The shiniest finish for classical guitar back/sides

[Mike Kinny]

Hi luthiers,

What's the shiniest finish that can give a deep clear gloss look in shortest time? I've never had any luck with brushing. Brush marks are always visible. French polishing takes waaaay too long. However wiping on thinned lacquer is what I've found best so far. Never tried spraying. Maybe I try spraying thinned lacquer.

What about 2 component poly finishes?

Thanks

[Barry Daniels]

The shortest time? Probably UV cured polyester.

[John Clifford]

Purists, and even not-so-purists, might have a problem with a poly finish on a classical guitar.

[David King]

Polyester finish should cure hard in 12-24 hours using cobalt and MEKP so UV curing doesn't save you that much time in the grand scheme of things. While polyester sands out very easily it is more time consuming to buff. Automotive refinishing 2k and 3k polyurethanes are less scratch resistant but they buff to a very high gloss with less effort and at a lower buffer speeds. You get what you pay for and you'll get stuck with buying way more than you need. I'd start with a couple-three spray cans of Mohawk clear nitrocellulose lacquer and see how that goes. Lacquer takes a month -6 weeks to cure. 2k and 3k polyurethanes take about a week or two to where they won't imprint but they can keep on shrinking for a month or more.

[Alan Carruth]

I saw a demo of the Glu-Boost finishing system, based on their (mostly) odorless CA, that may be what you want. You spread on the gel and hit it with their special 'kicker' which hardens it more or less instantly, without blushing. Sand flat and repeat a few times until you have the thickness you want. Since it's a gel that doesn't take many coats. It seemed to sand easily, and buffed out nicely.

I'm still sticking with oil-resin varnishes.

[Mike Kinny]

Purists, and even not-so-purists, might have a problem with a poly finish on a classical guitar.

I have no problem with anything at all. lol

[Clay Schaeffer]

The more I try to "rush" the finish, the longer it ultimately takes. For "shiney" you will need to spend more time on prep work. "Shiney" shows all the scratches and mole hills. If you are only doing one, David King's suggestion of using Mohawk spray can lacquer might be the way to go.

[Christ Kacoyannakis]

Clay, I totally agree. The tendency, at least for me, is to get all the building done, and then be really excited to get the finish done, and put the strings on. I have to really force myself to slow down, do the extra day of sanding, the three pore filling treatments, and then the sanding sealer, and finish. Then waiting the appropriate time for the finish to cure is interminable! I suppose if you are using a 2K finish that is pretty quick. However I am using more conventional finishes, and everybody whose work I have admired has said that waiting that extra amount of time (the more, the better) has yielded a much better finish, that buffs out better.

[Mike Kinny]

The more I try to "rush" the finish, the longer it ultimately takes. For "shiney" you will need to spend more time on prep work. "Shiney" shows all the scratches and mole hills. If you are only doing one, David King's suggestion of using Mohawk spray can lacquer might be the way to go.

Intending to do the pore filling with Z-poxy.

[Brian Evans]

I would try wiping or brushing Brite-tone for a quick, fairly easy gloss finish. Put down 6 coats, let dry one day, sand flat to around 800 grit, 4 more coats, let cure for three days so it cross-links, wet sand and polish as normal for any lacquer. Brite-tone is a water based, pre-catalyzed cross-linking gloss lacquer specifically designed for instruments. The pre-catalyzed, cross-linking bit means that after several days it undergoes a chemical change that makes it very hard and tough, suitable for wet sanding and polishing to a high glaze.

[Steve Sawyer]

I'm going to second Brian's recommendation of Brite Tone. I'm getting close to putting the finish on my second build, and will be starting my second test board tomorrow. My first test board came out absolutely flawless after brushing 8 coats of Brite Tone on top of a pore-fill of System Three Silvertip. It levels beautifully. I didn't do any level-sanding until the eight coats were down, starting at 800, continued wet-sanding up through 2000, then polished.

The only reason I'm doing a second test is that 1) I had a small sand-through on the first test, and want to do another test with 12 coats instead of 8, and 2) I want to test this finish with a slide-on decal. The decal maker recommends using a rattle-can spray enamel to "embed" the decal before applying finish over it. I want to determine if I can get away with a thin coat of Brite Tone, or if the water in the finish softens and lifts the decal. The decal maker suggests spraying a mist coat over the decal, but I neither have spray equipment or a space in which to use it, so I'm going to try just a quick wet swipe of Brite Tone and see what happens.

[David King]

You might also consider coating with a specialized coating epoxy like West System's wooden boat coating 105/207 which includes a UV inhibitor. I use this as a filler and find that it sets up very nicely after 8 hours and sands really well too. It can be buffed after just a few days to a very high gloss with a nice amber tint. If time is your limiting factor then applying two coats of epoxy (brushed or rolled) with light sanding between them and a careful level sanding and buffing can't be beat and you can always add another finish over it later (except for polyester).