Making your own AF Nitric Acid Stain

[Top Jaw]

I have about 6 ounces of 70% concentrated nitric acid. Wanting to make a batch of AF stain. 

Now I know there are some safety precautions to this. Do it outdoors up wind. Add the acid to the water, not the other way around. Have it in a container that will stand some heat (pyrex glass or a crock). Add metal, steel wool, etc., slowly, until it stops reacting.  Wear nitrile gloves.   Don’t breath any fumes!

My main question is what ratios have some of you used?   I was thinking 3:1 (water to acid) to start with.   Any personal experience to share, or lessons learned?  How long will a batch keep in a cool dark place in an amber bottle & lid?

Brian

[P.Bigham]

I've done it 4 or 5 to 1.  Slowly added cleaned finish nails of all oils til the acid is finished. Then strain it through cheese cloth. Done with well water.  Done it slowly over time doesn't heat up much.  Lasts quite a while out of sunshine.

[Not English]

Brian, I knock it down to about a 30% percent solution, which is still plenty strong. one application is plenty usually. You won't err by going weaker. It just may take more applications. Aqua Fortis is notoriously hard to control the color, so weaker solutions may be of help. I keep mine in glass bottles and jars in  the basement and have not noticed any sort of shelf life when stored.

Dave

[davec2]

Top Jaw,

Send me an email and I will send back a copy of Bill Knight's directions for preparing iron nitrate stain from acid.  He sent it to me as an excerpt from the book he and Bill Mende wrote on 18th century staining and finishing techniques......

[bluenoser]

Bill was a tremendous resource and is sorely missed.  Please tell us more about this book.

[Bill Raby]

What is the other 30%?

[smallpatch]

Wow, I love using aqua fortis for staining maple, (among other uses), but with products available today, (ferric nitrate in crystal form) , I just don’t understand the need to make your own.
Sorry to be negative.

[longcruise]

Wow, I love using aqua fortis for staining maple, (among other uses), but with products available today, (ferric nitrate in crystal form) , I just don’t understand the need to make your own.
Sorry to be negative.

Agree.  Done it with home made and ferric nitrate  crystals.  So much simpler.

On top of that,  the  acid ate through the bottles cap and suddenly tools began to rust and bright shiny aluminum objects turned gray.  Never again!

[Scota4570]

What is the other 30%?

VC * MC = VD * MD
500ml * 70%  = X  * 30%
500 * .7 / .3
1166 total volume
Dilute up to that by slowly adding 500ML of acid slowly to 666 ml distilled water. 
I’d try to dissuade doing this  without proper glassware and safety gear.  Please wear a face shield, please have a garden hose or shower on your radar screen before you start.  Have a large container of baking soda hand to neutralize any spills. 

I bought a container of ferric nitrate crystals, done, easy, safe works........I worked in a laboratory for 30 years and working with dangerous chemicals was part of my job.  I do not make my own at home. 

[davec2]

Bluenoser,

Here is the book by Bill Knight and Bill Mende.  I don't know where a copy might be found.  It contains much more about finishing and staining than just making iron nitrate stain.....coloring and preserving horn, how to make oil cloth, how to make boiled oil finishes, etc., etc.



Top Jaw,

By the way, I agree with the others that if you only need the stain for stocks, the solution can much more easily be made up from iron nitrate crystals and either water or alcohol.  I use a lot of nitric acid for many other things (i.e. dissolving gold, etching copper or silver, nitrating cellulose, etc.) so I have it around.  I also use it as a wood stain by itself.  It does a lovely job of staining maple even without the iron... just much lighter finished color without the iron.

[Top Jaw]

A buddy gave me about 6 ounces of nitric acid. It’s been in a cupboard in my shop (away from iron tools) for quite some time. I wanted to make iron nitrate stain from it, to put it in a more stable condition, and because it was drilled into me from a young age by farming Grandparents that lived through the Great Depression - that you should not waste perfectly good things. Even when it is nitric acid. 🧪☁️💥.  I completely understand that ferric nitrate crystals are the preferred way to go. But no one gave me any of those that I need to do something with.  😃. I will take precautions.  Thank you all for the valid concerns.

