ferric acetate aka vinegaroon it works in much the same way and gives much the same effect as the traditional Aqua Fortis (aka ferric nitrate) but there is no heat involved:
Take a wad or two of 3/0 steel wool and degrease it (wash in hot soapy water or to get it rusty soak in acetone - let air dry for a few minutes and light with a match to burn off any remaining acetone residue - do it in an old pan with a lid so you can put it out if need be. You can also use old rusty wire, nails, etc.
Dissolve the rusty iron in a quart of apple cider vinegar - bring it to a boil and then turn off. when cool put it in a jar with a loose lid and let set for a week or two until as much of the iron as possible is dissolved. You can re-heat, etc every 3-4 days to speed up the reaction or set it out in the hot sun - just make sure the lid is loose enough to let it off gas.
Strain off the liquid and apply to your maple - slop it on and let dry. Apply a second coat and let dry. Using scrub pads or fine sandpaper to de-whisker if need be. Once dry burnish the wood - first with a coarse cloth (canvas or old jeans) then with a smooth piece of antler or bone.
IMO the best finish is a good oil based finish - the commercial product closest to the old time oil varnishes is Tried and True Oil Varnish.
Apply sparingly and let dry completely between coats. Keep applying until you're satisfied with the finish - top off with a good coat of wax if desired.
Done right this will bring out the grain/beauty in maple like no other finish (except AF) -
Kind of like this:
or this
Done right it's like looking down into an opal - my images don't really do this type finish justice - plus it's cheap! :grin:
Other stains work good, but just never quite get that opalescence that the acid stains do, especially when followed with a good oil based finish.....
as always others mileage will vary.....