On Acoustic Instruments the kind of finished used is extremely important. The perfect finish should be low in mass, have a low dampening effect and be durable enough to last.

So why are these things important? The latter is self-explanatory, we want the instrument to stay looking beautiful. The other two (mass & dampening) effects how the soundbox moves and the more the soundbox moves, the more sound it makes.

The sound of a guitar comes from a plucked string. The energy from that string is transmitted into the top and emitted from the soundhole. If the top is heavier or is restricted in someway, it is going to take more energy to move that top by the same amount, rather than if it was lighter and less restricted. Both of these attributes restrict the soundbox from moving effeciently and the sound it emitts. It's a very simple equation:

MORE MOVEMENT = MORE SOUND

I think at this stage I've tried or tested majority of lacquers on the market. At the moment I offer two types of finish one for a satin look and the other for a gloss finish.

Satin Oil Finish:

The satin finish is a mix of natural oils and hardners, which puts a real emphasis on the grain of the wood and the woods natural characteristics, which is warm and rich looking.

This finish can be applied very thin, using similar techniques to french polishing(but not as labour intensive) and is extremely low dampening. It is far more durable than french polishing and isn't effected by moisture and sweat like french polish is. Even though this finish isn't as hard as some of the other finishes on the market, it is very easy to repair and touch up. I love this finish on a guitar. It has all the attribute that I look for in a finish. 1) Durable. 2) Extremely low damping. 3) Easy to apply and repair. 3) No highly toxic solvents.    

Gloss Finish:

For those of you that prefer the high gloss finish, I use a urethane mixed lacquer that has been specially formulated for instruments that can be applied thinly. It is durable and has a  low dampening effect on the instrument and is more friendly to the environment than a lot of other finishes. This finish gives a look that majority of use would be more akin to seeing from factory finished guitar. Its gives you the flat glass like high gloss look.

There are a lot of finishes that other manufacturers use. Here is a little run through them and why I don't use them.

Polyester:

This finish is the go-to finish of many factories across the world. It's mainly used because how quick it can be applied and its short curing time before it can be polished. This makes it a very suitable finish for the high production enviroment. It is also very durable and can take a lot more punishment than most other finishes. But on the down side, Polyester has a very high soild content (mass), which makes it difficult to be applied thinly. This is good for the manfacturers, as they have to put fewer coats on to achieve a durable finish, but bad for the sound of the guitar. All this extra mass inhibits the movement of the guitar and because "Less movement = less sound" I never use this on any of my instruments. Another negitive is that it requires specialist equipement and contains some nasty chemicals which are bad for your health and for the environment.

Another down side to polyester finishes is that it is very difficult to repair. 1) Because its very hard and durable, leaves it brittle. So when/if it receives an impact the finish can actually crack. 2) It doen't "burn in" to itself. What this means is that it doesn't melt into itself. this can leave witness line when trying to repair. 

Shellac (French Polish):

Shellac is probably the least dampening of all the finishes. It's easy enough to apply (even though very labour intensive) and requires no specialist equipment. The downside to shellac is that its not very durable. It marks very easliy from nails or picks and can become cloudy from sweat or moisture. It's also very labour intenstive and takes many hours to apply. I have found that the majority of musician require a more durable finish than shellac and I dont normally use it unless requested. I find that my satin oil finish a great substitute for shellac and doesn't require the care that shellac does.

Nitrocellulose:

Most Musicians have probably heard of nitrocellose. It has low dampening effect, can be applied thinly and has been the go to finish for many high end builders for decades and for good reasons. The cons of Nitro is that it has a long cure time and is full of nasty solvents. It is also getting increasing harder to source, with environmental agencies trying to push industry into using more environmentally friendly options. Another negative is it needs specialist spray booths and safety equipement to spray it safely. These days I rarely use Nitro due to its environmental effects, but more importantly for my own health..