Steve Kinnaird's Notes on Finishing Koa

Anyone who has seen Steve's guitars realizes that his finishes are second to none. Here are his notes on his Koa finish.

One of the most appealing aspects of lutherie is the opportunity to work with the world’s prettiest woods. Surely, Hawaiian Koa ranks high on the satisfied luthier’s list. There is great variety within this species. Colors range from pale gold’s to rich chocolate browns. The figure can be mild-mannered, or wildly curly. There truly is something for everyone. I haven't yet met a piece of Koa I didn't like, but I admit a real preference for the highly flamed pieces. And I like them well enough to take a few extra pains with the finishing process. Of course, the objective is to accentuate the curl-- and it’s not that difficult.
P.S. This treatment does wonders for curly maple as well!

 

 

Photo of finished guitar made of flamed Koa.
  1. Prep the Koa back & sides your normal method.
  2. Mask off any white purfling's & inlays you want to protect.
  3. Apply a thin coat of Danish Oil to the Koa. This is the step that really “pops” out the curl. As an added bonus the oil imparts a nice amber tone to the wood. Don’t flood the work, or the oil could soak clean through the wood-- and result in visible stains on the inside of the guitar. Just wipe on and wipe off. Let dry overnight. (I use J. E. Moser’s brand, “Natural” color, #859-973, available from Woodworker’s Supply. (1-800-645-9292)
  4. Adhesion between lacquer and the oiled surface could be a problem. So as a go-between I apply next a coat of Qualasole (from Behlen). It is a padding- type finish that will dry “over most any wood finish”. I've found their claim to be true. (It would probably dry on water--if it wasn't too humid out.) Now your lacquer has a suitable film to bind to. You can also find Qualasole at Woodworker’s Supply. They don't always list it in their catalogue, but they do carry it.
  5. Next I spray a coat of vinyl sealer over the Qualasole. Since I use Lawrence McFadden brand of gloss nitro cellulose lacquer, I also use their sealer. It's a fine product, available from LMI. (Luthiers Mercantile) Spray it straight without thinning.
  6. Fill the pores using whatever method you find least distasteful, and then on to the final coats. If you’re going to be using a water-based product, all bets are off. I'm pretty sure steps 3 & 4 will only work with solvent based products.
I'd be remiss if I didn't caution you that oil-soaked rags are a fire waiting to happen. If tossed aside, they can spontaneously combust. I never give them the chance. As soon as the oiling stage is finished, I take them out to the driveway where they are burned. Then you can sleep easy, and dream of your beautiful handiwork!