I am building a hall table and using veneers that I cut from a stunning piece of curly Koa. The drawer fronts are Koa veneer and the table top is book matched Koa veneers. Although I have been wood working for quite awhile, I know next to diddly about finishing. I have always used 3 or 4 coats of Danish Oil, let it cure and then a couple of layers of wax. This has been a surprising durable finish on several bed frames I’ve built. With this hall table, I want to give the top some extra protection, so starting with the drawer fronts, I used 3 coats of Watco Danish Oil and then top coated with Watco Wipe-On Poly. This has been disastrous. Perhaps I didn’t wait long enough for the oil to cure. The finish is tacky and dull. Now, I’m trying to figure out what next. I think I’ll try to remove the Poly with denatured alcohol and then perhaps settle for my old tried and true, even though I’d like to put something more durable on the table top. My wife wants a satin finish, so high gloss options are out. Any suggestions?
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Replies
Sand off all the sticky and apply spar varnish and linseed oil 50/50 with some mineral spirits. Apply wipe on and off. Do several coats. You will be able to repair in the future and have a durable finish.
To really bring out the figure in Koa and accentuate the colors, I highly recommend using Danish oil or a 3 part mix of oil varnish, turpentine, and linseed oil.
Then once that's dry, use super blonde shellac. Shellac is durable, and it refracts the light to really bring the wood's true nature to the surface. You won't go wrong with this finish.Inspiring Your Passionate Pursuit of the Craft
P.S. Stay away from poly of any kind. It doesn't deserve to be used on wood as fine as Curly Koa.
Edited 11/17/2009 5:25 pm by ak
Does this produce a gloss finish? I will bag the poly. It has certainly been a disappointment on the Koa, although it did fine for me on Mahogany.
Shellac can produce whatever look you want. It can go flat all the way to mirror finish. It's up to you. I know you said it shouldn't be a gloss finish, and I agree. A "satin" look will be best.Inspiring Your Passionate Pursuit of the Craft
DO NOT TRY TO SAND OFF THE FINISH THAT ISN'T CURING. This wouldn't be a very good idea even on solid wood, but with veneer disaster could be lurking right around the corner. Uncured finish will clog the paper almost instantly anyway.
Denatured alcohol will have no effect on removing the varnish. It is only a solvent for shellac, (and to some degree a thinner, but only a solvent for very old lacquer.)
I would first try mineral spirits, or perhaps lacquer thinner to try to remove the uncured varnish. If that doesn't work sufficiently, then you should use a methylene chloride based stripper to remove the cured oil-based finish. Be sure to use personal protection and adequate ventilation. The MC stripper is most effective, but also hazardous if used carelessly.
Curing time of the Watco Danish oil depends greatly on temperature, and also whether you followed the directions to vigorously wipe off any excess after allowing it to penetrate for a short period. Left on the surface to try to provide a film it can leave a soft, gummy material. If you are overcoating with a varnish, one coat of oil, or oil/varnish mix is enough.
A good choice for a varnish top coat would be Waterlox Satin, thinned just a bit to wipe-on consistency. Differences between using this directly, or over an oil or oil/varnish initial coat would be extremely subtle, to say the least. The number of coats will determine how protective it is, and at the same time, how much visible it is as a film.
Strip off the gunky stuff that's on it now, then let the wood sit for a few days at least. This assures that all of the old finish, and all of the old solvents, and all of the stripper are gone (or at least inert).
You can use an oil if you want, but if you do, be sure to let it fully cure. Curing is not just drying. Drying for many oils is one day. Curing is longer -- think in terms of a week or more.
Then use dewaxed super blond shellac. Don't worry about brush marks or unevenness much -- just build up numerous coats (8 or 9?).
Then start to rub it out. Start with 220 or 320 grit wet/dry sandpaper and water. Block-sand the piece till the sandpaper scuffmarks are even. Then go to the next higher grit, and do the same. Note that it doesn't take much work at each grit, but each is vitally imnportant.
Work your way up from 220 to 2000 grit (if its not available at your woodworking supplier, go to the auto parts stores.) At 2000 grit, you should have a very good looking "semigloss" finish.
Depending on the size of the workpiece, all of this will take a couple of hours.
If you want the highest of gloss, you need to use a rubbing coumound. This is a liquid-form abrasive that is also found at the auto parts store. Dribble some on, and rub with a soft cloth.
Bingo -- high gloss. The kind of high gloss that show cars have.
Note that the biggest potential problem is that you won't put enough shellac on before you start sanding. If that's the case, you'll sand through to the wood when rubbing it out. (And you'll need to start over.)
(And this can also be done with brushing lacquer, and perhaps with some varnishes.)
I won't be laughing at the lies when I'm gone,
And I can't question how or when or why when I'm gone;
I can't live proud enough to die when I'm gone,
So I guess I'll have to do it while I'm here. (Phil Ochs)
Yesmam,
Who wouda thunk that an auto parts store would be a woodworkers BEST friend.
I have done pumice and rottenstone with mineral oil, ONLY to discover that auto body/finisher chemists have perfected the secret to a short learning curve. Good advice.
Find your nearest supplier to auto body shops and ASK for advice. Tell them your desire and buy their advice. Make sure the supplier is one who most auto body folks buy from and is a true commercial supplier.
I have no advice about the finish here, except this -
NEVER 'test' a new finishing schedule on a finished piece of furniture. Make all your mistakes on scraps leftover from the same wood you're using. Go through the entire schedule, tape off a few separate areas so you can try some variations and then pick the best one. It takes time, but so does scraping off a failed finish.
Good luck!
finishing Koa
I was wondering about the process of using a pre-catylized laquer over a catalyzed vinyl sealer, over an oil like watco. This is for a high end Koa veneered dining table. Any help would be appreciated. [email protected]
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