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Sprucing up a poly finish?
Posted: Fri Nov 07, 2008 5:42 am
by kiramdear
Hope I'm not duplicating another discussion ... I'm looking into optimizing the sound and look of my '04 Korean Epiphone Sheraton. Looks like it's going to stick around
Two threads, actually:
Does a poly finish inherently change the sound of an electric acoustic's amplified sound for, what some would say, the worse as opposed to a vintage finish? Would my guitar
sound better with a refin?
Is there a way to make a poly finish look better, short of engaging in relicking

Poly has its pros in that it is tough, water resistant, etc., a clear virtue for any guitar in my hands for any length of time. But I don't like the glassy look as well as I would a breathier look and feel.
Is there some mildly invasive process by which a shade-tree mechanic like me can achieve a little more sensitive effect for the finish of this beautiful hollow wooden guitar? Not necessarily to strip it but to cosmetically improve its look and possibly sound (if that's a consideration). The ebony paint job underneath is completely opaque; there's no sign of any grain even with a strong light shone from within. The paint job is quite perfect to my eyes

but the glazed finish kills the thrill a bit, you know?
Thanks for input.
Re: Sprucing up a poly finish?
Posted: Fri Nov 07, 2008 1:41 pm
by jingle_jangle
kiramdear wrote:Hope I'm not duplicating another discussion ... I'm looking into optimizing the sound and look of my '04 Korean Epiphone Sheraton. Looks like it's going to stick around
Two threads, actually:
Does a poly finish inherently change the sound of an electric acoustic's amplified sound for, what some would say, the worse as opposed to a vintage finish? Would my guitar
sound better with a refin?
Is there a way to make a poly finish look better, short of engaging in relicking

Poly has its pros in that it is tough, water resistant, etc., a clear virtue for any guitar in my hands for any length of time. But I don't like the glassy look as well as I would a breathier look and feel.
Is there some mildly invasive process by which a shade-tree mechanic like me can achieve a little more sensitive effect for the finish of this beautiful hollow wooden guitar? Not necessarily to strip it but to cosmetically improve its look and possibly sound (if that's a consideration). The ebony paint job underneath is completely opaque; there's no sign of any grain even with a strong light shone from within. The paint job is quite perfect to my eyes

