When working with walnut, sand to the desired grit and raise the grain by rubbing over the wood with a very damp, not wet, lint free cloth. Use a hair dryer to quick dry the wood, which will raise any cut grain...for the traditionalists, use the heat from your coal forge to raise the grain... Do this a couple of times without sanding.
Next, take a teaspoon or so of your stock finish and put it into a shallow dish. I like to use the plastic lids from cans of coffee. Using a sanding block with 400 grit wet-or-dry, wet the sandpaper with your finish and start sanding down the grain with the wet paper, going with the grain. You'll create a slurry of very fine sawdust and finish that should be rubbed across the grain with the heel of your hand as you finish each small section of stock. When done, let it dry for several days, re-sand back to the level surface (some slurry will be above surface) and again wet sand. If your walnut is very open grained, do this a third time, though it is not normally needed.
After this last coat of finish-slurry has fully dried, very lightly dry sand it and put on one or two coats of finish as top coats, hand rubbed in. You're filling the grain with the stock wood sawdust, so color will not change, and if you do any checkering on the stock, the filler will not dull your tools. Be sure to let the finish dry completely when using this method. Works with modern finishes as well as thinned down boiled linseed oil and tung oil.
When talking about dry with this method, I mean fully hard and dry, not just dry to the touch. Depending on heat and humidity, it can take a couple of days or a couple of weeks.
David
(That's my story and I'm sticking to it!)
