Neutralizing aqufortis

[Eric Krewson]

I have been testing different combinations of aqufortis and other stains.I really like plain aqufortis neutralized with a dilute lye solution.



I had read one needs to neutralize the lye with vinegar so I gave this a try and my beautiful color turned almost black when I applied the vinegar.



Does one really need to neutralize the dilute lye?

My aqufortis is the commercial kind from Track.

[Stophel]

"Does one really need to neutralize the dilute lye?"

No.

Just wash the stock off with water.

 

[FG1]

I wash with a weak solution of baking soda and water to kill the acid and to keep it from turning green then a clear water rince. Wakon Bay Aquafortis is what I have been using.

[Black Hand]

You could neutralize the AF with a paste of baking soda and water.  Let sit for a few minutes, rinse off with water and allow to dry.

[Bioprof]

Aquafortis is acidic if insufficient iron is added.   The lye is a strong base.   The lye or baking soda is supposed to neutralize the acid in the aquafortis.  If you add vinegar, you are just undoing the neutralization that you did with the lye or baking soda.

[M.D.H.]

Aqua fortis, or what every one referrs to is actually Nitric Ferris or Nitric of Iron.  To make an educated decision, you need to understand what your dealing with.  

True Nitric Ferris is the result of mixing Nitric Acid and distilled water, then adding wrought iron to the solution.  The iron is dissolved by the mixture through the reaction of the acid and the iron, known as corrosion or oxidation (basically rust).  

When done, meaning the acid will no longer dissolve any more iron, you have Nitric Ferris. At this point the "Acid" is spent.  Meaning it is now Neutral and has no more reactionary qualities to the Iron.

To neutralize an acid, you use a "Base" such as  baking soda.  And by my understanding, that is what certain builders are referring to.  However, if you have "nitric ferris", you solution is already neutrealized.  So by adding baking soda,  you are accomplishing little.  The other thing you need to keep in mind, is that the Nitric Ferris will react to the "tannins" in the wood.  And that can vary from one end of a blank to the other.    

I've been lucky to work a fair amount with Nitric Ferris.  And I'm by no means an expert, but my results have been very pleasing to me.  So take that at what it is.  The best book I can recommend is by Bill Mende  and Bill Knight called "Staining and Finishing for Muzzeloading Gun Builders - Method and Materials from 1750-1850"  Great read, and Bill Mende is very forthcoming with help.

Good luck.
M
  

[Eric Krewson]

I have done a bunch of different tests with aqfortis and noticed when I use the dilute lye wash over the blushed aqfortis it changes the color from a coconut brown to a reddish brown. 

[BillC]

When done, meaning the acid will no longer dissolve any more iron, you have Nitric Ferris. At this point the "Acid" is spent.  Meaning it is now Neutral and has no more reactionary qualities to the Iron.
 
[/quote]

While I will take your word that this ideal situation is true I can testify that the Wakon Bay solution that many of us use is not neutral. Applying the bakeing soda solution causes a definate reaction (bubbles). This indicates remaining acid.
Bill

[b bogart]

This may be a STUPID question, but after all look who's asking.
Could a guy just purchase Nitric ferris instead of all that concotion mixing?  Please tell me what the difference would be.  I hope this isn't veering off topic.
Bruce

[Dphariss]

This may be a STUPID question, but after all look who's asking.
Could a guy just purchase Nitric ferris instead of all that concotion mixing?  Please tell me what the difference would be.  I hope this isn't veering off topic.
Bruce

Yes. Think its sold as ferric nitrate crystals. But I have a lifetime supply of nitric so I make the stuff.
Found an old spring wagon/buckboard tire last year that will supply iron.
Dan

[Dphariss]

I wash with a weak solution of baking soda and water to kill the acid and to keep it from turning green then a clear water rince. Wakon Bay Aquafortis is what I have been using.

Actually it just get darker and darker. I under neutralized some Wakon BAy stuff about 12 years ago and its getting pretty muddy looking. May sand it, restain and go from there.
I tend to use a pretty stiff mix of soda now all the warm water will dissolve. But my home made stuff is lower in acid and I keep adding metal to it all the time.

Dan

[Darkhorse]

First question; If the store bought stuff is still acidic why couldn't you add more iron until it is not acidic.
Second question; How does Mr. Hershall House get away with dissolving steel wool in his nitric acid instead of iron?
Third question; I didn't think you could buy true nitric acid from the ML supply houses over the internet anymore. Can you?

[eagle24]

First question; If the store bought stuff is still acidic why couldn't you add more iron until it is not acidic.
Second question; How does Mr. Hershall House get away with dissolving steel wool in his nitric acid instead of iron?
Third question; I didn't think you could buy true nitric acid from the ML supply houses over the internet anymore. Can you?

