An Aqua Fortis Question

[Rolf]

Dr. Tim, What a great idea -- must be I thought the same thing !

Rolf, Long John,
I've had vinegar/iron brewing for almost two years and have yet to achieve anything red.  I keep cutting it with vinegar and trying, but I always end up with grey (which is easy to achieve pretty much immediately with vinegar and iron mixture). 

How many coats did you but on the wood? The first two coats of my stain turns the the wood blueish grey. The next 2-3 coats changes the color to reddish brown. I think this is caused by the natural lyes in the wood neuturalizing the vingare acid. When enough acid is applied, the lyes are spent and the red iron oxides/hydrats stabile. (just my theory).

Best regards
Rolf

[bgf]

Rolf,
I tried everything from 1 to 4 coats, even straight vinegar on top (I had a similar theory).  The original solution must be diluted 32:1 at this point, but it is still darker than yours.  I recently got it to the point where it appears reddish-orange going on, but then it still dries to grey.

I think my solution is FAR too strong judging from your pictures.  I used mild steel filings (which I save in a jar) and some rusty barbed wire (I've got miles of it, too, coiled up waiting for a purpose).  I cut a test batch in half again just now, so we'll see.  I know it works, just a matter of figuring out how!  I like the idea of a completely safe, organic stain using easily obtainable stuff, so I'll keep trying.

[Long John]

b

Put a little linseed oil on that bluish gray colored wood and tel me what you get.  Remember that the percieved color is reflected light.  The diffraction caused by the surface will modify the the color spectrum of the reflected light.  The oil fills in those surface features and gives you a better basis for judging color.

My stain is just plain cider vinegar and old iron from rusty nails and barbed wire.  The stain goes back to the middle ages and every farm used vinegar to pickle and preserve vegetables, eggs, meats, etc.

Dr. Tim

As soon as you ad the nitrate you add the need to use heat to drive off the nitric acid.  Is that what you want?

Best Regards,

John Cholin

[bgf]

LJ, Thanks (you too Rolf, I meant to put that in) -- I'll try swiping with some finish later.  It might do the trick as I've noticed I get the red-orange color when the "grey" is wet (with vinegar, peroxide, etc.), but I'd been so discouraged by the grey that I didn't think to try and put the finish on anyway.  It isn't a total waste, as I really like it for base layer, just as it is.  The LMF stains I have come out too pastel/light for me, but when I put them over the top of a vinegar/iron grey base, they are much richer and darker even before finish. 

[Dr. Tim-Boone]

Dr. Tim

As soon as you ad the nitrate you add the need to use heat to drive off the nitric acid.  Is that what you want?

Best Regards,

John Cholin

Yes, I have used it with water and alcohol and use a heat gun to turn the color. I am wondering If I can get more contrast by using vinegar at the Ferric Nitrate crystals???

[cmac]

I used aqua fortis (my own mix-50/50 nirtic-water) and dissolved 3 old square nails to stain this stock. Then oiled with refined linseed oil. I've always been happy with the results of aqua fortis. Except on one stock it just wouldn't darken up. This may have been the wood or the stain?

[Long John]

The iron does not know what acid turned it into iron ions.  It doesn't care.  The advantage to using strong acids like nitric is that you can get lots of iron to dissolve.  Thus you only need one 'coat" or application of stain.  If you use a weak acid like vinegar (acetic acid) you don't get as much iron into solution, so you will need multiple "coats", but you have more opportunity to select which iron ion you want ferric for red or ferrous for black.  The inherent acidity of the wood will also play a role.

I use vinegar because I have difficulty believing that a vial of nitric acid could be shipped to a warf in London, loaded into the hold of a ship, knocked about at sea for 3 months, get off-loaded in Philadephia to a warehouse, get loaded onto a wagon and hauled over umpteen miles if dirt road to Christian Springs or Lancaster without springing a leak.  I also have difficulty believing that those old German smiths would pay for that acid when they could get the same effect for free with vinegar their wife used for pickling eggs and such.

But I am nuts and we all know it.

