nitric acid stock treatment

[RichG]

working on an early Lehigh stock with incised carving. When I treated the stock with 10% nitric and heated it ,it became apparent that the acid didn't flow into carving. I tried to retreat just the incised carving and I now have a blotchy rather ugly stock. Do I re sand the entire stock and try again? I don't want to re-stain the entire stock as that will make it darker and my red varnish will darken it more. In my attempt to rub the color out I've rubbed through the stain in a couple of spots. Also their appears to be some very hard grain running the length of the forearm that doesn't want to stain. Any ideas? 

[smallpatch]

RichG,

Just reapply it, wait for it to dry, and maybe even reapply again, BEFORE you heat it. AQ is a chemical reaction, rather than a stain.  The wood will only go so dark, based on the woods chemistry.  It is rather forgiving in that respect.  Wood density will cause some variation in color.  That's how it works.  That's the beauty of the process, and the reason the figure is accented so nicely.

Good luck.

[RAT]

I had the same result the first time I used it. I had used a patch of t-shirt material to apply the stain. I sanded the stock to remove the stain and re-applied. The 2nd time I used a paint brush to get into some of the carving. I also found that placing a cotton ball inside the t-shirt scrap helped hold more stain and got into the moldings better.

I've heard various versions of why aqua fortis stains wood. The one I go with is that the acid doesn't actually stain the wood. The only reason for the acid is to dissolve the iron. Upon application the iron enters the wood and then rusts when heated. It's the rusting (oxidation) of the iron that stains the wood.

[tallbear]

Rich
A clarification of exactly what you are using to stain with might help you get proper answers.Since the term aqua-fortis was used in the period to describe both" nitric acid" and" nitrate of iron" stain there tends to be some confusion.Are you using diluted nitric acid or are you using "nitrate of iron" stain which is made by dissolving iron in nitric acid.

Mitch

[Dr. Tim-Boone]

Thank you Mitch!  I was getting really confused............. Not sure what to expect from putting a 10% solution of nitric acid on a stock.....

[Acer Saccharum]

Also, if heat just hits the high areas, the valleys will not turn color. You need radiant heat, not just hot air. I use a heat gun, others use a red-hot bar, or fire from a forge.

[RichG]

10% nitric acid. no iron dissolved in it. Produces a butterscotch brown color, no reds or dk. browns. I'll put a red varnish over the top.

[RichG]

And I was using a heat gun.

[shifty]

I use a red hot stove eye or hot plate

[tallbear]

Rich
I wish I could more help but I've never used the method you are following.I'm curious about where you got it.I wasn't aware of people using straight nitric to get a golden color.Is it possible you mistook directions to use dilute aqua-fortis stain(meaning nitrate of iron stain) to achieve the golden color rather than just dilute nitric acid. Most of my experiments have been with Nitrate of iron stain in one form or another .If you are able to rub it out that might be the way to go.

Mitch Yates

[Jim Kibler]

If it's just areas in the incised cuts that didn't stain, just darken the carving with some glaze, colored oil etc.  This will make the carving stand out a touch more as well.  Won't be any problem at all.

[T*O*F]

Stains are solutions containing pigments which color by soaking into the wood, evaporating, and leaving the pigment behind.  Chemicals are not stains, but rather reactions upon an organic material.  If you have ever gotten nitric acid, silver nitrate, or potassium permanganate on your fingers, you have experienced this reaction.  Works the same way on wood, horn, leather, etc.

Acid burns wood.  Depending on the concentrations, the chemical burn can range from light to charred.

[JDK]

So, are you saying that the 10% solution of nitric and water without iron dissolved in it may cause a chemical reaction that will that will achieve a honey color in maple....depending on the composition of the wood?

Just curious.  I, like Mitch have not tried this.  Enjoy, J.D.

[T*O*F]

So, are you saying that the 10% solution of nitric and water without iron dissolved in it may cause a chemical reaction that will that will achieve a honey color in maple....depending on the composition of the wood?

No, I didn't say that at all, you did.  I simply said acid burns wood.

