The whole thing began when I made my first instrument on the kitchen table.
Jose Romanillos, Luthier
Most how-to-make-your-own-guitar books recommend that you use lacquer to finish your guitar. A good choice, lacquer is a durable and wonderful finish, but even as John Bogdanovich points out in his book, Classical Guitar Making, applying lacquer is not easy, not to mention you should invest in a good quality HVLP spray gun outfitter and purchase the proper Personal Protection Equipment to protect you from the lacquer's toxicity to spray lacquer. (Okay, woodworking geeks, you can jump in at any time to tell me how wonderful spraying lacquer is!) .
You can buy aerosol cans of lacquer from Stew-Mac and other luthier supply houses to finish your guitar. I hear good things about going that route, it just reminds me too much of when I painted my '59 Chevy pickup with cans of spray paint my sophomore year of college (1982).
Cumpiano and Natelson recommend brushing lacquer, which I think is another good option, but don't forget that you'll spend a lot time sanding out the ridges in the finish left there by the brush. If you are good at painting you won't have a problem with a brush, so brush away. That said you could also use Pratt&Lambert's 38 Clear Alkyd Varnish and brush it on the way that Manuel Velazquez and his son Alfredo do on their famous guitars.
Oh, and don't let anyone tell you that french polish takes too long to apply, is too hard to do and is beyond the scope of any fledgling luthier, that's just BS. Buy Ron Fernandez's video French Polishing for Guitarmakers, follow his instructions and you will be impressed.
What I am getting at is that there is no easy way to apply a finish to a guitar, I know that those books make it look easy, but it isn't until you've done several guitars. Accept that fact and just do it. Don't fall like I did for the articles in Fine Woodworking magazine about the latest and greatest easiest-ever-varnish-to-apply. They don't work well on a guitar. And see my previous post about using Behlen's Rockhard Table Top Varnish, it dries hard but turns as yellow as a dandelion in one year.
The following photos are of my guitar #3, I built it 10 years ago, that I stripped over the weekend. It's not a fun thing to do and I even used a "green" varnish remover. After I built it I finished it with the aforementioned Behlen product and an alkyd varnish concoction from the pages of Fine Woodworking, the results were less than pleasing. I will say it again, I wish that I had learned how to french polish when I first started making guitars.
I am a huge fan of french polish and I urge anyone who wants to make a guitar to use that technique. I say pick one tried and true finishing technique and use it, don't experiment with other finishes until you get the hang of the one that you are using.
P.S. I'm not trying to scare anyone off from making a guitar, anyone with or without woodworking chops can do it. Go ahead, start today!
Here's a YouTube of Mark Anthony Mcgrath. Enjoy