Official Luthiers Forum! :: View topic - system three as topcoat

What are the main drawbacks to epoxy as a filler, if anybody knows?

Epoxy is something one should consider carefully, given its potential toxicity to our bodies. Sigh ... another drawback.

Filippo

Epoxy is not stable enough to be used as a topcoat. The Gougeon brothers put
much time into trying to make epoxy the one-size-fits-all in the late 70s
and 80s with their WEST system. Their conclusion thirty years ago was that
it had to be topcoated, preferably with an opaque barrier.

Mike,

I used to use... I should say 'tried to use', System 3 back in '07. I was only trying to use it as a pore filler, not as a top coat. I have not used it since for any pore filling because of its gummy after effects. I had and still use the epoxy in other woodworking applications and have no problem with the mix. I remember the very last time I used it, I applied it and waited 3 days and still had a gummy mess when sanding. That was it.

Author:	mikemcnerney [ Tue Mar 23, 2010 5:28 pm ]
Post subject:	system three as topcoat
Has anyone tried using system three as a one coat does it all finish. I'm starting to experiment with it because the idea of doing only one coat is tempting. Personaly I am interested in doing it on the back & sides only. I was just speaking with their tech support & he said to get it smooth on a vertical surface you have to brush over it about an hour after you have applied it to make sure you have eliminated any sags/runs. I asked him if you can get a thinner coat,(the normal is 3 oz. per sq ft.) and he said you have to sand the wood coarser, 100 grit. On one wenge sample I did it filled the pores & topcoated in one coat. You also have to use the torch to eliminate bubbles. Mike McNerney

Author:	Hesh [ Tue Mar 23, 2010 5:44 pm ]
Post subject:	Re: system three as topcoat
Mike another OLFer thought that epoxy would make a good finish too and tried it out with some tests, this was about three years ago. Verdict was that it's too soft, doesn't buff well.

Author:	JohnAbercrombie [ Tue Mar 23, 2010 7:10 pm ]
Post subject:	Re: system three as topcoat
What Hesh said.... Also, to apply a coat of epoxy that is thin enough to be a decent guitar finish would be quite difficult. I've used a lot of epoxy - mostly on boat projects- and I don't think it would make a good thin buffable finish. Part of the problem with application is that epoxy generally gets 'thinner' as the exothermic curing reaction gets going and the viscosity drops- so it goes on thick and then tends to sag. And, if you add much in the way of volatile solvent to it, you get a rubbery result as the solvent gasses out from the epoxy. Cheers John

Author:	TonyFrancis [ Wed Mar 24, 2010 12:35 am ]
Post subject:	Re: system three as topcoat
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Author:	JohnAbercrombie [ Wed Mar 24, 2010 1:18 am ]
Post subject:	Re: system three as topcoat
TonyFrancis wrote: What are the main drawbacks to epoxy as a filler, if anybody knows? Tony- You mean as pore filler for open-grained woods? It works quite well; I've used it a few times. Cons- It's epoxy; if you haven't used epoxy much it takes a bit of time to get familiar with it. If you leave too much on the surface you will have a lot of sanding to do. Pro- It's clear so really lets the grain show through. Cheers John

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Author:	Carey [ Wed Mar 24, 2010 6:00 am ]
Post subject:	Re: system three as topcoat
Epoxy is not stable enough to be used as a topcoat. The Gougeon brothers put much time into trying to make epoxy the one-size-fits-all in the late 70s and 80s with their WEST system. Their conclusion thirty years ago was that it had to be topcoated, preferably with an opaque barrier.

Author:	mcgr40 [ Wed Mar 24, 2010 11:48 am ]
Post subject:	Re: system three as topcoat
This is not exactly designed for instruments, but this company(it's not a big place, you can call up and talk to the guy that owns it), makes an epoxy designed to be used with their own conversion varnishes for a topcoat. kwickkleen.com This link describes what they were designing the system for. http://kwickkleen.com/exteriordoorfinishing.html He makes it for an exterior door system finish, and he is pretty nice. When I talked to him a couple of years ago, he had companies using the system to seal outdoor wooden tubs. His claim is to try and remove all wood movemnet by completely sealing all the surfaces with an epoxy he calls wood weld and then topcoating with his conversion varnish. It is just interesting, I sort of think completley inappropriate for fine instruments, but perhaps I am wrong. Lots of stuff I do not understand. It just might be of use to someone here, somehow.

Author:	Chris Oliver [ Wed Mar 24, 2010 1:51 pm ]
Post subject:	Re: system three as topcoat
Mike, I used to use... I should say 'tried to use', System 3 back in '07. I was only trying to use it as a pore filler, not as a top coat. I have not used it since for any pore filling because of its gummy after effects. I had and still use the epoxy in other woodworking applications and have no problem with the mix. I remember the very last time I used it, I applied it and waited 3 days and still had a gummy mess when sanding. That was it. good luck.

Author:	Daniel Minard [ Wed Mar 24, 2010 2:16 pm ]
Post subject:	Re: system three as topcoat
Ah, the dream of a one-step finish. I'm sure a lot of us have wished for one. I have tried both polyurethane & polyester & have been less than 100% satisfied with the results. (Neither of them is a true "one-step" system.) Polyurethane is tricky to get on thin enough & looks milky on some woods. Big leaf maple is one... (I'm not talking about the waterborne "urethane" finishes. Catylized, solvent based polyurethane, formulated for wood finishing,). I sprayed & buffed using the manufacturer's schedule & was very happy, initially. After three weeks, the pores started showing up & they kept getting deeper looking for months afterwards. Polyester & I didn't get along well at all. I kept getting fisheyes in the finish & (STILL) can't figure out why. The four instruments I finished (with much drop filling of fisheye pits) looked great. But even the polyester is sinking down into the pores after time. Oddly enough, a fine pored sappele Weissenborne is the worst. I don't know what the answer is, but I'm still looking. I am sure Epoxy is not the way to go, for the reasons noted in previous posts. I will keep on experimenting with the polyester, because I love the clear, hard finish. Just two bugs to work out. In the meantime, I am enjoying working with nitro again. Follow a few basic "rules" & it is the most forgiving finish I have found. I have resigned myself to the necessity of pore filling. Now to find a system that suits me better than what I'm using... Good luck in YOUR search for same. You'll let us know if you find that perfect one step finish. Right???

Author:	JohnAbercrombie [ Wed Mar 24, 2010 5:00 pm ]
Post subject:	Re: system three as topcoat
Chris Oliver wrote: Mike, I used to use... I should say 'tried to use', System 3 back in '07. I was only trying to use it as a pore filler, not as a top coat. I have not used it since for any pore filling because of its gummy after effects. I had and still use the epoxy in other woodworking applications and have no problem with the mix. I remember the very last time I used it, I applied it and waited 3 days and still had a gummy mess when sanding. That was it. All epoxies can generate 'amine blush' on the surface of the cured epoxy- sort of a greasy film with interferes with bonding and is also a mess to sand. (depends on temp/humidity to some extent..). In boatbuilding-scale applications, the solution is to scrub with soap and water with a Scotchbrite pad. I used probably 40? gallons of WEST epoxy and one 5-gallon jug of SystemThree on a boat project and found the SystemThree seemed particularly bad for amine blush. I've used WEST for pore filling and it seems to be OK, but then again, I try to minimize the sanding by 'squeegee-ing' the surface quite clean. So, I 'feel your pain' with the SystemThree. Cheers John

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