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.

Tuesday, November 27, 2018

Building an Eight String "Brahms" Classical Guitar, Part One

Among God's creatures two, the dog and the guitar, have taken all the sizes and all the shapes, in order not to be separated from the man.

Andres Segovia, classical guitarist

Early this year, a young composer/guitarist asked me if I would make him an eight string guitar, the so-called "Brahms", or cello, guitar. It has an extra treble string and bass string, this extends the musical range of the classical guitar in a tremendous way. This guitar was developed in 1994 by the luthier David Rubio for the guitarist Paul Galbraith, and if you wish to read more about how this guitar came into existence, please go to Wikipedia or Paul Galbraith's website to learn more.

There are no plans, that I know of, for this guitar, I knew that the first Brahms guitar had a bass string length of 660mm and the treble string length of 630mm, and today most makers use 650/615mm string lengths. I chose a 650/620mm string combination and pulled out a roll of brown paper to start my layout.

My biggest concern was to place the bridge in the most responsive place of the guitar's lower bout. Historically, a maker usually puts the bridge just ahead, more towards the sound hole, of the center of the guitar's lower bout. I drew plans using outlines guitars made by Jose Ramirez III, Hernandez y Aguado and Antonio de Torres, but it seemed to me that there wasn't enough room in the lower bouts to make a more responsive guitar. An outline used by Santo Hernandez spoke best to my visual senses at the time and I chose to use that one.

(This matter of the guitar's outline is pure speculation, I am sure that any outline would have worked. In retrospect, when I make the next Brahms guitar, I will probably use the Ramirez outline simply because the upper bout is wider than the others and will visually balance better with the wider neck and head stock.)

Layout of the fret placement was made very easy with the help of R.M. Mottola's wonderful website. He has a wonderful multi string fret calculator which was invaluable to me in making this guitar, I need to send him an email thanking him for this wonderful service.

After drawing the plans, the next order of work was to make a mock up of the neck. On a standard classical guitar, you cut the neck blank straight across with a 15 degree bevel, but on the Brahms guitar I discover that along with a 15 degree bevel cut, there is also a 10 degree crosscut! (That is for a 650/620mm string length, the angle would be different for a 650/615mm length!)

I took a piece of lodgepole pine to make the mock up neck.

Here is the neck after I have cut a 15 degree bevel on a 10 degree crosscut. At this point on a standard classical neck one can put the two pieces together in a scarf joint and see how good one's saw skill are, but...

with two different angles the pieces don't make a nice scarf joint.

The pieces are planed to make a nice joint...

and then the pieces come together well.

Once I made the mock up I made the neck for the guitar.

The guitar is nearing completion, I am in the middle of shaping the neck, there are three frets that need to be added and then I can start the finishing process.

Stay tuned for more on how I made this guitar!

Friday, November 23, 2018

The Beauty of a Simple Butt Joint

The strength of a butt joint is merely that of the glue employed...

Bernard Jones, The Complete Woodworker, 1980 edition

I made this guitar neck about five years ago, and for some reason, I never got around to building a guitar on it. It is made from a nice piece of Spanish cedar with a slice of East Indian rosewood on the headstock. Earlier this month, I decided to pair this neck with a redwood top and flamed black walnut back and sides, but there was one repair that needed to be done before putting the neck to use.

I accidentally left the rosewood veneer a little short, it was about an eighth of an inch shy of the where the headstock slope meets to horizontal surface of the neck. Usually, I run this veneer a little wild and trim it back after the fret board is glued on and I am ready to install the bone nut.

I was afraid that I wouldn't have any rosewood on hand to match the original, but I got lucky and found a scrap pieces that was a fairly close match.

The repair was pretty straight forward.

Some judicious sanding with a sanding block to make a straight joint and at a 90 degree angle to the face of the veneer...

shoot the edge of the scrap piece with a block plane...

apply some high tack fish glue and clamps.

Everything looks good! I carefully cut off the excess wood...

then gently planed and sanded!

I am very happy with the way this repair turned out, I am especially glad that I found a good matching piece of rosewood.

Ebony Classical Guitar Bindings, New Neck for a Lacote Style Guitar

  There is still one guitar in the shop for repair, with the other repairs out the door I have some extra time to catch up on other work, li...