Best Regards,

John Cholin

[rich pierce]

Long John, I know you've covered this before but maybe you could summarize again for us.  I've encountered 2 common problems with homemade iron-acid based stains.  If you can think of other common ones, fire away.  Thanks!

1) What to do with your AQF or vinegaroon mixture if there's a muddy precipitate?

2) What to do if after application and heating, the stain is too brown without reddish undertones?

[Dphariss]

The iron does not know what acid turned it into iron ions.  It doesn't care.  The advantage to using strong acids like nitric is that you can get lots of iron to dissolve.  Thus you only need one 'coat" or application of stain.  If you use a weak acid like vinegar (acetic acid) you don't get as much iron into solution, so you will need multiple "coats", but you have more opportunity to select which iron ion you want ferric for red or ferrous for black.  The inherent acidity of the wood will also play a role.

I use vinegar because I have difficulty believing that a vial of nitric acid could be shipped to a warf in London, loaded into the hold of a ship, knocked about at sea for 3 months, get off-loaded in Philadephia to a warehouse, get loaded onto a wagon and hauled over umpteen miles if dirt road to Christian Springs or Lancaster without springing a leak.  I also have difficulty believing that those old German smiths would pay for that acid when they could get the same effect for free with vinegar their wife used for pickling eggs and such.

But I am nuts and we all know it.

Best Regards,

John Cholin

Where do the accounts from the 18th c of maple stained with nitric acid come from if they could not get the stuff?
Seems to that their not having Nitric Acid is an assumption. Accounts of the time do not agree with this.
Further I believe the use of Vinegar to make ferric nitrate stain is a modern construct I will continue to believe this until some period description of stains made in this manner is  found.

Dan

[heinz]

The magic ingredients in making nitric acid were saltpeter and vitriol.  Vitriol was made in turn from sulfur and saltpeter.  So there were no little glass bottles on the pier.  They always find a way to useful chemicals, in this case probably stone crocks, in barrels packed with clay or brick dust.

And aqua fortis does show up in 18th century shop inventories.

[Chuck Burrows]

While I don't have any references to ferric/ferrous acetate which is what you get when dissolving iron with acetic acid i.e. vinegar and not ferric nitrate(iron dissolved with nitric acid) it is not a modern construct at all - also vinegar blacking, vinegaroon, etc. it has been used for blacking leather since at least the time of the ancient romans. While I have not studied it's history for use in wood staining a quick search noted it  has been used to ebonize woods since at least the latter 1800's:
references for leather
The Circle of Mechanical Arts 1813 - in bookbinding
http://books.google.com/books?id=6_oGAAAAQAAJ&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q=vinegar&f=false

An original recipe from an 1870's harness making manual:
 VINEGAR BLACK
For giving color to the grain of leather there is no blacking that will at all compare with the well known vinegar black. This may be made in various ways. The simplest, and, without doubt, the best, is to procure shavings from an iron turner (note: some folks get the turnings from brake drums) and cover them with pure cider vinegar; heat up and set aside for a week or two, then heat again and set in a cool place for two weeks; pour off the vinegar, allow it to stand for a few days, and draw off and cork up in bottles. This will keep for a long time, and, while producing a deep black on leather, will not stain the hands.

ebonizing wood:

Popular Science News, Volume 12 - 1878
http://books.google.com/books?id=ehlbAAAAYAAJ&pg=PA88&dq=ebonize+wood+with+vinegar&hl=en&sa=X&ei=hSzRUIvGB4ee2QXSg4DYDQ&ved=0CEkQ6AEwBDgK#v=onepage&q=ebonize%20wood%20with%20vinegar&f=false

http://www.wkfinetools.com/wWorking/z_reading/1878-10-M&B-EbonizingWood/1878-10-M&B-EbonizingWood.asp

the use of logwood etc in these descriptions as a pre-wash was/is to increase the tannins in the wood to increase the darkeness when applying the vinegar black

[WadePatton]

Forgive my bloomin' ignorance, but also see Sodium Nitrate, a solid for sale-purportedly for use as per our "needs".  Would this not be another way for fellows of old to make their solutions.

