tried to polish bare epoxy?

Al[/QUOTE]

Stay tuned...I'll let you know all about it this weekend.

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JJ
Napa, CA
http://www.DonohueGuitars.com

Z-Poxy makes both a laminating/pore filler epoxy and a finishing resin. It seems the finishing resin should buff to a very nice shine.

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Thank You and Best To All

We use the Finishing Resin for pore filling...go figure

That's what I'm thinking as well. Having used it for pore filling and noticing how hard a surface it cures to and how smoothly it sands, I just have to try it on a guitar.

It could be a lot of work for nothing but I think it's worth a try.

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JJ
Napa, CA
http://www.DonohueGuitars.com

I will be interested to hear your results JJ

Mike

I guess the only question may be how will it stand up to the polishing. If you have a power buffer, I wonder what a little bit of heat will do? Will it react the same as nitro, have the same heat restiveness (is that a word) as nitro, although I know it's really not that high.

I guess I'm saying just watch the buffing. Cool Idea JJ, good on ya to take the bull.........by the horns

I'm certainly interested in the results. It would certainly cut down on the finishing time for nitro and the required explosion proofing for finishing.

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You still need another finish for the top.

I tried buffing epoxy once and it didn't give me a very good shine. I did like it with a couple of coats of true oil on top. Lots of pop but not too shiny.

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