Applying Aqua Fortis

[eagle24]

I've read all the aqua fortis posts I can find using the search function.  I'm sure the answer is here somewhere, but I can't find it.  What do you use to apply the aqua fortis (brush, rag, etc)?  Do you saturate the stock and let dry or wipe it off?  I will be making my aqua fortis from 70% Nitric Acid & 2 parts water.

[Dphariss]

First you need to deplete the acid with iron so it has a very low acidity. The acid is not the stain.
I saturate and allow to dry somewhat then recoat.
Allow to dry then heat with RADIANT heat.  I use a paint stripper gun on LOW and keep it moving. The heat must penetrate the wood as deep as the stain. I have put short stocks in the oven preheated at 150 degrees for a few minutes. I have also put stocks in the corner behind the wood stove in winter. Once fully reacted I then neutralize with warm water saturated with baking soda. All the water will dissolve.
Allow to dry.
I never rub out the stock after staining. This will result in the stock having white edges ect ect.

Dan

[eagle24]

Thanks Dan.  Yes....I will be using one of several formulas I got from various builders and dissolving iron in the mixture.

[Stophel]

Slop it on HEAVILY.  Let it sit for at least an hour.  Heat.  Do this at least twice.

[billd]

I think 1 part acid to 2 parts water is a little strong. Make sure you test it on a scrap of the same board you made the stock from. I suspect it will be very dark. I use 4 to 1 when I make it.
Bill

[ironwolf]

  I started with 70% then diluted to 6:1.  I happen to have some very old wrought iron and used fillings from that.   Let it work and age, then run through a coffee filter.  Slop it on with a shootin' patch.

  Kev

[eagle24]

I think 1 part acid to 2 parts water is a little strong. Make sure you test it on a scrap of the same board you made the stock from. I suspect it will be very dark. I use 4 to 1 when I make it.
Bill

I want it really dark on this rifle.  You may be right though, it may be strong.  I will definitely test it on a piece of scrap.  Maybe I should split the middle and go 3:1.

[longcruise]

I want it really dark on this rifle.  You may be right though, it may be strong.  I will definitely test it on a piece of scrap.  Maybe I should split the middle and go 3:1.
[/quote]

Applying stain is kinda like cutting away wood.  Once it's done it can be hard to undo.  My first use of aqua fortis ended up much darker than desired.  Might be best to go slow and gradual with the applications(s) so as to arrive at the desired destination.

[Stophel]

I think 1 part acid to 2 parts water is a little strong. Make sure you test it on a scrap of the same board you made the stock from. I suspect it will be very dark. I use 4 to 1 when I make it.
Bill

I want it really dark on this rifle.  You may be right though, it may be strong.  I will definitely test it on a piece of scrap.  Maybe I should split the middle and go 3:1.

Aqua fortis does what it does.  Adding more, or making it "stronger" will not make it darker.

The solution you use doesn't really matter (though it does have to have a certain amount of acid, or there just ain't enough for it to function).  The water evaporates away, leaving only the good stuff, so it doesn't matter how much water you start with.

Diluting it down only "stretches" your stain to make it last longer.  

I have some that's 3:1, 4:1, and 6:1.  All are exactly the same.

On sugar maple, AF tends to color lighter, and more orange-red.  On red maple, it tends to color more brown and darker.  The softer the wood, generally I have found the darker it will color...but then I avoid anything softer than the HARDEST red maple, and usually limit myself to hard sugar maple.

That said, each individual piece of wood is different, and a certain piece of wood might want to color differently than the next piece of wood of the same species, using the same staining technique.

[Dphariss]

People wanting a specific shade are better off with one of the synthetic stains.
I use ferric nitrate stain I make myself and take what comes with the individual piece of wood.
So far as I can see the actual acid level in the FINISHED stain is irrelevant except the more acid it is the more careful the neutralization must be.
I start with very strong nitric and add about 1-2 parts water. Then add steel wool or small finishing nails or some lathe cuttings I made from an old wrought iron shaft until very nearly depleted. Makes a lot of nasty brown fumes for awhile.










These were all stained with shop made stain. But I keep adding more iron to deplete it in the bottle.
The pistols are stocked in wood from the same blank.
The rifle with the moon looked awful orange after neutralizing but colored up nice once oiled.
The wood finish is made with home cooked oil in all cases.
Dan

[Dphariss]

After stain has been applied.


After heating but before neutralize.


Initial coat of oil still wet. Home cooked linseed, Grumbachers Medium III and turp.


After a few days the oil darkens a little more. Only second coat BTW. Different lighting too, heavy overcast.

[eagle24]

I wouldn't say I want a specific shade necessarily, but I want it dark.  There were a couple of rifles at the CLA show last year that were stained with aqua fortis and were very dark.  I talked to the builders about the recipe they used and that's where I came up with the ratio of nitric to water.  I don't know how this will turn out, but I will definitely try some on a test piece of maple.  I have some scraps from the same piece as the stock I will be staining.  I guess I'm going to have to get my feet wet sometime, might as well be on my first rifle.

[Dphariss]

I wouldn't say I want a specific shade necessarily, but I want it dark.  There were a couple of rifles at the CLA show last year that were stained with aqua fortis and were very dark.  I talked to the builders about the recipe they used and that's where I came up with the ratio of nitric to water.  I don't know how this will turn out, but I will definitely try some on a test piece of maple.  I have some scraps from the same piece as the stock I will be staining.  I guess I'm going to have to get my feet wet sometime, might as well be on my first rifle.

If not neutralized the stock will continue to darken over time and may turn completely black if the stain is acid.
You can get the same color, they say, by using ferric nitrate crystals in water, this has no acid at all.
The liquid is just a carrier for the iron in the ferric nitrate that does the actual staining.
I would continue to add iron, steel wool, black wire, nails, all degreased, until the reaction stops.

Dan