What finish has the least effect on wood color?

Yeah, wax.

Super-blonde shellac doesn’t shift color much.

The various higher-grade poly’s like Varathane Elite are
less cloudy than lower grade polys. The average person
can’t see the difference but all poly is a bit cloudy. Still,
the color shift is insignificant. Clarity is hard to judge
as well and my perception of Varathane Elite as more
clear than Minwax poly may be my own fantasy.

Then there’s lacquer.

My lacquering is limited to spray cans :) but my projects are all small items so that is an option. Thanks for the tips on poly.

-- I'll grow up when ketchup bottle farts stop being funny.

Depends on the wood, BLO on Maple and Pine only bring out a soft yellow tinge.

I have had great success with rattle can lacquer and recently Deft has come out with a new can(blue in color vs. green) I thought to myself, there will be no difference. I was wrong that new can spays almost as well as HVLP IMHO.

-- Patrick, Helicopters don't fly. They beat the air into submission.

Osmo Polyx oil clear is as transparent as you can get. Acrylic varnishes won’t impart an amber hue either.
I have sprayed a clear matt acrylic varnish straight out of the tin with my HVLP sprayer and the finish was perfect.

-- Do or do not, there is no try

Thanks for the tips, everybody. I’m going to look into all these options as time allows. Wish I had the space for an HVLP setup.. maybe one day :). Top of my list is trying out the new Deft spray-can lacquer (HawkDiver) that I didn’t know about.

-- I'll grow up when ketchup bottle farts stop being funny.

I have been using Deft Clear Wood Finish since discovering it back in the early 80’s. Clear lacquer (and now available in water base). Dries fast and makes for a good looking finish. I used it previously to seal wood craft projects that my wife had painted patterns on with acrylic paints. No runs, discoloration or anything.

Any varnish or spar.

-- Failure does not stop me, it makes me try harder..... because I'm crazy.

Water based poly doesn’t change the color much, about what the wood looks like when you wet it with water.

Water based poly for sure.

-- Charlie M. "Woodworking - patience = firewood"

Crystalac water borne poly. No color at all.

-- He who dies with the most tools... dies with the emptiest wallet.