Thursday, March 26, 2009

Acoustic Guitar Magazine French Polish Article

Used most often to finish luthier-made classical and flamenco guitars, French polish is surrounded by more myths and opinions than virtually any other aspect of guitar making. French polish has been a common furniture finish since before the Victorian era and was probably first used on instruments as a faster-drying alternative to the very slow-drying varnishes used on violins. French polish shines with a delicious, organic, old-world elegance, and bonds perfectly to wood. Because it is extremely thin, it allows for the best possible tone, and it can be easily repaired and reconditioned at any time. Let's take a look at what French polish is, as well as its application and care.

French polish is simply a shellac finish that is applied by hand—rubbed on with a small cloth pad. Shellac itself is a resin that comes from a secretion of the South Asian lac insect, which feeds on the bark of trees. Color variations in the shellac come from the variety of trees the insects feed on. The secretions are crystallized into flakes, like thin peanut brittle, which are dissolved in alcohol to make liquid shellac. It is mixed in small portions because liquid shellac has a relatively short shelf life (about six months). Most luthiers come up with their own mixing system and thin it according to need and the way that a particular batch of shellac behaves.

The main reason luthiers use the French-polish technique is to cover and protect the instrument using the least possible amount of finish. To meet this goal, the shellac is rubbed on by hand one ultrathin layer at a time, using a pad made of a piece of linen wrapped around a wad of cotton or wool. Although it generally requires the application of several hundred layers, French polish is still thinner than most other finishing options.


The process begins with the application of a thin wash coat of shellac to the whole instrument (using a pad). Then the chosen filler is applied. Porous woods, such as rosewood, need to have their pores filled, which is commonly done with commercial paste fillers, epoxy, or the old-world solution of pumice. Pumice may seem an unlikely filler since it is a powdered stone that looks totally white, but when suspended in shellac it becomes translucent and absorbs the color of the wood as it's rubbed into the pores. Pumice is like lightweight powdered glass and has a hardening effect on the surface of the wood. This effect is partly responsible for the clarity of sound a French polish gives to an instrument—pumice isn't just pore filler, but becomes part of the surface of the wood, which affects the instrument's resonance. Pumice or other fillers are never used on soundboard woods like spruce and cedar, and other less-porous body woods such as maple or cypress give a beautiful finished surface without the use of fillers.


Once the pores are filled, liquid shellac is applied with the pad in small circular or figure-eight motions; in this way, the luthier continuously adds, spreads, and smooths a tiny amount of shellac resin dissolved in the alcohol. Sometimes, but not always, mineral, linseed, or walnut oil is used to lubricate the pad and keep it from sticking and marking the finish. As the alcohol evaporates, the resins are left behind. This process continues until hundreds, or even thousands, of microscopically thin coats are in place and the desired finish achieved. The work is done in sessions of about a half hour, maybe three sessions in a day, then repeated in a day or two, perhaps taking three days total. It is important to learn when to work and when to rest, to find the optimum balance between building coats and drying. It's hypnotic work and, with the smell of the alcohol, quite pleasant. Once cured, it is possible to sand and buff French polish as you would lacquer, but it must be done very carefully, because shellac is much softer than lacquer.

There are many debates among luthiers about which oil, alcohol, shellac, filler, or kind of pad to use—it's almost scary how strong opinions can be. There is also a wide range of thought on how long it takes to do the job: a day, five days, a month, a year. In my shop, the finish is applied in about three days and cured for two to four weeks. (The longer the cure the better, but we're anxious to play the instrument, not just look at it.) In a pinch, I've applied a complete French polish finish in one day, let it dry another day, strung the guitar up, and hopped on a plane without a problem. I don't recommend it, but it can be done.


French polish does have some liabilities. It scratches easily, especially on soft woods, such as spruce or cedar. It is also susceptible to heat, which can soften it. A guitar left in a car above 95 degrees Fahrenheit will probably receive an imprint from the case or, more disturbing, may stick to the case lining. Moisture can cloud the finish, and the body chemistry of some players can cause problems, crazing the contact surface over time. For someone who has experience using French polish, repairing the finish is an easy job, but using a method appropriate for other finishes can be a disaster. A poorly informed repair tech might use some finish other than shellac to do touch-up, might sand too aggressively, or might not have the skill with the pad and the shellac to blend, fill, and smooth the finish. At the same time, someone with the right skills and experience can often renew a French polish in minutes.

To take care of French polish, lightly rub with a soft cloth to clean it, and avoid the common enemies of heat, moisture, and fingernails. Also remember that small flaws and damage can be attended to any time, so don't be too worried when something does happen—it can be dealt with later.


As guitar makers continue to look beyond their own niche for ideas, French polish is increasingly showing up in place of other production finishes. Steel-string luthiers such as Michael Bashkin are offering French polish as a finishing choice, and even the Santa Cruz Guitar Co. is offering a French-polished soundboard option on its Tony Rice model. It is fairly common to use shellac on the soundboard only, but using it on the entire guitar is the norm for classical guitar makers.

