10% nitric acid

[A.Merrill]

    A friend of mine came to me with a half gallon jug of nitric acid he got from a chemist. The label says its 10% nitric acid. Is this strong enough to make stain with?    AL

[greybeard]

Try it on a scrap of maple and you should have the answer.  Perhaps twice???
Bob

[Dphariss]

The acid is not the stain. If it will dissolve sufficient iron it will work as a stain. 10% should work OK as is.
 Be careful!.
Wear protective gloves and face protection. Nice to have a 5 gallon bucket of clean water handy for washing just in case.
Do this outside, nasty fumes are generated.

Using a stoneware container, though I suspect Pyrex will work OK too. I use a pitcher, put in about a cup or two of the acid then add a small quantity of degreased steel wool 1/4 pad maybe or some smallest finishing nails. STEP BACK immediately.
When the reaction in mostly over add more iron until it will dissolve no more and no apparent reaction is taking place. No bubbling or other signs of its acting on the iron.
Allow to cool, probably over night is best, then decant into a lidded jar or bottle. There may be unreacted steel in the bottom this can be discarded there may be sludge in the bottom as well. Add one small nail or other small bit of iron to the decanted stain and see if it shows any action or leave overnight. If its gone add another. Its likely there will be sludge in the bottom of the jar in a day or two. I just dip a cloth in the stain and not stir this up.
Now apply it to wood pretty heavily then allow to dry then heat with careful radiant heat till full color develops. Wood needs to be pretty hot 150-180 degrees. Radiant heat, electric stove burner, paint stripper gun on LOW will work. Back in the day they would heat a steel bar in the forge and pass it over the wood allowing the heat to radiate into the surface.
DON'T OVER HEAT or scorch the surface.
Use a backing soda wash, baking soda dissolved in warm water, to neutralize. If it bubbles the stain is still plenty acid but if the color is good leave it alone or add a little more iron
Above all wear safety gear and BE CAREFUL handing the acid. Acid is dangerous. Strong acid can be reduced, and should be for stain making, by adding acid to an equal volume of water. NEVER add water to acid.
http://antoine.frostburg.edu/chem/senese/101/safety/faq/always-add-acid.shtml

I have 70 nitric and even cut 50-50 with distilled water its really aggressive.


Dan

[smart dog]

Hi Al,
I think 10% solution should be fine.  Dan is correct about how to turn it into a stain.  However, before you do that, try painting just the acid on some curly maple and let dry.  Heat the wood as for the stain until it turns a pink or orangy color. Neutralize the acid with a solution of water and baking soda.  Then put a darker brown stain like the LMF stains or or one of the leather dyes on top.  You may like the result.  The plain acid gives beautiful red undertones that are very deep, lustrous, and distinct from the other stain.  The effect is polychromatic, which is my preference and the reason I don't care for aqua fortis.

dave 

[A.Merrill]

    Thanks for the info guys. I just didn't know if 10% acid would dissolve enough metal to make the stain.
    Smart dog, have you ever put the plain acid on first and then aqua fortis on top of that? I wonder how that would look?
    I would like to get a dark brown with red and gold under tones.
             THANKS again    AL

[camerl2009]

id buy some stain before i ever use iron oxide thats what your basically making all you need to do is filter it mix it with aluminum powder and you got thermite no thanks oh a that sludge on the bottom is iron oxide  id keep heat away from it trust me on that one

id keep the acid for etching damascus  

[Bill of the 45th]

Cam, first your chemistry is off, iron oxide is rust, what is being made is ferric nitrate, and if you were to mix it with aluminum powder you wouldn't get thermite.  Last this formula has been used safely for over three hundred years, both as a stain, and a browning agent.  It is one of the more historically correct ways of staining long rifles, along with vinegar stain, and asphaltum, and tobacco/ammonia stain.

Bill