A chemical reaction will, not may, occur.  Nitric acid is a strong oxidizer.  It reacts with wood just like it does with iron, but the end results are different.  The degree of concentration determines the extent of the reaction until the acid is spent.  There are many kinds of chemical burns, both acidic and alkaline.  Lye is a stong alkali and happens to produce a pleasing color when used on cherry wood.

[RichG]

no mistakes. trying to get a lehigh co. red finish on my Lehigh co gun. Joe Brooks has an article about doing this. You need a golden butterscotch color under the red varnish or the finished color is way to dark. I tried wahonka bay aqua fortis under the red varnish on a scrap and it was almost black. Aqua fortis is nitric acid without any iron dissolved in it. The modern stuff is ferric nitrate; that's my understanding anyway. At this point I'm leaning toward sanding the stock to bare wood and trying again.

[Dr. Tim-Boone]

You may be fighting an uphill battle with the acid based stains wheter Ferric Nitrate or just nitric aciid on that particlar piece of wood.... you might try some diluted Homer Danglers Golden Brown as your undercoat..sneak up on the butterscotch....

[tallbear]

Rich
I would be very interested in the Joe Brooks article if you know where I might find it.Other than being blotchy did you get the golden color you were looking for.

Mitch

[Hungry Horse]

 Has any of you used chromium trioxide to get the ambers, and honey, tones? I have, and have achieved it a couple of times. Depending on the wood, it can work. Some types of wood, for reasons I haven't discovered, don't respond well. It is pretty easy to wind up with a green tone, if your not careful.


                     Hungry Horse

[rich pierce]

@ Rich, technically you are correct that aquafortis is nitric acid w/o iron, but everyone in the business means diluted nitric acid, saturated with iron, when they say "aquafortis".  Pure nitric acid is not a great stock stain and too strong as well to handle safely.

@Hungry Horse, chromium trixoide has a nasty reputation in the business of turning stocks green over time.  There were a lot of green stocked rifles in the 70's and 80's and fewer folks use chromium trioxide anymore.

[Dphariss]

Thank you Mitch!  I was getting really confused............. Not sure what to expect from putting a 10% solution of nitric acid on a stock.....

Corroded  metal parts is one.

Dan

[Dphariss]

no mistakes. trying to get a lehigh co. red finish on my Lehigh co gun. Joe Brooks has an article about doing this. You need a golden butterscotch color under the red varnish or the finished color is way to dark. I tried wahonka bay aqua fortis under the red varnish on a scrap and it was almost black. Aqua fortis is nitric acid without any iron dissolved in it. The modern stuff is ferric nitrate; that's my understanding anyway. At this point I'm leaning toward sanding the stock to bare wood and trying again.

Ferric Nitrate will give different colors on different pieces of wood.
I suspect that nitric acid will as well.
You can get blank areas where the stain does not take. I had this with the last rifle I stained. I waited waited till morning restained, the resistant areas "took" and I then blushed it.
The stain in ferric nitrate is the iron that is solution.
It is impossible to stain a stock with ferric nitrate (which was used back in the day) and reliably get the same color of another stock stained with the same bottle of stain on the same day.
Using a stain that is not largely depleted can result in rusting of steel parts of the rifle after they are installed in the stock.

Dan

[RichG]

I got exactly the color i wanted on the first application but the surface tension in the 10% solution made it almost impossible to get it into the incised carving. When I tried to re-do the carving the surface areas around the carving turned darker than the areas without carving. Next gun the carving will be a little wider/deeper and I'll use a toothbrush or something on the carving and then swab it across the surface. I'm thinking if I sand the surface to bare wood I'll be able to see the untreated carving and treat it using a toothbrush and then swab any excess across the surface preventing any area from getting to much acid on it.

[tallbear]

Thanks for the info Rich,this gives me something else to try.Before you stained was the surface sanded or scraped? If it was sanded what was your final grit.
Thanks!!
Mitch

[James Rogers]

This has been very interesting for me. I use a 5:1 nitric without any iron and I do not neutralize.

[RichG]

Thanks for the info Rich,this gives me something else to try.Before you stained was the surface sanded or scraped? If it was sanded what was your final grit.
Thanks!!
Mitch

sanded with 320