Related note: with nearly all the things we now know (wrt gunshop chemistry) being called something different back then--could some things be "lost in translation"?

Thanks for the informed information guys.

[Long John]

Rich,

The sludge you are referring to is a mixture of iron oxide hydrates that have fallen out of solution.  The only part of the mixture of iron in vinegar you use is the clear solution on top.

When I look at the surviving rifles I don't see lot's of red.  Every time I go to Dixons and look at the original rifles they appear to be a mixture of dark brown and yellowish tan striping.  With a weak acid / iron stain you have some latitude in pushing the chemical equilibrium between ferrous and ferric oxides by adjusting the relative concentration of iron to acid in the solution.  This is what Rolf did.  (He took Chem 101) 

If you decant of the clear solution and dilute it with more acid you will "push" the equilibrium in favor of ferric (reddish) oxides.  If you decant the clear liquid and add more iron you will push the equilibrium in favor of the ferrous (black) iorn oxides.

Keep in mind that ferric oxide, Fe₂O₃, will absorb oxygen from the wood and air and transform to ferrosoferric oxide, Fe₃O₄, which is black.  This is the "black oxide" coating on screws and gun barrels.  I suspect the mellow brown color of the original rifles at Dixons and in the Moravian book by KRA comes from a mixture of ferric and ferrosoferric oxide.  How many nice red original rifles are there?  I don't know.  Were the original rifles stained so they would look more like European walnut?  I don't know.  I seem to remember Eric Kettenberg making posts about the use of certain organic dies.  Maybe that's where the red tones come from on those original rifles.  I don't know.

Best Regards,

John Cholin

[D. Taylor Sapergia]

Here's a picture of two Hawken rifles, both stained with ferric nitrate crystals dissolved to saturation in water.   Both stocks are of extremely hard sugar maple and obviously, have different hues.
And here's a picture of my Verner rifle, whose stock is of Western maple which is not quite so hard, and had a rather pinkish hue in the raw.

  Tho' not quite as hard, it is wonderful to work with, and takes carving very well.  It was stained with the same bottle of stain as the other two rifles.  The contemporary stocks that I see that have a reddish hue are often of red maple, which seems to come out with that reddish colour that we are looking for.  Guess I'll have to build a rifle of red maple and see what happens.

[Joe S]

Forgive my bloomin' ignorance, but also see Sodium Nitrate, a solid for sale-purportedly for use as per our "needs".  Would this not be another way for fellows of old to make their solutions.

Related note: with nearly all the things we now know (wrt gunshop chemistry) being called something different back then--could some things be "lost in translation"?

Thanks for the informed information guys.

Wade:  Since we don’t have it, it’s tough to say what has been lost, but we do have an awful lot of information on 18th century chemistry.  There is a long list of chemicals they used, with wonderful names such as spirit of hartshorn, butter of antimony or phlogisticated air.  We know what these compounds are and how they were used, clear back into the dark ages and even to biblical times.

By the end of the 1700’s practical chemistry as it related to gun building was quite sophisticated.  For example, early 1800’s British records have a dozen or so different compounds for coloring gun barrels, some of which contain several ingredients.  So, regarding this thread in particular, those folks knew very well what aqua fortis was, how it was different from aqua regia, and the various effects of these chemicals on wood and metal.

Regarding sodium nitrate – sodium nitrate can be used to make both nitric acid and gunpowder, although I believe potassium nitrate was more commonly used for these materials.

FYI:

Aqua Fortis (Literally “strong water”) = nitric acid

Aqua Regia (Literally “water of the king”) = a mixture of concentrated nitric and hydrochloric acids, so called because it would dissolve gold

Aqua Vitae (Literally “water of life) = concentrated aqueous ethanol, made by distilling wine  

I’ll drink to that.

[WadePatton]

i usually blame all phlogisticated air on the dog.  




Sorry Joe, that one was just teed up too pretty.  Thanks...and I did ask my apothecary for price/availability of some chemicals recently, and he's a shooter, but no dice, just not in his "catalog". 

much easier to find it online.