Acoustic Guitar Construction

From an interview with David Antony Reid:

DAR: Finishes for me is a really big one. You either want an instrument to be an ornament; or you want it to be a working tool. I do both finishes. Gloss lacquer, polished to a pristine shine. Or, I have my RealWood finish, which is a thinly applied matt nitro cellulose without any grain fillers. There’s too much to explain here as to why I do this, but I have a big write up on the “Projects” page of my website, under the heading: FAQ.

In short, to achieve a perfect, flat sheen on a guitar, you need to fill the grain and build up enough layers of lacquer to ride over any fine discrepancies in the wood. Now, that might seem like a very fine tolerance; but in the “fine” musical instrument sense, it’s huge! You only have to feel the difference in weight of an instrument after all of the gloss lacquer has been applied to realise the difference it’s going to make to the tone of the real wood. The violin family of instruments don’t suffer sacrilege in this way, so why the guitar? It’s mainly because most guitar players want an ornament. But just because it’s not shiny, it doesn’t mean you can’t appreciate the natural beauty of the RealWood!

A gloss lacquer does offer marginally more protection in the way of dinging the guitar etc; but for me, when it’s a working tool, I can live with that. So the majority of my customers who buy a Realwood finished guitar are working musicians who notice the difference this kind of finish makes to the tone. Or they’re just very careful in nature

Here's a pic. He gets big money for these, in spite of the matte finish.

A bit more interview. I'm only posting this for informational purposes, but please comment if you want.

"To understand why I decided to use this finishing method, here are the details, so read on if you are interested, or can be bothered?!

Whilst studying instrument making at university, I conducted lengthy laboratory experiments with many different types and amounts of finish, on many different timbers. The results, achieved using a 100% humidity cabinet, a 12% humidity cabinet, typical construction environment conditions – usually 45-55% humidity – and then equations to calculate moisture content, were, quite frankly, seriously surprising! It would seem that a heavy gloss lacquer helping greatly to protect your instrument from the environment is a great misperception. Quite simply, wood is hygroscopic; and even when completely soaked in several coats of Acid Catalyst lacquer – the finish that showed the highest level of protection – the wood still absorbs, or loses, the moisture from, or to, its environment.

Further to that, it is very surprising how little an amount of finish is actually required to protect the outside of the instrument from dirt and grime penetrating the timber. Therefore I concluded, that all that heavy gloss finishes were doing, was restricting the instruments movement. The violin family of instruments do not suffer sacrilege in this way, so why the guitar?

Well Dave this is very interesting info for sure. I had a Honer Contessa dred that I bought in 1971 that was mahogany and had a satin finish. In fact I don't think the pores were filled. I really liked it because finger prints didn't show on it. I do personally like the satin finishes but I would want to make it smooth. As far as the amount of finish, personally I doubt that the normal average person is going to hear much difference between the two type of finishes. In Bogdanovich's book, he claims that a guitar without finish does not sound as good as one with a finish on it, so that is pretty interesting too.

My experience with reasonably thin lacquer finishes has been they inhibit getting max volume for the first months and even a couple of years - as they continue the off gassing and hardening process. Eventually, it becomes easier and easier to get lots of volume with minimal force.

But they are gorgeous if done with a modicum of care, and the whetting aspect emphasizes color and grain like crazy, without the need for stain.

If one were going with the minimum amount of finish necessary to protect the wood (versus make it look like a new car), why not use shellac? It is not toxic or explosive and reaches max hardness quickly. It is not as tough as lacquer when heavily applied, but we are not talking "heavy" here. And it is easier to repair.

In just three or four posts there is a 180 contradiction made by two creditable guitar makers -- as usual I recommend that design "absolutes" should be avoided in guitar making conversations. Based on my observations of the wide variety finishes used by the so called masters around the world, my personal "as usual" recommendation is --- as long as you don't glop huge amounts of finish on the sound board, once its dry our human ears will not care what was used to protect the guitar.

As far as the appearance, I've become partial to the satin finish -- for marketing perception I'll go with a French polished sound board.