but the glazed finish kills the thrill a bit, you know?
Thanks for input.
The only things these have in common are that they are catalyzing topcoats and that they are sprayed.
This frustrates me a bit, Kira, because "poly" is not a useful finish term, seeing as there are several types of "poly", at least two of which are used on guitars. These are poly
ester, and poly
urethane..
Since this is a Korean guitar, I'd say it's probably finished in polyester. This, BTW, is essentially the same material that's used as the liquid portion of a polyester composite (aka "fiberglass") structural system, fine-tuned for tough-skin properties instead of "wetting out" properties.
Polyester is TOUGH to remove. If you're committed to removing this finish, try using a bit of paste chemical stripper ("Zip-Strip" or the like), on a small area. If the finish blisters and wrikles, it's likely poly
urethane, which will chemically strip. If the finish merely swells, it's going to be a tough battle. Put some John Lee Hooker on the stereo and get out the coarse sandpaper (80 or 100 grit). It will take about a day of sanding, and after all the paint is off, you can final-sand with #150 and then #320 to get it nice and smooth again. The top and back of this guitar are gonna be pressed plywood, so be careful not to sand through the top layer of veneer into the cross-ply underneath.
Final finish: If it's tone you're after, thin, clear nitrocellulose is a good bet. You could also try shellac, in several coats, sanding between them with #320, and final coat put on with a gauze mop. See "French Polishing" in your Google dreams...and don't inhale the fumes or dust!
Re: Sprucing up a poly finish?
Posted: Fri Nov 07, 2008 2:40 pm
by kiramdear
jingle_jangle wrote:Since this is a Korean guitar, I'd say it's probably finished in polyester. This, BTW, is essentially the same material that's used as the liquid portion of a polyester composite (aka "fiberglass") structural system, fine-tuned for tough-skin properties instead of "wetting out" properties.
I thought it felt to be an ominously familiar material.
jingle_jangle wrote:Polyester is TOUGH to remove. If you're committed to removing this finish, try using a bit of paste chemical stripper ("Zip-Strip" or the like), on a small area. If the finish blisters and wrikles, it's likely polyurethane, which will chemically strip. If the finish merely swells, it's going to be a tough battle. Put some John Lee Hooker on the stereo and get out the coarse sandpaper (80 or 100 grit). It will take about a day of sanding, and after all the paint is off, you can final-sand with #150 and then #320 to get it nice and smooth again. The top and back of this guitar are gonna be pressed plywood, so be careful not to sand through the top layer of veneer into the cross-ply underneath.
Final finish: If it's tone you're after, thin, clear nitrocellulose is a good bet. You could also try shellac, in several coats, sanding between them with #320, and final coat put on with a gauze mop. See "French Polishing" in your Google dreams...and don't inhale the fumes or dust!
Thanks, Paul. Your comments indicate to me a good course of action. My first question regarding tone was the important one so eventually i'll look into getting a pro refin in traditional materials.
The other half of my concern was to find an easy way to just maybe knock down the gloss level a bit on the existing finish without completely removing it and the nice paint job. Any heavy hand work is out of the question for me, sadly. Could it easily be made to appear a little more satin, at least, meantime ?
Re: Sprucing up a poly finish?
Posted: Fri Nov 07, 2008 3:29 pm
by deaconblues
I guess you could try to concoct some of that VOS gunk Gibson puts on reissues...it will rub off over time, but it takes the super-shininess off.
Re: Sprucing up a poly finish?
Posted: Fri Nov 07, 2008 3:53 pm
by jingle_jangle
Regarding making this satin, and assuming you might go for a pro refin at some time in the future, I'd say this: first, carefully go over the entire guitar's shiny areas with some #me fine Scotch-Brite to scratch it up well. There should be no gloss showing anywhere. I'd at least remove the guard, TRC, tuners, knobs, and tailpiece, and probably the strap pins and any other hardware that gets in the way of the scuffing process. You can leave the pickups in place; just carefully mask them off. Mask off the fretboard, too.
You can then pick up a can or two of satin-finish clear nitrocellulose lacquer at a hardware or paint store (that big place on Second in San Rafael might be a good source). Minwax, Valspar, and Ace are three brands, out of dozens possible. But it must be lacquer. If it doesn't say so on the can, it won't be good for this use.
Dust on light coats (maybe 30% coverage per coat) from about 6" away. Don't load it on, and wait a few minutes between coats.
Re: Sprucing up a poly finish?
Posted: Fri Nov 07, 2008 4:01 pm
by kiramdear
Ah, now were talking about something I can do. Besides, I don't want to have it unavailable for any great length of days. That's great.
Circular pattern with the scotchbrite, Paul?
Thanks
Man, this guitar sounds so much like Hooker's it makes me hoot!
Re: Sprucing up a poly finish?
Posted: Fri Nov 07, 2008 4:06 pm
by jingle_jangle
kiramdear wrote:Ah, now were talking about something I can do. Besides, I don't want to have it unavailable for any great length of days. That's great.
Circular pattern with the scotchbrite, Paul?
Thanks
Man, this guitar sounds so much like Hooker's it makes me hoot!
Forgot to mention...NOT circular. Straight strokes, binding and all.
Re: Sprucing up a poly finish?
Posted: Fri Nov 07, 2008 4:31 pm
by kiramdear
Being a boater, I'm intrigued about your mention of shellac, one of the very best wood sealers. It can also be quite stunning in appearance. Here's a very good link to a site about French polishing and shellac.
http://www.milburnguitars.com/fpbannerframes.html
Re: Sprucing up a poly finish?
Posted: Fri Nov 07, 2008 6:34 pm
by jingle_jangle
That's the best tutorial I've seen online, Kira. Interesting...what I call a "mop" (the pad shaped like a pounce, used to apply the alcohol/shellac/olive oil mix to the instrument's body), they call a "muneca"--and I think they mean "muñeca", but didn't know how to get a tilde in Win. Of course, this is Spanish for "doll", which would kind of figure, because French polishing is more common to classical guitars than other methods. And the little muñeca does look like the head of a rag doll...
Anyway, it's in my "Favorites" now.
Re: Sprucing up a poly finish?
Posted: Fri Nov 07, 2008 6:53 pm
by kiramdear
I just got back from picking up supplies, so I'll let you know how it goes.
Re: Sprucing up a poly finish?
Posted: Fri Nov 07, 2008 10:17 pm
by johnallg
Kira, did you read the FAQ page? About the vulnerability of the fp finish to easier wear? Something to consider.
Re: Sprucing up a poly finish?
Posted: Sat Nov 08, 2008 4:29 am
by kiramdear
I wasn't planning to do the french polish on this guitar, that being one good reason.
But I just finished with the satining and I'm very pleased with the appearance. I used Deft satin wood finish lacquer. It now has the finish like the Epi Dots that I like so much. Satiny gloss, clean and soft to the touch and eye. Take a look:

The photo is a little blurry without flash but it shows that I got the look I wanted. I was very careful and observant during the spraying and buffed it softly between coats and it came out first class
Thanks to all for your input.

I'll be just fine with this satiny look until I can have a really nice job done of it with the good materials.
Re: Sprucing up a poly finish?
Posted: Sat Nov 08, 2008 6:43 am
by antipodean
Looks good Kira!
Re: Sprucing up a poly finish?
Posted: Sat Nov 08, 2008 1:33 pm
by jingle_jangle
Nice job, Kira! Note that it will begin to show gloss in areas of heavy wear, though.
Re: French polish...anyone who's owned a French-polished antique table will know the heartache of condensation rings from glasses aving been left on the top. This is not rocket science to repair, but the repair needs to be done by someone who knows their beans re: FP.
French polish is far from waterproof. I'd say, "water-resistant" is a better description. I'd use it on a classical only, I think, and then I'd treat it with kid gloves. It is the thinnest finish you can apply, however.
Re: Sprucing up a poly finish?
Posted: Sat Nov 08, 2008 1:54 pm
by kiramdear
jingle_jangle wrote:Nice job, Kira! Note that it will begin to show gloss in areas of heavy wear, though.
Thanks, Paul. I surprised myself how well it looks. Just like those Epi "Dot" satin finish, but a little more faded and thinner looking. No orange peel either

I stopped short of really flooding it, just till the scuffing marks were gone and the surface was
almost completely unified.
I'm already seeing signs of "buckle burnish", but that's fine. As I said, if I still like the guitar in a few months I'll have a good job done of a real lacquer finish. This is all for vanity, really, as I detect no change in tone.
So I got no excuse not to lay down some heavy tracks today
Thanks for free lessons, Paul
Thanks, too Evan
p.s. the mother of pearl flowerpot shows a
lot more color when seen through a satin finish. Wow! Twice as colorful as before
