Sandpaper leaving dark marks on wood

[Perry Hilbert Jr]

OP didn't say what kind of wood. For instance maple,, seems it develops surface scorching very easily. Some other woods are most likely the same. 1200 grit paper can gum up easily from natural oils and saw dust on the wood. then it just burnishes and burns. I don't sand some woods beyond 400 until after a coat of sanding sealer. Then a 600 grit to even out the sanding sealer. And maybe another coat and then the high grits to polish the finish. I have been turning a lot of bass and tulip poplar, both very soft and sanding beyond 400 grit doesn't seem to get much, except to burnish the surface. A coat of sanding sealer seems to harden the surface of the softer woods and then a nice glassy finish can be achieved. I don't have a lot of experience turning either, but from other wood working I came to realize that different woods have different "personalities." What works on one, doesn't necessarily work on another. Some contain a high amount of natural oils, teak for instance. decades ago I turned dozens of bowls from Teak. The beauty of it was that to get a nice glossy finish, all I had to do was hold a rag up against the wood and the heat would bring the oil to the surface and "bake" it on the surface. Looked like a finish with no finish being used. Some pine has resins that get hard as rock after a few years. (Dade county pine, an endangered species now I understand) Other pine is soft and and dry. Sassafras branches and roots contain a lot of oil. The trunk wood often has to have cracks partially around the interior rings because the rings can actually separate in a living tree when it flexes in heavy winds. Some oak is subject to having the fibers between rings tear our when turning, and it leaves a corduroy effect on end grain surfaces. Just throwing that out there. Could be the wood, and not the abrasives.

[Jim Fulbright]

No, not steel wool. I have noticed it on several woods that are lighter, not just the oak. I bit the bullet and ordered some new sandpaper, so let's hope that that coupled with not touching any bushings will alleviate this!

[Reed Gray]

Well, the wood and the abrasives could both be the problem... Sounds like you got the idea that high speed is not good. One reason is to get the abrasives to cut, you need traction, so think of a dragster. They burn off their tires to generate heat and smoke, but they are going no where. So if you stay in the proper speed ranges, then you get good cutting and no heat. Another cause of heat is pushing too hard. If your fingers are getting warm or hot, then that is too high of a speed and/or too much pressure.

Looking at the wood, you have spots, like Leo pointed out. With an open grain wood, the pores will fill in with what ever (try buffing ash with a pad that was used for black walnut, I like that effect). So, that wood appears to be open grained, and the fill in could be part of the problem. With abrasives, I never use the cheap ones, and learned that a long time ago. You pay less, and you get less. Money well spent.

robo hippy

[Jim Fulbright]

Thank you all for your help. I've upgraded sandpaper, used it like somebody else paid for it, and have tried staying away from the bushings. I tried covering the bushings in CA glue and then masking tape. Turned out to be much more trouble than it's worth. So far, with the new sandpaper and staying away from the bushings, my pens have been turning out much better. Thanks again for everybody's help!

[Bill Boehme]

John, I apologize I completely missed your reply. The sandpaper I'm using is Warrior Wet/Dry from Harbor Freight.

The sandpaper is the problem. The wet/dry paper is silicon carbide and is meant for sanding metal, not wood. The black grit gets embeded in the wood and there's nothing that you can do to remove it. Use aluminum oxide paper or ceramic paper designed for wood. And, cheap paper equals cheap results.