Sandpaper for stationary tools is expensive and can be ruined so quickly. Changing it is a pain in the neck, but sometimes it can be salvaged – and without a lot of work.
“Burning” occurs when sanding resinous wood. The heat generated by the sanding process liquifies the natural resins and they melt into the paper causing a streak of dark brown that eventually gets hard and shiny. It also leaves a nice streak on your wood, too. You can usually sand off the burn mark on the wood using light passes on a clean area of the sanding surface, but that streak in the paper can be a problem.
Don’t even bother with those rubbery sandpaper cleaners for this. Try a hunk of acrylic (plexiglass) plastic. I have a small piece, about 4″ x 4″ x 3/8″. I keep it with that rubbery thing and use it when I first start seeing a resin streak. Turn on the sander and press the edge of the plastic into the sanding belt. Move it around, varying the angle and moving side to side looking for the best position to scrape away the burn.
It helps, but the streak will never completely go away. I keep shifting my wood piece to a new spot on the sander, but eventually the belt just has to go!
Cleaning Burned Sandpaper
Now, I’m lazy. I don’t want to elbow grease my problem away, I want to use the miracle of chemistry to do it for me. So this is my solution, literally.
I keep a bucket of this in my shop at all times. I dunk saw blades in here to get rid of the resin on them, so I thought, why not sandpaper? The worst that could happen is the glue also dissolves and you have sandless paper.
This solution is about 5:1, water:Simple Green. You can reuse it over and over, so that same bucket will be usable for months.
Soak it, Scrub it, Dry it
I soaked the sandpaper in the bucket overnight, then I put it in the utility sink, rinse it, and scrub it lightly with a tooth brush. You really don’t have to scrub much. If it weren’t so gritty, you could probably just wipe it with a rag.
Then I set it to dry, sort of in the form it should be instead of all tangled up.
It dried nicely and very clean. Not much work at all. Next time I need this grit, it goes on the sander.