First, I had a very respected builder tell me at the CLA show that if you use the "store bought" AF you can dissolve more iron or steel until it is spent.
Second, I used steel wool to make my AF from Nitric Acid and was pleased with the outcome.  Washed it with denatured alcohol first and let it dry thoroughly.
Third, You can still buy Nitric Acid.  I bought some semi conductor grade nitric from a chemical comany in CA (69%).  Shipping is expensive, but you can get it.

[stuart cee dub]

Another readily available neutralizer is club soda.Baking soda if too strong will turn a stock green.Learned that the hard way . 

[Dphariss]

First question; If the store bought stuff is still acidic why couldn't you add more iron until it is not acidic.
Second question; How does Mr. Hershall House get away with dissolving steel wool in his nitric acid instead of iron?
Third question; I didn't think you could buy true nitric acid from the ML supply houses over the internet anymore. Can you?

First some of the store bought stuff contains hydrochloric which a friend claims muddies the grain.
You can buy nitric from chemical supply houses but it requires a hazmat shipping charge IIRC.
The easiest way is to buy ferric nitrate crystals and mix with water.

Dan

[tallbear]

Wahkon Bay aqua-fortis is really aqua-regia, which is a mixture of nitric acid,hydrochloric acid and water with iron added.I've never had any trouble with it muddying the grain but it  tends to be very acidic and needs to be neutralized.I use household ammonia as it doesn't seem to raise the grain as much as the bakeing soda and water .You can dissolve more iron into it to decrease the acidity if you like.Neutralizing can change the color which can add to your color palate.
Steel wool works to make aqua-fortis but causes a violent reaction but it will work.
I have a whole bunch of different mixes of aqua-fortis and some Wahkon aqua-regia.They all produce different colors on the same wood.You can also neutralize to get different colors yet.I play with them all to get the color I'm looking for hopefully .

Mitch

[Eric Krewson]

The deed is done and is strikingly  beautiful if the water rinsing of the lye is any indication. I did have a light patch about the size of a silver dollar near the butt plate after the process was complete I applied more aqufortis, neutralized and rinsed, then I had a darker place in place of the formerly lighter section. I very lightly sanded this dark patch until it lightened and blended in perfectly.

[Randall Steffy]

Eric,
As my grand-daddy would have said of a quick study or learner, "There are no flies on you."

[doug]

     some people use nitric acid only to stain the wood.  My impression is that it is cut to somewhere between 30% and 50% acid and it will more or less burn the wood brown.  I personally cut the acid to about 30% and then add steel wool until it will dissolve no more and I don't bother neutralizing.  It would seem that there is more than one process meant by the term aqua fortis staining

cheers Doug

[Dr. Tim-Boone]

I found that the easy way is to buy Ferric Nitrate crystals from the Science Store online. mix it in a pretty strong solutions of 2 parts distilled water and 1 part crystals (by volume) up to 50/50. I have been doing some experimenting and find it works very well. It is non acidic/neutral so no neutralizing is needed.  I don't like playing with acid....... if I don't have to.  

[Dphariss]

 I don't like playing with acid....... if I don't have to.  

Every time I put iron in the diluted nitric I wonder if its worth it.

Dan

[Chuck Burrows]

As sample of four acid based stains - the finish is two coats of real boiled linseed oil based varnish:
top piece is from an old bottle of Wahkon Bay AF used as a control:
Bottom:
left: iron and vinegar aka ferric acetate
center: Ferric Nitrate crystals - 3:1 water to crystals
right: home made AF using BC Plum Brown as the source of the nitric (10% nitric - it has 3 other acids as well) and steel wool - somebody said it worked so I tried it..



Not the best image, but all four are very similar as to color - the only noticeable difference to my eye when looking at the actual wood, is the vinegar based doesn't have quite the depth/opalescence as the nitric based stains.
FWIW - I've been using acid based stains and real boiled linseed oil/varnish for 40 years and for those who prefer a somewhat less hazardous method the Ferric Nitrate crystals or the vinegar based mix work great without dealing with raw nitric - I've also used the newer version of Wahkon Bay and find it will take some more iron which is not a bad thing - just do it with plenty of ventilation - outside is best.

Found another pic - WB AF on the left (notice the front face - it turned darker becuase I didn't neutralize) - piece on the right is Ferric Nitrate crystals:

[Eric Krewson]

I thought I would post this picture for people who haven't used aqufortis to show the way it looks before and after blushing with heat. The green side is before.

[Stophel]

Thank you for showing that.  A lot of people see the green and freak out.

Sometimes the wood turns gray, by the way, depending upon the particular piece of wood.

[eagle24]

A lot of people see the green and freak out.

^^Me^^