Acid Recipe for curly Maple

A solution of Lye and water works extremely well on Cherry, have not tried other woods but I think it would work for them as well.
 
Dissolving iron in nitric acid produces ferric nitrate which can be bought pre-made from:

A) WAHKON BAY AQUAFORTIS 2 oz. $8.95.
Continental U.S. ground shipping only.
Gunbuilder and dealer quantities available.
MICHAEL LEA AND DAUGHTER
2109 Summit Street
Columbus OH 43201.
Telephone 614-291-4757, email <oldguns2109@sbcglobal.net>

B) or you can buy Ferric Nitrate crystals on line from the Science Company - mix 3:1 water to the crystals

C) or you can make ferric acetate - iron dissolved in vinegar (acetic acid)
My method: I use degreased steel wool frequently for convenience and I've had no problems with weird colors due to alloying elements as some others have stated may happen. Rusty iron can also be used - it will usually increase the red tones to the finished product,
1) Degrease the steel wool and tear it into small piece - this gives more surface area for the acetic acid in the vinegar to work on.
2) Add one pad of SW to a quart of vinegar (I prefer cider but white works) - you can increase the amount - just use the same ratio
3) Bring to a boil and turn off - let cool
4) Pour into a container - I use those plastic coffee "cans" with a SMALL hole in the top to vent off any excess gas
5) Stir now and again and if all of the iron is dissolved add a bit more - the idea is to use up all of the acid. You will know this when no more iron will dissolve and the typical vinegar odor is gone or mild at most. If after adding more iron it turns "rusty" leave as is or add some more vinegar to "clear" it.
6) Heat again at times if you choose - the heat will accelerate the process - unlike the original I often leave my mix in a sunny window.
7) Once no more iron dissolves - siphon/filter off the liquid - save the dregs to start your next batch......It seldom takes more than a month for me to make a batch and if you keep a spare going you never run out.............


D) Some notes: in the old days pure nitric acid was known as Aqua Fortis, later the ferric nitrate mix made by dissolving iron in nitric acid was also called Aqua Fortis. The use of the same name for both products can be confusing when reading the old literature.

"You want to be sure and give the acid enough time to kill itself eating the iron before applying to the wood. ."
It SHOULD kill the acid but doesn't always so neutralizing when using AF is a good idea. Wallace G and all the other top muzzleloader smiths that I know of who use it neutralize and with all due respect to Wallace, and those interested in the past have a lot to thank him and the other W'Burg smiths for, like Damascus the technique was never lost, Hacker Martin and other old time smiths as well as other types of woodworkers, had continued to use AF all along - Wallace was one of the first to write about it and thus spread the info to a wider audience). Liquid Potash or ammonia will neutralize.
Even when using the commercially prepared Ferric Nitrate crystals available from scientific supply companies (which is very pure stuff) I've found requires neutralizing or the stock will USUALLY darken.
Here's an example of darkening - the piece on the left was neutralized only on the top after using AF - notice how the vertical face is much darker due to not being neutralized and then exposed to the sun:
maple-001.jpg


To bring out the best grain heat is required - most folks use a paint stripper. The major reason is to make any remaining nitric acid more volatile so it will off gas, but it also blushes the wood and increases the chatoyance.

As noted above you can get virtually the same effect as Aqua Fortis aka ferric nitrate with ferric acetate, iron dissolved in vinegar, but due to the higher volatility of the acetic acid in vinegar there is no need to heat or neutralize.

Some examples of both Ferric Nitrate and Ferric Acetate:
DSC00126.jpg


The top piece was done with some old Wahkon Bay AF as a control. On the lower piece three different mixes were used:
left - ferric acetate aka iron dissolved in vinegar
center - commercially prepared ferric nitrate crystals dissolved in distilled water which "makes" Aqua Fortis; they are available from the Science Company and other suppliers
right - ferric nitrate aka Aqua Fortis made by dissolving degreased steel wool in a bottle of Birchwood Casey Plum Brown, which is 10% nitric plus other acids (if you do this do it OUTSIDE with PLENTY of ventilation and in a large Pyrex bowl along with chemical rubber gloves, eye protection, and a good mask).


When using either Ferric Nitrate or Ferric Acetate you can increase the effect of using them by first wetting down with a STRONG black tea mix - the extra tannins react with the "dye" and can really make the grain pop.


Some examples of finished pieces - All pieces of wood above and below were finished with a homemade period linseed oil based varnish (it's nothing like hardware BLO).

pipehawk-pulich-1-5.jpg


cr-32-3.jpg
cr-32-4.jpg


cr-20-iw-006.jpg


And pictures really don't do this method justice...........when holding it in your hand in nice light and with high end wood, it's like looking down into a fire opal.....and each piece of wood will respond differently as can be seen above......

I use chromic acid from RWWilson. Does the same thing as the other acid mixes.
Bruce I kind of hate to say this, but chromic acid was widely used by muzzleloader smiths in the 1970's and in almost all cases they found that after a few years the color turned an often vivid green. For that reason I don't know of any experienced smith (except RW), and I know plenty, who will use it today.
In fact for those looking for more info on Aqua Fortis aka ferric or iron nitrate, visit the American Long Rifles forum (http://americanlongrifles.org/forum/index.php) and do a search for those terms......
Some of the best and most experienced muzzleloader smiths hang their hat there and freely offer their expertise
 
Chuck, I haven't had any of that problem.... yet. Might be 'cause I'm always topping it off with some other stain/mixture. Leather dye, alcohol based wood dye, John Richards Walnut mix, etc.
Thanks for pointing that out. bruce
 
I have what I was told when purchased to be some curly hickory. Would this acid finish work well for curly hickory (and is that indeed what I have, if you can tell from the picture?)

Also, the scale on the left side is un-sanded while the one on the right is sanded to 120x. I would have expected the curl to be more evident as the finish gets finer but the opposite is happening...is this normal for curly wood?

Thanks in advance for any help!
 

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I have a rifle making friend that is having green tents coming out when he uses aqua fortis. Is the guy he is buying from selling him something else? Ed
 
Ed, is your friend heating the wood after the aqua fortis dries? It goes on sort of yellow to light green, and when you heat it with a torch or hot air gun, it turns darker and lighter browns.
 
Ed, is your friend heating the wood after the aqua fortis dries? It goes on sort of yellow to light green, and when you heat it with a torch or hot air gun, it turns darker and lighter browns.
He was heating it and it looked good, It started turning greenish a good while later. Thanks Ed
 
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