Spruce top, maple sides, oak fretboard, maple neck.
Trying to choose a clear finish that will preserve the wood, especially the spruce top... would prefer to use the same finish on everything...
Thoughts?
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I couple coats of Danish Oil followed by a few coats of Minwax Satin Lacquer, which has the best spray tip and the smoothest end result. The Minwax alone works great on paper boxes.
Here are a few of my builds:
http://lumberjocks.com/projects/299738
http://lumberjocks.com/projects/292706
http://lumberjocks.com/projects/306994
Not knowing any better, all my builds have been finished with a very high quality marine varnish, at least three coats and usually more, with fine sanding between coats. I think you likely remove at least one half of each previous coat when sanding. I do the insides (only one coat) too before assembly, under the reasoning that this helps prevent humidity absorption. Sometimes I spray, but honestly, I can get a beautiful wet glassy look with just a foam tipped brush too, so lately I haven't bothered to get out the spray gear since I dislike the spray cleanup process so much.
Maybe the varnishing is bad for the acoustic quality, but to my admittedly untrained ear all my guitars have sounded great to me, and the ones who have ended up with them say the same thing. I'm sure I will hear from some people with very good technical reasons why varnish is wrong, but if the ancient masters used it, I feel it should be quite acceptable now for amateur me.
Here's my process: The first coat is a severely thinned back application, meant to penetrate and seal the wood. Then a light sanding down to 400 grit, then re-coat two to four times with a good thorough sanding with 400 between coats.
The varnish: I use Epiphanes high-gloss marine varnish, purchased from Jamestown Distributors in Rhode Island. They offer two to four day shipping in the US. After the first opening and use out of the can ALWAYS strain any further use from an open can. You can buy paint strainers at Home Depot by the box of one hundred for about twice the price of one of the little blister packs of three or five.
Additive: I use 'Penetrol' oil which is widely available through most paint and hardware stores, usually adding about 15-30% by volume. This is a rather thick 'thinner', used for its 'flowing' effect rather than as a thinner. This will cause the varnish to 'flow out' like glass;
The actual thinner: sometimes, especially in warm weather, the varnish will be too thick, even with Penetrol, and tend to sag in places. Use mineral spirits - the real thing, and not that pretend 'no odor' kind to get the right consistency. You will need to experiment a little to find just the right mix. After you learn, you will be able to judge by how the stirred varnish drops off your stir stick. Once you nail that you will know!
I hope this helps.
Gnarly
Great advice and information! Thanks!
My latest go-to has been a rattle-can of spray shellac quick and easy and dries fast.
and yes the finish does impart character to the tone and timber, the search is still on for the secret formula that Stradivarius used
There's no more a mistery behind Stradivarius' lacquers, check «Secret behind the composition of the varnish on Stradivari violins revealed», https://phys.org/news/2009-12-secret-composition-varnish-stradivari..., with the original study published in Angewandte Chemie, International Edition, Volume 49, Issue 1, pages 197–201, January 4, 2010, http://onlinelibrary.wiley.com/doi/10.1002/anie.200905131/abstract, where we have to pay to read the whole research.
These old instruments were played for centuries, maybe that's one reason they sound extraordinarily well.
Very cool!
I think what Taffy is demonstrating is micro thin coats - several of them, sanded in between. It's gotta be fairly thin 'cause I can still see shadows from the wood grain (beautiful stuff, btw). Even the nitrocellulose they use on "fancy" guitars is basically a form of plastic.
I'm guessing most finishes alter the sound of the instrument in some way. I've shot spray poly on 4 of the CB Ukes I've built and they still sound fantastic. 3 coats each, as I recall. Super thin and sanded between applications. Did it mostly to protect the fancy paper and stickers.
Many many Highly regarded luthiers use shellac "French Polish" on their very very expensive guitars.
There is a product called Hard Shellac, but it is made especially to be hard.
I use the wax to get the sheen I like.
Cheers Taff
Taff
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