Me, I just love the stuff. I love how it looks, how it feels, how it smells, how it sounds. My company has used it on hundreds, maybe thousands, of guitars, and I don't even own a spray gun anymore. I expect that in the future this small renaissance will grow, with more luthiers and players becoming comfortable with the small miracle of French polish.

Kenny Hill

This article appeared in ACOUSTIC GUITAR magazine January 2009 issue 193

Thursday, March 12, 2009

Designing/Building a New Signature Model pdf #4

We've tried to find the best way of consolidating all this information. We've laid it out on the web with photos and all and also found acrobat might be a nice way to do it. Please check this out and let us know what you think.

to see this article compiled with photos click here or to download a 10mb pdf file Building.pdf

Thursday, March 5, 2009

Designing/Building a New Signature Model #3

Kenny Hill
Now this first lattice braced double top guitar has been completed, and it really is quite interesting. I've changed a lot of things all at once, expecting a sort of monster truck muscular guitar, and to some extent that's what I got, but not completely.

This was a very opportune debut, because on the same day I was able to string up a standard Signature, with the same woods and all of the more familiar design elements, so I got a perfect side by side comparison. It was an ideal situation. The new "standard" Signature was a really good cedar/Indian one, as good as it gets. It's an exciting guitar to play, and I still like it better than the newer experiment, but it's no slam dunk.

The sound of the lattice is interesting. It's explosive, quite immediate. At first it seemed limited in its color range, but after a few days of playing it began to really open up. The bass is spectacular, and the highs are filling in quite nicely. I showed the guitar to Ricardo Cobo, and it reminded us both of the Humphrey he's been playing for several years. That's not necessarily what I was going for, but it's a curious observation.

Comparing it to my "standard" Signature, I'd have to say that the original recipe still is more sensual, a complex and wet sound that's pretty darn wonderful, while the lattice top is a more masculine and muscular sound. A lot of these subtleties start to blend as distance increases, so it raises the question of which is better for big hall concert playing and which is better for personal and small room playing. Actually, either one will do brilliantly, but I am always aware of the variety of people and players that I am building guitars for, and that everybody doesn't need or want the same thing. It's an interesting mix.

Scott Tennant also played both of the two new guitars, and he actually selected the cedar "standard" Signature for himself, but he sounded real good on the lattice too. Evan Hirshelman spent a bunch of time playing the lattice, and seemed to really bond with it, lusting after the bigger basses. Evan is a great player, his compositions are amazing. He's playing a spruce Signature now, and we'll have to see what happens later.

So over the last week I've made another of the bigger Signatures, (I don't really know what to call it yet - monster truck doesn't quite cut it), but this time with my regular fan bracing instead of lattice. This will give me the chance for another side by side comparison. Tomorrow I'm going to China for ten days, and when I get back the varnish should be about done, so I'll be able to string the new guitar up and learn some more by playing it. I'm really anxious to hear it.

Naturally I'm still puzzling over what to do with all of this. I have imagined in my head a melding of lattice and fan bracing, hoping once again to lift the best qualities from both worlds. I don't know if this push implies a psychological inability to commit, or just my gluttonous and insatiable nature, wanting it all, in every way. To realize this bracing fantasy will require me to make a lot more sawdust, and probably have some strange results along the way. But regardless of the Freudian implications, I won't know if I don't try. I expect I won't be able to get to this next phase until mid April, but If I get to steal some time some weekend or some sleepless night, I can't wait to try it.

to see this article compiled with photos click here or to download a 10mb pdf file Building.pdf

Tuesday, March 3, 2009

Designing/Building a New Signature Model #2

I wrote the first installment of this blog while I was working on my newer model of Signature guitar. At the time I was also preparing for the NAMM show, and managed to get the guitar assembled just before the show, and with the help of my wonderful staff the guitar was French polished while I was gone. The timing was good for the guitar. Then when I got back from the show we had this ridiculous guitar theft by fraud, which had the understandable effect of breaking my stride on this little blog series, but I am happy to get back to it now. The ramifications of the theft are still with us, but "what-ever", I'm much more interested in getting back to the real work of guitar.

Larry has shot a lot of working pictures and we've culled out just a few. This is by no means the complete process, since a lot of the work was done early or late in the day, when there was no camera around. Overall this process is going to take a few guitars to work out, so perhaps with more pictures over time we'll get a more complete sequence.

For guitar makers this will be mostly old hat, and for non-guitars makers it might be undecipherable or boring, but for me it's fun to think about. As I've said, I have to work in the breaks between other responsibilities, but that's the way it goes. I'm at home with this rhythm and I'm grateful for the opportunities.Kenny Hill Lattice Classical Guitar

What I'm trying to reflect here is more about the development process, both the thought processes and the blind alleys. I'm not much of a planner, but rather I let the material and the results pull me forward. Then, afterward, I try to come up with an explanation. I don't know if this is right or wrong, but It's beginning to look like it's not going to change any time soon.

The lattice braced double top soundboard was already made before we started shooting pictures, so I'll have to show that process some other time. I'm still thinking about how to make the lattice work better, make a more complete and delicious sound. I have some ideas, but it's going to take a few attempts to work it out.

to see this article compiled with photos click here or to download a 10mb pdf file Building.pdf