Finishing Sand Paper
Take a look at your guitar. You see how the finish is perfectly smooth and shiny? Well, at least it was when the guitar was brand new. Guitar finish is not inherently that smooth or shiny. After the finish is sprayed on the guitar, it gets wet sanded with a few different types of sand paper. Each piece of sand paper is important if you want to get that smooth shine on your guitars.
There are many different types grits of sand paper. Sand paper is measured in grits per square inch. Each sand grit is a small spec of sand material that is stuck on the sand paper. For instance, 120-grit sand paper means on every square inch of sand paper there is 120 grits of sand material. Fewer grits per square creates a courser piece of sand paper. Common grit sizes of sand paper include 80, 120, 240, 320, 600, 800, 1000, and 1200. 80-grit sand paper is much courser than 320 grit sand paper.
During the guitar finishing process you will use all of these various pieces of sand paper at some point. Long before the lacquer is sprayed on your guitar, it will need to be finish sanded. Finish sanding a guitar is simply sanding the imperfections out of the wood and getting it ready for finish. On an unfinished guitar body, you will start with either 80 or 120-grit sand paper. This just depends on how rough the wood is. After the entire body is smooth, step up to the next highest sand paper: either 240 or 320-grit. Once the body is brought up to about 320-grit sand paper, it is ready to be sprayed with finish. Spray the guitar with about five coats of finish, one being a sealer coat. Then you will need to wet sand it with 800-grit and up sand paper. Then repeat this process. After about 10 to 15 coats, your guitar should have a nice thick finish on it. Wet sand it with 1,200-grit sand paper and buff it out. Your finish will look like a mirror!
Sand paper is a guitar builder or repairman's best friend next to saws and routers. Every step of building and some steps of guitar repair require sand paper. You can't really have a functional guitar repair bench with it. I suggest getting at least a few sheets of every size of sand paper. Once you do some repairs and build some guitars, you will know what grit sand paper you favor. Then you can stock up on it. Sand paper is an essential tool that you have to have. There's no way around it. If you would like more information about how to finishing guitars, please see my how to finish a guitar article.