What kind of finish will not darken walnut? I'm doing one in Claro Walnut. Crazy wood to work with. Grain goes every where. I would like to keep it as natural as possible. I've done various tests on scraps with out much luck. Seems that any oil base goes real dark. The bare wood is lighter than American walnut and has various shades of grey in it like minerals. The only thing I've tried that comes close is a water base poly urethane shelack. Thought maybe doing several coats of that and then a boiled linseed thinking the shelack will prevent the oil from soaking in.
Dave Waters
Varathane is your best bet. Will look like $#@*, sorta like the figure was painted on, it may even reduce the color contrast, but will not darken the wood much. The finish will likely fail if the firearms is actually used much, but maybe not plastic can be pretty amazing, but I doubt its elastic enough.
I would use my home boiled linseed but thats just me. I like the figure being enhanced.
This walnut 2x4 was not polished at all just as I had milled it with a fly cutter.
Varathane is the light stuff upper left. But it did nothing to bring out any of the hidden color or figure in the wood.
Concerning excessively darkened stocks.
Regardless of what some store bought finish may do a
properly prepared linseed oil based finish will not continue to darken once its set. Most stocks, such as English Walnut, will show little darkening on first application but will darken somewhat over about a week then stabilize and will show more figure and better color tone.
So far as stock finish having acetic acid added, one of the purposes of heat modifying linseed oil is to add something to reduce the natural acids in the oil. Adding acid to the finish makes no sense since highly acidic materials put on/in a stock may well turn it black over time . But then there are a lot of things added to over the counter finishes that make little sense.
I would also point out that most of the gunsmiths manuals, Howe or anyone else need someone who knows more than the writer to sift the voodoo and myth from the actual usable material. I quit paying attention to them !@*%&@ near 30 years ago figuring out that is was mostly BS from the standpoint of ease off application and tradition.
I loved the one I read in "Gunsmith Kinks" a couple of months ago in which the guy recommended smearing chassis grease on a LS finish that was not drying saying it would be found to be dry when the grease was wiped off the next AM.
In reality the petroleum oil (it is just oil with thickeners afterall) in the grease acts as a solvent and simply removes the uncured LS oil.
Dan