Sandpaper: A Brief Overview
The way I see it, there are four types of sandpaper in building musical instruments:
Now, depending on what type of finish you will have on your instrument, you may not need numbers 3 and 4.
I want to discuss each category of sandpaper: what grits are used, what techniques and tools are used, along with recommendations for brands and makes of each type of sandpaper.
1. Sandpaper for leveling and shaping wood
Here, I'm not too terribly picky with types of sandpaper. The typical ranges I use are 50, 80 and 120. Again, this is mainly just used to shape out imperfections and leveling high spots, etc.
I tend to avoid 50 grit unless I absolutely have to use it, because it is so aggressive, and the scratches left are pretty deep.
For me, just about any brand will do, although I like how Norton has some of their grits color-coded, so its easier to tell them apart.
2. Sandpaper for smoothing wood
This is were I start to get a little more particular about the kind of sandpaper I use. Basically, all you are doing is getting rid of the scratches made with the paper in step #1, and preparing the wood for applying a finish.
The grits I usually use for this are: 120, 180, 220, and sometimes 320.
The problem with listing grits is this: these are just the average particle size ratings of the sandpaper. It says nothing about how sharp these particles are, (IE - how fast they cut), nor how tight of tolerances the particle size is under.
In other words, a finer grit sandpaper can still leave big scratches if the paper is of low quality because the grit is simply the average of all the particles - it may have really big and really small bits mixed in. Also, the quality and sharpness of the abrasives can differ, dramatically changing how fast the sandpaper actually cuts. For instance, I've noticed that a Norton 3X sandpaper rated at 320 grit can usually cut faster than a cheaper sheet of 220 grit.
Here's an overview of the brands I've tried:
3M regular - Okay for the lower grits, but I really don't like how slow it cuts and how quickly it clogs in the higher grits, and in demanding situations.
3M Sandblaster - In my experience, not a whole lot better than the plain old 3M sandpaper. I've found that it does not resist clogging as well as it has claimed to. If you're going to get something cheap, buy an off-brand, but if you want something better, this isn't the stuff.
Norton 3X - One of my favorites. This sandpaper only costs slightly more than the 3M, but really does last longer. (Probably not three times longer like the name implies, but it is markedly better) It also cuts faster than standard sandpaper; highly recommended.
3M Gold - I've not yet tried these papers, but plan to very soon. The main drawback on this sandpaper is the price, and lack of local availability. Beyond that, they are supposed to be some of the longest lasting and fastest cutting papers available.
3. Sandpaper for leveling a finishThis is where I get extremely selective about what sandpaper I use. A finish is very thin, and I can't afford to use a low quality paper that will get clogged quickly and drag gobs of shellac across the (previously) nice finish. It is also quite inefficient to be changing out the paper all the time. So, referencing the list of brands above, I typically only use the Norton 3X to level a finish, though I am eager to try the 3M Gold product.
The grits I typically use for leveling are: 320, 400, and possibly 800. I say possibly 800 because the Norton is available only up to 400 grit, but the 3M Gold comes in grits up to 800. A coarse grit of MicroMesh could also be used (1500 grit) but I'd rather use something that is not so expensive. (More on this below.)
4. Sandpaper for smoothing a finish
This is a category where you really don't have to worry about using cheap sandpapers - they don't exist in this high of grits! Basically, once the finish is leveled, all you have to do is take out these small scratches with progressively finer abrasives until the desired gloss is achieved. (A task that is much easier said than done!)
I'll be honest in this section: I hate wet sanding. I will obviously have a strong bias against it, so keep that in mind when reading this section.
My absolute favorite material for smoothing a finish is Abralon. If you've never heard of this stuff before, I highly recommend it. It's quite a unique material, and would take a considerable sidetrack to explain it all in detail, so if interested, please see my write-up on this on my blog. Abralon is available up to 4000 grit, and can be used dry. I use 1000, 2000 and 4000 grits. This will get you to a semi-gloss finish. If a gloss finish is desired, you have to use buffing compounds the last bit of the way to finish off.
A commonly used technique in the furniture industry is wet sanding with standard silicon carbide sandpaper. (Usually colored black.) Once the scratches are small enough, a combination of rubbing compounds and polishes are used to bring the piece of to the desired gloss. (Traditionally pumice and rottenstone.) This is perhaps the least expensive, and most time consuming way to do it, though it does have sort of an "old world charm" to it. (A polite way of saying it is a mindless chore that even an orangutan wouldn't enjoy.)
Another option is MicroMesh. This is a specialized form of sandpaper that starts at 1500 grit and goes all the way up to 12,000 grit. (Yes, you read right: twelve thousand.) This will take you from the leveling stage all the way up to high gloss. The only downsides are these: there are a total of 9 different grits, which make for a lot of elbow grease. The higher grits must also be used with a lubricant (IE - wet sanding) - a sloppy, unpleasant experience which I detest. And lastly, MicroMesh is incredibly expensive. On the upside, the sheets do last a long time, but for the price, I'd rather have Abralon.
Or, you could simply use #0000 steel wool, and leave the instrument at a satin finish. (I know, steel wool isn't technically sandpaper, but it serves the same purpose.) If you've leveled the finish beforehand, steel wool can leave a pleasing, down-to-earth appearance.
Copyright © 2010 Eric Meier