Ferric Nitrate Crystal Question

[James]

In previous posts regarding using ferric nitrate crystals to stain a stock I recall mention of something being "muddy." What exactly is meant by that? Do the stripes run together on curley wood, is the result hazy, or is the solution itself muddy? Is there a difference when using denatured alcohol or water as the solvent?   If I manage the next few days without errors(not particularly likely, given past performance    ) I will be using this method next week and would like to know what to figure on. Also, is there a need to make up the solution far in advance or is it a mix it and use it activity?
 Thank you,
  Jim

[Larry Luck]

James,

I have used ferric nitrate stain several times.  I have not experienced a "muddy" appearance.  I mixed my crystals 1:5 with water. They dissolved quickly into a tea-colored solution.  I applied with a cheap bristle brush and allowed to mostly dry and then cooked it off with a heat gun.  If you use a heat gun, watch the temperature and do not burn off your details and the fine edges of things like barrel channels.

I used two or three applications to get the dark finish I wanted.  Before and after applying a tung-oil finish.





Good luck,

Larry Luck

[D. Taylor Sapergia]

Larry you and I are getting the same colour and blah effect with this solution.  What I was looking for and disappointed in not getting, was very dark acceptance of the stain in the curl and a red undertone.  Not there.

That being said, have you checked out the fabulous pictures of Rev War rifles in the KRA's Moravian gun book...without exception, they match what we are getting.  One thing about the stain that is remarkable, is that you are hard pressed to erase it even with steel wool.  And it appears to be colour fast (not UV sensitive)

[bgf]

Larry you and I are getting the same colour and blah effect with this solution.  What I was looking for and disappointed in not getting, was very dark acceptance of the stain in the curl and a red undertone.  Not there.

That being said, have you checked out the fabulous pictures of Rev War rifles in the KRA's Moravian gun book...without exception, they match what we are getting.  One thing about the stain that is remarkable, is that you are hard pressed to erase it even with steel wool.  And it appears to be colour fast (not UV sensitive)

Taylor,
Have you played around with tinting the finish?  Contrary to my intuition, an adequately tinted finish though darker seems to make the wood look livelier (more depth and chatoyance) and the stripes darker than with stain alone.  I got the idea to try it from a Jack Brooks article on a rifle that was tinted really red, but you can get any color intensity or tone you want by adjusting tint (or adding more layers).  I tried it because no stain ever gives me exactly the color/effect I have in mind at the time and I like a backup plan that doesn't involve a complete do-over !  I'm not a Permalyn user (just never got around to it), but if you are, the LMF stains (tints) can be added directly to it, according to their directions.  Sorry if this suggestion is a waste of your time.

[Long John]

Ferric nitrate is one route to getting iron oxide into the wood.  The disadvantage to using ferric nitrate is the lack of an acid environment.  This reduces the solubility of the iron ion.  This can be partially addressed by making a more dilute solution and applying multiple "coats".  Since you are using a nitrate ion to put the iron ions into solution you will need to heat the stock to the temperature at which the nitrate evaporates off as nitric acid, HNO3.  If there is no acid in the solution that evaporation process might not achieve completeness.

The red undertones so many seek comes from the formation of ferric oxide in the wood as a result of the loss of the nitrate ion through nitric acid evaporation.  Unfortunately, ferric oxide is hydrophilic (water-loving) and often adsorbs water to become a ferric oxide hydrate.  There are about 6 hydrates of ferric oxide ranging in color from yellow to black.  The art is in controlling the relative ratios of those oxide hydrates.  NOT EASY!

Best Regards,

John Cholin

[Dr. Tim-Boone]

So John, it is often recommended to dissolve Ferric Nitrate Crystals in Alcohol. Will that adjust the mixture of Ferric Hydrates???  No water??
The MSDS on Ferric Nitrate indicates it has a Ph of about 1........... when dissolved

[JDK]

John,

Am I reading your post correctly that in order achieve the best results from a nitric acid stain you want to use it while it is still maintains some level of acidity?  For this nittic acid evaporation to take place?

Thanks J.D.

[Larry Luck]

Taylor,

The depth of the stain/finish pops in bright sunlight.  In subdued lighting, it is unremarkable.

John,

I neutralized the Fe03 with baking soda solution, which bubbled upon application.  The comments about FeO3 solution being neutral have sort of confused me.  Once the heat is applied, does an acidic condition persist?

