Neutralizing Aqua Fortis with Ammonia

[moleeyes36]

I'm about to do another stock with aqua fortis and have always used baking soda and water to neutralize the AF after the process is complete.  I'm thinking about trying ammonia this time as many of you do but I have some questions on using it. 

Do you just wet the wood with it and let it air dry?  Do you rinse it off with water after letting it work on the wood for a few minutes?  It seems to me that if you didn't wash it off, the stock would stink to high heaven.  Not what I want on a hunting rifle.  What is the process for using ammonia to neutralize aqua fortis?  Thanks.

Mole Eyes

[tallbear]

I wipe it on with a rag and let it dry completely before putting my sealer(seedlac) on.

Mitch

[E.vonAschwege]

I do the same as Mitch - wipe it on with a rag and let it dry off.  I usually do this right after heating, so the stock is warm enough that it doesn't take long to dry at all.  When its dry, the smell is gone.  I will sometimes wipe the stock with warm water once the ammonia is applied, I don't know why, no rhyme or reason, just what I've done before - probably don't need to.  Again, as with ammonia, we're not slopping it on, it's a once over quick wipe down. 
-Eric

[moleeyes36]

Thanks for the information, guys.  The process sounds pretty straightforward; I'll give it try.

Mole Eyes

[Mad Monk]

A bit of info here.
I am assuming you guys are talking about using household ammonia.

In the furniture factories in the late 1800's into the early 1900's they used ammonia to color certain types of woods used in furniture.  When the piece of furniture was completed and ready to be varnished it would go in a room.  Industrial strength ammonia was poured into a pan.  A fan was used to blow air over the pan containing the ammonia and circulate the fumes around the room full of furniture.  The ammonia would react with certain chemicals found naturally in the wood.  Mainly the tannins.  Oak turned the famous Golden Oak color seen in the adds.  Ash would turn something of a golden color.  Cherry wood would turn a redish brown color.

I played with that with my lathe turned powder horn plugs.  Two days in a jar with full strength ammonia gave me what looked like curly charcoal!

If the aqua fortis is properly prepared you really don't have to use a caustic on the wood, after staining.  Simple gentle heat will do the job.  With a properly prepared aqua fortis solution you have no live acid in the stain solution.  Now if you use the version of the stain where you are working with what would be a diluted acid with a little bit of iron "for color" then you must go with a caustic.

Mad Monk

[moleeyes36]

...If the aqua fortis is properly prepared you really don't have to use a caustic on the wood, after staining.  Simple gentle heat will do the job.  With a properly prepared aqua fortis solution you have no live acid in the stain solution.  Now if you use the version of the stain where you are working with what would be a diluted acid with a little bit of iron "for color" then you must go with a caustic.

Mad Monk

Unfortunately, the commercially available versions I've tried are hotter than a fire cracker and have to be neutralized after applying.  I know exactly what you mean when you say "curly charcoal", I learned the hard way by not neutralizing Wahkon Bay aqua fortis the first time I used it. 

I've thought about trying to dissolve some filings from a nail in it to see it that would "tame" it some, but I haven't tried it.

Mole Eyes

[E.vonAschwege]

Unfortunately, the commercially available versions I've tried are hotter than a fire cracker and have to be neutralized after applying.  I know exactly what you mean when you say "curly charcoal", I learned the hard way by not neutralizing Wahkon Bay aqua fortis the first time I used it. 

I've thought about trying to dissolve some filings from a nail in it to see it that would "tame" it some, but I haven't tried it.

Mole Eyes

MoleEyes - I've added water and dissolved more iron into Wahkon Bay aquafortis for MUCH more pleasing results.  Give it a try and experiment some. 

[moleeyes36]

Unfortunately, the commercially available versions I've tried are hotter than a fire cracker and have to be neutralized after applying.  I know exactly what you mean when you say "curly charcoal", I learned the hard way by not neutralizing Wahkon Bay aqua fortis the first time I used it. 

I've thought about trying to dissolve some filings from a nail in it to see it that would "tame" it some, but I haven't tried it.

Mole Eyes

MoleEyes - I've added water and dissolved more iron into Wahkon Bay aquafortis for MUCH more pleasing results.  Give it a try and experiment some. 

Thanks, Eric, I'll give that a try.  I have about a bottle and a half on hand at the moment.

Mole Eyes

[Mad Monk]

The last time I had looked at the Wahkon Bay "Aqua Fortis" stain it was a mixture of nitric and hydrochloric acids with a bit of iron added for "color".  The idea being that the hydrochloric action on the iron will yield more red coloration in the final stain.

If you add iron to the commercial product be particular as to your source of iron.  Iron with any amount of chrome in it will give strange colors.  I tried to collect old iron nails and wire from old farms or buildings.  The idea they were made before they started to use large amounts of scrap metal in recycling into the commercial iron products.

How you treat the stain after application on the wood will have an effect on the range of colors produced on the wood.  Ferric nitrate (nitrate of iron, aqua fortis) will decompose to the iron oxide with simple exposure to air.  The relative humidity in that air will alter colors.  High humidity tends to give more yellow and orange.

When you use a carbonate caustic, such as baking soda, the fizzing action tends to lift some iron off the surface as you swab the solution onto the stained wood.  Has has a plus if you want light wood between the curl sections.  The curl is open grain and less iron will be removed from the wood.  Between the curl the grain runs almost parallel to the surface.  Stain solution penetration is far less than one  the end grain curl.  More iron will be removed from the parallel grain than the end grain.  You pick up a good bit of contrast between the sections.

Using sodium or potassium hydroxide can cause problems when you then finish the stock with an oil or oil based varnish finish.  Any strong caustic left in the wood will migrate to the surface and turn part of the finish oil to soap.

If you run the commercial stain with more iron to "exhaust" the acid you might want to try gentle heat.  Both ferric nitrate and ferric chloride are unstable above 150 degrees F.  Meaning that gentle heating will cause them to break down and convert to the desired iron oxide form,  You will get a bit of an acid smell while you gently heat.  Going to the air rather than into the wood as would be the case with heating the stock with an intense heat source.


Mad Monk

[Eric Kettenburg]

I'd pay pretty close attention to all this stuff Bill is writing.

This being said, after a whole lot of years of experience, I would say that the best af colors are obtained with stains that still have some degree acidity to them.  I've used ammonia to kill it probably as long as I've used af stains.  It's really not so much of an issue with the wood itself, worst case is it just gets darker.  The only problem really lies with lock/barrel and any other iron components in contact with the wood.  Ammonia goes a long way toward ameliorating these issues and frankly I find it to enhance the color somewhat, although I don't swamp the stock in it like I was trying to drown it in a bathtub.  ymmv....