Joe Barry replies: I’ll sand up to 150 grit then wet the wood. This not only raises the grain but it brings out all those little dings that work there way into the project during assembly, it also highlights glue spots. When dry, sand to 180 then wet again and hand sand with 180. That grittiness after a few seasons is the humidity raising the grain. It is more apparent with an oil finish than with a topcoat. The reason is that a top coat lies on the surface and essentially traps those tiny wood fibers in the finish.
An oil finish penetrates the wood and cures in the wood itself. Its also not as moisture resistant as a top coat. As the oil slowly oxidizes over time it looses its grip on that fuzz and it swells up in high humid.
The same goes for Walnut however walnut is much softer and more open grained than cherry, therefore the fuzz you get after wetting will be much coarser.
Apply the oil with 400 or 600 grit wet/dry sandpaper. The abrasive will cut off the raised feathers of grain and make a slurry that will level and fill the surface of the wood. Subsequent coats can be applied with a Scotchbrite pad and then a rag.
Roy Noyes replies: I have used oil finishes on Butternut, Maple and Walnut for many years with no problems of grain raising using the following procedure:
This is the easiest finish to use and my favorite.