Larry Luck

[Dphariss]

In previous posts regarding using ferric nitrate crystals to stain a stock I recall mention of something being "muddy." What exactly is meant by that? Do the stripes run together on curley wood, is the result hazy, or is the solution itself muddy? Is there a difference when using denatured alcohol or water as the solvent?   If I manage the next few days without errors(not particularly likely, given past performance    ) I will be using this method next week and would like to know what to figure on. Also, is there a need to make up the solution far in advance or is it a mix it and use it activity?
 Thank you,
  Jim

What I said was that "Ferric Nitrate"  when made by dissolving iron/steel in a Nitric Acid/Hydrochloric Acid mix (no longer ferric nitrate but a mix of ferric nitrate and ferrous chloride, I think ) would muddy the grain.
But what is REALLY produced by this process would require someone with more chemical knowledge than me.
I have learned that iron dissolved in Hydrochloric acid alone makes a green solution unless oxidized into ferric chloride.
At any rate if I prefer to use Ferric Nitrate I have made myself with Nitric Acid/water/iron. I am happier with the results having used both store bought stain and my own over the years.
The store bought stain that I have read (in a couple of places) has hydrochloric acid in the mix seems to get browner and browner over the years and the grain seems well, muddier. To me anyway.

Then


Now


This pistol is about 12-13 years old.
I do know that the store bought stain, used on curly maple with no finish added or neutralizing will turn the wood deep brown or black in a shorter period of time. I have a test piece. But I have never done the same test with home made stain so?

I tried completely depleted, near as I could tell, shop made stain and found it did not color as well as slightly acidic stain (proven by adding some acid to the "depleted"  stain then retesting). However, one of our Guild Members has used shop made stain and stain from Ferric Nitrate crystals with identical results on test strips.  So? Is a solution made with Ferric Nitrate crystals acidic? Don't know I have read that it is and that it is not.
Maybe my test of the non-acidic was flawed?

I can make stain with nitric acid and use it the same day. But I neutralize.

I would point out that my testing is hardly "scientific"  in quality.
The one thing I DO know is that if you are mixing this stuff use a face mask/goggles. Good test is a few drops of acid on a raw egg. Then think about this in your eye. Guild member did a demo of this at our 2012 Fair and I ordered a face shield shortly thereafter.

Dan

[keweenaw]

There are two things going on with these iron stains, whether you use iron dissolved in diluted nitric acid or ferric nitrate crystals dissolved in water.  One is the iron compounds formed in the wood are turning red after exposure to heat the other is getting blacks from the iron interacting with tannins in the wood.  Now maple is very low in tannins.  If you put a wet nail on a piece of oak for any length of time at all you get a deeply penetrating black stain.  The same wet nail on a piece of maple will change it almost not at all.  Since anything you put on curly maple will penetrate differentially into the grains, what I do to bump up the contrast is to wipe the stock down first with a tannic acid solution.  It doesn't take too much, about two ounces of solution will do three or four stocks, a couple of saturated cotton balls worth per stock.  The tannic acid won't change color on the wood but when you put your iron solution on over top of it you'll get a blackish gray color immediately (which can look terrible in the raw stage).   The gray will go away when you hit it with the heat gun and you'll end up with the stripes being darker than if you hadn't used the tannic acid. I think the reds also have more intensity with a bit of black mixed in.

Now you can overdo the tannic acid and end up with colors going to blacks so practice on a couple scraps.  I suppose I'm using somewhere between 1/4 and 1/2 teaspoon of dry tannic acid to two ounces of water in my solution.

Tom-

[Long John]

I love this chemistry stuff!

Dr. Tim,  wood is about 8 % water by weight after it comes out of the kiln.  That water is labile - it can mover around in the cellulose lattice.  It will contribute to the hydration of iron oxides.  It is conceivable that using alcohol can reduce the hydration of iron.  I have never experimented with this.

Dan,  I just checked the CRC Handbook and discovered that my memory was in error.  Hydrochloric acid will vaporize at temperatures that make it useful as means of ionizing iron.  The process is the same for both acids:  the acid converts iron into iron(III) ions and thus soluble.  The solution carries the iron (III) ions into the wood fibers.  The heat drives the acid off from the wood leaving behind the iron(III) ions.  Those ions combine with oxygen from the air and from the celloulose molecules to become ferric oxide.

The new pistol had lots of ferric oxide, thus reddish.  Over time some of the ferric oxide converted to ferrosoferric oxide (black) so the pistol turned more brown.  The old guns in the Moravian book by KRA have iron-based stains that are a mixture of ferric oxide and ferrosoferric oxide in chemical equilibrium.

Best Regards,

John Cholin