Wednesday, November 28, 2018

The Best Ingredients for a Fine Wood Finish

When I first started down the road of lutherie back in 1992, I had several spectacular finish failures. Some where I had read that you could use tung oil on a mountain dulcimer, and I found out that you can, but it killed the sound of that very first dulcimer. I hung it up on the wall.

All the wood working books and catalogs of the era seemed to state that wipe-on finishes were the best, or that it was better to buy some fancy brush-on finish that self-leveled was best to use on guitars and dulcimers. I bought brush-on varnish from a big name wood finish supplier and smeared it all over a "custom" dulcimer I made for a friend. I level sanded with wet/dry sandpaper and mineral spirits, but no matter what I did, the white dust from sanding adhered itself to every little nook and corner of the dulcimer. No matter how hard I tried I could not get rid of the white dust specks. My friend like the instrument anyway and was very happy with it.

After making several dulcimers I took the plunge into making my dream instrument - the classical guitar. The books I used to help me to make the first guitars were quite wonderful in showing how to put all those pieces of wood together, but every book steered me away attempting to learn how to French polish. I got the feeling that "French polish" and "shellac" were dirty, nasty words that weren't suppose to be uttered in the presence of a maker of fine classical guitars.

So, I started to cast about for a finish that would work well for classical guitars. I don't remember what I used on my very first guitar, it was probably some "wipe-on-with-a paper-towel" concoction made by mixing several different varnishes. I got that recipe from an article in a well known wood working magazine. It wasn't a glossy varnish, sort of semi-gloss and rather disappointing, though I must admit that that guitar is still being played today by a rather good guitarist and I haven't heard him say anything about the finish.

Then I read that the best guitar finish was a bar top varnish that was impervious to everything including battery acid. I bought a quart of the stuff, painted it on a guitar and let it dry. Three days later I noticed a slight bubble in the finish and when I picked at it two thirds of the finish on the guitar's top peeled off in one smooth motion! When I finally got the varnish to adhere to the wood's surface, I discovered that within one month's time the varnish turned yellow, yellow as a dandelion's flower. I ended up stripping three different guitars. Those I applied over-the-counter shellac, level sanded it all and called it good.

There were several interesting articles on French polish that I read early in 2000, but every time I tried to follow the instructions all I had was a surface that had some shellac on it. It wasn't until I picked up Ron Fernandez's video on French polishing that I got an inkling about this wonderful skill. By the way, the video is still available, please contact Mr. Fernandez  or go to Luthiers Mercantile.

Since then, I have whole heartedly given myself over to French polish. It is an adventure that never stops, because just when I think I have finally figured it out, something little technical aspect pops its head up and tells me I am doing it incorrectly. Then I have to figure out how to fix the issue and most of the time I can find a solution in one of the very old books written on French polish. French polish is an old skill and craft, somebody figured it out long before I got here.

The best ingredients for a fine wood working finish are found in your patience and willingness to take the time to make a great finish. Somewhere, on some forum I found, a woman who runs a finishing shop somewhere here in the United States, weighed in on a thread about shooting nitrocellulose lacquer.  I didn't write down her exact quote, but she did say "there is no such thing as a quick and easy high class wood finish. You have to take your time."

My goal is to make the best guitars I can and part of that means putting a world class finish on these beautiful instruments. That entails several days of raising the grain and sanding;  then pore filling with pumice and shellac and waiting for week for that to harden and do it all over again until I have a glassy smooth surface; then session after session of applying a two pound cut of button lac shellac until you can literally "see" into the wood. When that happens, every second and ounce elbow grease is worth it.

1 comment:

  1. Wonderful post, Wilson.

    And that woman is so right and you can apply that to pretty much every aspect of woodworking! Take your time. Do it right. You'll always be happier with the end results.

    ReplyDelete

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