I am told that there is no need to neutralize, and I haven't on my test pieces. I have not put any finish on the test pieces yet, but I am concerned that the color is too much like a "stain" or "paint", and not as clear as A.F., but I will have to see when I get around to putting some finish on.
Chris vinegar black is ferric acetate and AF is ferric nitrate - both are similar - iron in solution ith VB being Iron dissolved in acetic acid which is much more volatile so gasses off easier/faster than AF which is of course iron dissolved in nitric acid. While not necessary VB can be blushed with heat to speed the gassing off.
Here are some comparisons of VB and AF on wood -
In the first image the top piece was my control using some homemade AF that I had used for years on various projects - on the lowere part is from left to write Vinegarroon. middle is Ferric Nitrate crystals (commercially made AF basically) made 5:1 with water, on the right is some AF made by dissolving some steel in Birchwood Casey's Plum Brown which includes nitric acid as well as a couple of others - both pieces of wood were only lightly finished with home brewed linseed oil varnish:
In this image the piece on the left was stained with my home brewed AF (the control used above) - the face was left un-neutralized to show how it can darken in sunlight even when finished. The piece on the left was done with Vinegaroon the whole thing un-neutralized - both pieces were fully finished with linseed oil varnish - as you can see the vinegaroon piece is just as clear as the AF piece - the only thing I've notice is that I don't get quite the degree of chatoyance depth (that looking down into the wood that then looks like an opal) with vinegaroon as I do with AF and can only figure that the residual nitric is having more effect, but for most uses vinegar black is so close (and less dangerous to make) to AF it's hard to tell the difference.
here's an original recipe from 1875:
VINEGAR BLACK (aka Vinegaroon)
For giving color to the grain of leather there is no blacking that will at all compare with the well known vinegar black. This may be made in various ways. The simplest, and, without doubt, the best, is to procure shavings from an iron turner and cover them with pure cider vinegar; heat up and set aside for a week or two, then heat again and set in a cool place for two weeks; pour off the vinegar, allow it to stand for a few days, and draw off and cork up in bottles. This will keep for a long time, and, while producing a deep black on leather, will not stain the hands.
Note when making VB for leather rusted iron/steel is unnecessary while for wood stain it aids in getting the reddish hues.......Also heating speeds the process some what when making it, but is not absolutely necessary.......
FYI - vinegar black has been used to stain leather since at least the time of the Pharaohs and has been used to ebonize various woods since at least the early Roman Empire
