60 grit, 320 grit, 150 grit.... what's the deal with sanding your wood? Well, first you have to ask yourself "why should I sand?" The answer to that question is two fold. First, do you intend on "finishing" your work piece? Obviously you do intend on "finishing" your work piece, you have taken a living breathing tree and turned it into some kind of object like you would like to utilize for any number of uses. Why stop before it is done? Second, why you SHOULD finish your work piece.
Three reasons Durability, cleanliness, protection. Depending on what type of "finish" you choose, you will be taking a work piece that you spent time crafting, perfecting (maybe banging against a wall when it did not go smoothly), and literally finishing it, seeing it through to the end, so that your masterpiece will be around for years to come. We will get into the different types of finishes, and why it is so important to finish them in another thread.
So sanding is a stop on the road of finishing your projects. Splinters, burrs, unsightly rough edges, etc. Lets start with the basics. As a rule of thumb, always sand with the grain. That means whatever device you are using, dremel, sand paper, sanding block, sand sponge, you want to run your tool parallel with the grain on the wood. A little cross grain action is permissible in those tight to reach areas where you just cannot go with the grain, but if you can, do it!
Generally you want to start with a rougher grit of sandpaper. The lower the number, the rougher the sandpaper. I am pretty sure that if sandpaper has a grit of one it is actually a bomb. 60-80 grit is a pretty rough grit and you can usually use this grit to do the brunt of your shaping work while sanding. If you have made cuts, saws, holes whatever, chances are there is some chunks missing, or weird bumps sticking out. This is where you would use the low grit stuff to blast it away. Put some sweat equity into your project and rub the sandpaper across the space you want to remove until it is gone. Your sand paper will eventually get clogged and dull, and not feel rough. That is the time to replace the piece you are using and stop wasting your time.
So if low grit is rough, high grit must be less rough right? Bingo dingo, but how high do you go? 320 grit, 600, 3000? Yeah sure those are great if you are trying to make your wood so smooth they can use it on the outside of the space shuttle launches. BUTT (thats right) lets talk about finishing again really quickly. Are you going to apply any kind of finish after sanding? Let us just say that your answer is "yes." OK, now do you want your finishing product to bond with your wood surface? Probably a safe bet to assume "yes" again, we're on a roll here. Ok well if you sand your wood so smooth that the next olympic committee contacts you to use your work for their figure skating surface, you have gone too far. Most finishes will not be able to bond with your surface if you sand too smooth. OK cool we are making progress. So, 150? Yup! That is as smooth as you will ever need to go if you plan on "finishing" your project. 150 if the perfect grit to sand your project to prior to applying a finish. If you are not going to apply a finish, you rebel, than sand to 320. It will be butter smooth, but your wood will be no more resilient than an open pot of water in the desert.
Well how many grits do I use in between 60-80 and 150? The answer my industrious friend, is zero. I go straight from 80 to 150. Everything else is a waste of time. Nobody got time for that! Going from 80 to 100, to 120, to 150 sounds like 3 steps too many. 150 will take all the small ridges you made using your 80 grit, and make them just smooth enough that a finish will fill the voids and create a great bond to build upon.
So in closing, sanding is good for your wood. You only need two grits, 80 & 150 and buy extra in case you have large surfaces to take care of, so you'll have fresh sheets to use. Go from low to high, and always sand with the grain.
Thank you for reading, and next we will talk about utilizing sanding techniques between coats of finish.