I am making a bent plywood desktop with a walnut veneer. This piece is intended to wow a local high end furniture store who is considering carrying my work. I want to fill the pores by sanding with oil and 400 grit paper to pack the pores with sawdust for a natural look. I have never done this with a veneer before and am wondering if I won't sand through the veneer. Have any of you ever tried this? Or have any alternate suggestions for a high-gloss, pore-filled finish that looks as natural as possible? I am using some really nice curly walnut veneer and don't want to obscure the color or grain of this wood.
From contributor R:
I think you are on the right track, but don't expect to get a high gloss finish from just wet sanding the oil. The gloss will come from the wax you use over the oil. If you're concerned about rubbing through the veneer, use a finer grit paper.
You don't need to use the dark (black) wet-dry paper for this project. You can use the grey silicone carbide paper and get good results. The oil will not soften the glues used to adhere the sanding medium to the paper. I'm sure someone will chime in about the grits being different on a wet-dry paper versus a silicone carbide paper, but don't be swayed against using the grey paper; it's cheaper and will work just fine. Come to think of it, the grits are sharper on a black paper too, but don't concern yourself with that either - use the grey paper.
I have a Porter Cable Speed-Bloc sander that's dedicated to jobs like this. Keep the surface wet with oil and slowly and evenly sand the flat areas with the machine. Hand sand the curved area with the same grit paper.
Those who are going to question the use of the grey paper vs. the black paper are also going to question the use of an electric sander along with a liquid, but in the thirty years I've done this type of finish this way, I've never had any problems, nor have any of the piano finishers who I learned this technique from. Use an air jitterbug if you want. The finish you will get from oil and wax is downright beautiful, but it does take time and a gentle touch.
After the oil has dried quite a long time, say a week or so (so being the better of the two), and you determine the oil is bone dry, apply paste wax by hand and buff it up to a fine shine (George Frank referred to this kind of sheen as a dry shine). This is a slow process (but I never sweat it) because of the dry times involved. Start waxing too soon and the solvents in the paste wax can reactivate the oils and you can end up with a huge mess. If you're interested in completely filling the grain of the walnut, make sure to start with a sharp open grain. Sharp is important. To get sharp, drag a brass bristle brush back and forth and inline with the grain to open it up. Just a bit of pressure helps. Air blast the dust from the pores before starting the oil process.