I smooth polyurethane with 600-grit wet and dry sandpaper lubricated with furniture oil instead of water. Is this a good idea?
Greg Williams: That depends on what you mean by furniture oil. If you mean a coating material, such as a “teak oil finish,} it will leave a film on the coating being sanded that might be difficult to remove. If it is an oil polish, it is an expensive way to lubricate the sandpaper, and again, will need to be removed with a solvent. What you are trying to do is to prevent the sandpaper from loading up, and reduce friction, to reduce labor and heat buildup. Water by itself is not sufficiently lubricious for most wood coatings, but water with a vegetable-based lubricant, such as Wool-Lube™ or flax soap added, will cost less, be less messy, less smelly, non-flammable, and easier to clean up. A small amount will make the water slippery, and keep the sanded-off particles from adhering to the abrasive. When you are done, simply wipe dry.