[StevenV]

Attached are some photos of when I made some Aqua Fortis back in 2014. The other pic is of the stain today, along with some from a guy named Kettenburg  from 2003. I keep it on a shelf in the cellar out of the sun , as good today as it was in 2003/2014 . I did make mine outside and various concentrations. If I were to make just one it would be 4:1. I use 4:1 and 6:1 when staining. If concentration is too high( gun not accepting/absorbing stain) wet your gun a bit and then rub on the Fortis with cloth. This will help with absorption( tip from Bill Knight). Continue to add iron ( I had wrought iron chips) add again once the amount you added the previous day is gone. Continue to add until the iron is still visible for a couple of days. This means acid is spent, now you have a solution with iron dissolved in it not and a nitric acid stain. The acid is spent. Love it , only stain I use , zero problems with it. As I see in your post you are aware of acid to water, not water to acid. I used gloves but not respirator as it was outside and keep face out of harms way. Googles or safety glass might not be a bad idea, or just keep face out of harms way. I even went so far as to add ice to reaction (added ice to water that your jar your using to dissolve iron is sitting in). This is just to keep reaction cool. Not sure it was necessary, but did it anyway. Ice does not go in your jar your adding acid to it goes in the ice bath your jar is sitting in to keep reaction cool.  Steve

[wapiti22]

There is a copy of the above mentioned book on EBay. $250.00 + shipping.

[Dphariss]

Cut the acid you have about 50-50 distilled water. Use a STONEWARE pitcher. There may be significant heat. Add iron until the acid is depleted. Like the next day and the next too.  No kids or pets anywhere around.
Add acid to water not water to acid.
Any iron source will work, old iron wagon tire or new nails all give the same color. Just degrease the nails or what ever.
Do it outside. Expect a plume of orange fumes.
Wear head to foot protective gear. One drop in your eye and the eye is toast forever.
Nitric is really nasty stuff and even diluted its very aggressive.
I tell people to us ferric nitrate crystals instead. No acid, same color when mixed right.

[Scota4570]

I'd love to own the book by Bill Knight and Bill Mende not @ $250 though.  I miss corresponding with Bill Knight, he was great at satisfying my desire to get into the weeds on various technical subjects. 

[bluenoser]

MAN, I do want a copy of that book, but think I will have to pass at $250.00US.  That must be about $15,000.00C
I do have all of Bill's posts I could find saved in a word doc.

[davec2]

Does anyone have contact with Bill Mende ?

[Top Jaw]

Interesting tip about wetting the stock before the AF stain, to increase penetration.  Luthiers will often wet a crack on an instrument repair before gluing it to increase the capillary flow and penetration of the glue. Makes sense it would do something similar for AF stain.

[RAT]

When made at our gunmakers fairs, the container in which it was mixed was placed in a large glass bowl of ice to keep it cool.

[Scota4570]

Guys please be careful. 

Food and canning jars are not suitable exothermic chemical reaction vessels.   There is a chance the jar will shatter from the heat and then you have a huge mess of acid to clean up.  IT will take several pounds of baking soda to neutralize it.  Another  consideration is that the metal lid will dissolve quickly in storage. 

Real chemical storage containers are heavy duty pyrex with a thick chemical resistant lid and lid liner.  Reactions should be  performed in proper laboratory glassware and in a fume hood. 

[Daryl]

Decades ago, I used nitric acid as a browning agent. I don't remember what I stored it in or if I cut it with water, but I dissolved a bunch of nails in it.
Hard to get it to stop rusting, and my fingers throbbed for a year or so. I also developed a condition of "thick-skin syndrome" or something like that. It
of course was my body reaction to the acid. I had to sand my trigger finger often, just to feel the trigger - the belt sander did a good job of that. Over it now, hands
as soft as a baby's tush (well, softer than they were for years)
That's back when I was young and impervious to danger.
Yes, be careful out there.