Tannin blacking as finish, historically correct?

[Stefflus]

I was discussing de-rusting yesterday, and learned that museums use tannin to blacken iron after derusting.

I knew about the phenomenon, but I have never heard of it as a deliberate finish. I was somewhat critical about its use if the original finish was some other kind of blueing, burned finish (tar or oil), or just scale from forging. And I made a point that it would be just as good to colour it with a alcohol soluble colorant.

 

But is tannin a historically correct finish?

[Stephen Olivo]

Interesting first time I have heard of this.  As I tan a lot I will have to throw some pieces in my bucket and see what happens.  I also have black walnut hull ground up and will have to try that as well.  Any more info would be appreciated.  Was it just painted on?  Or were the pieces soaked in it?  I will have to play around with it once winter is over with and I can get back to forging things :D

[ThomasPowers]

Well after reading about the possibility in The Sword in Anglo-Saxon England I decided to make a test and so took a spear point of pattern welded material that was polished and about a pound of very cheap black tea that I boiled for hours in a couple of quarts of water. I left the spear point overnight in the strong tea solution.

The next morning I pulled it out and it looked a furry black mess. "Well that experiment was a failure" I thought and took it over to the sink to try to wash off the "fur"---it slipped off leaving the pattern welded pattern showing in a sort of blue/purple/black colour---quite nice I thought though no topography as you would expect as it's a very *mild* acid.

I need to try it again with store bought tannic acid and see if that makes a difference.

[Chris john]

Japanese sword gaurds or tsuba have used this process for centuries

for patina

.Hi Thomas  you have to boil in the tannins.  it converts it to black oxide ,

The firearms trade also use the rust blueing process where they rust card the barrels or actions

and boil to convert to black oxide .most shot guns use this as well ,

if you put a shot gun in the caustic blueing process you end up with 2 barrels the caustic blueing eats the solder away .

 

Chris

[ThomasPowers]

Funny when I did it with my pattern welded material I did NOT have to boil to get the blue/purple/black effects on pattern welded steel. If you cut up a high tannin tree with a nail in it, (oak for example) you also see the blue/black effect with no boiling.

What were the billet alloys you used when you did this that you had to boil it?

Boiling it is used with traditional rust hot bluing to convert the oxides.

[Larry H]

The vikings used oak, the tannins turn the metal black (as Thomas stated with the nail scenario) I know this from my lineage and other descendants  close to me...but older..(imagine that ). the blackened swords didn't reflect the moonlight when coming ashore, necessary for the element of suprise

[Chris john]

Funny when I did it with my pattern welded material I did NOT have to boil to get the blue/purple/black effects on pattern welded steel. If you cut up a high tannin tree with a nail in it, (oak for example) you also see the blue/black effect with no boiling.

What were the billet alloys you used when you did this that you had to boil it?

Boiling it is used with traditional rust hot bluing to convert the oxides.

 
Nah your wrong  again Thomas hot blueing of firearms is a coustic solution around 270 from memory , not rust blueing at all 
rust blueing is cold only boiled to convert to black oxide which is used on the most expencive of firearms ,
as i said japanese tsuba have also use this process for hundreds of years same process converting rust to black oxide but they mainly use the tannings in tea.
i guess they are wrong too and your right , try boiling that fury black mess you stated you did .or  mix caustic with a few drops of nitric acid  for a  modern look you get
you get a real shiny black if you polish  before causticing .
rust blueing will always be a mattish    finish .
try .
Chris
 

[basher]

I have experimented with using boiled acorns .
i found that the results were poor compared to modern acids but i keep it in mind.

[Chris john]

 I know this from my lineage and other descendants .

Good for you mate mine come from Lief Erickson
hence my last name.
Chris

[ThomasPowers]

If you read my post; you will note that I got a proper colour WITHOUT BOILING, telling me I should have boiled it when it worked without boiling is rather useless, yes? Of course the alloys used play a big part in how you treat a billet to get the best differentiation of the pattern; what works great for one set of alloys may not work well for a different set.

[Chris john]

Hi Thomas bet it rubs of with your finger , oh yes it did rub off to reveal the pattern ,

 

yours may be like putting a blue solution out of a bottle never anygood only

good if you never touch of course , it was a rub Thomas

 

.As i said rust blueing is not hot blueing , hot blueing is a caustic solution and the item is held in the solution thats around 270 or more . untill colour is attained there is no rust to convert on the item put in the hot caustic solution shiny no rust .

 

The old black powder firearms were not boiled they were left  that colour including there damascus barrels ,

the boiling of rust was used to quicken the blackening .

 How good it was was how much it was rusted or etched and what was used as a etch  .

Chris

[ThomasPowers]

No the "FUR" rubbed off, leaving the colour well attached. (I though I stated that in my post, I try to be clear and specific); the colour on the blade has maintained itself for over 20 years now with no problems and this includes riding in a canvas sack of "examples" or just a bit short of being in a tumbler....

The original etch on the piece was hot vinegar and NaCl. The original billet was bandsaw blade (most likely L-6) and higher carbon content pallet strapping. I don't like much topography on *using* blades.

[thingmaker3]

Chris, if your's rubbed off with finger, then you may have done something differently than Thomas. Can you list the specific steps you took?

[Chris john]

Hi thingmaker3 ,never rubbed off mate it was a bit of a rub  .

Chris

[Adirondacker]

 Here in the Adirondacks in the late 1800's leather was shipped in from all over the world to be tanned. This was to be close to the hemlock forests. Lumber men would go into the woods in late spring and fell thousands and thousands of hemlocks leaving the tree still attached to the stump, then using spuds would peeled and stacked the hemlock bark to be drawn out the next winter with horses. They had to get out enough bark to last a whole year( short period to peel) . The bark was ground up to produce tanic acid used in the tanning process. As for the trees they were left to rot in the woods, when the supply was finally exhausted the tanning mills closed. As a young boy I boiled my traps in a big pot using Hemlock boughs and they turned black. Had forgotten about doing that thanks for the memory.

                                                               Adirondacker

[small potatoes]

Gentlemen, I find it very interesting, and a little spooky at times how these coincidences happen.  My wife is in the tannin business.

 

A little background is in order I suppose.  My wife and I spent almost eight years in Japan.  For the last two years my wife was studying a traditional tannin dye called kakishibu  This is the produced by fermenting the juice of unripe persimmons.

 

Traditionally, kakishibu was used as a preservative, adhesive, and waterproofing, the burnt pumpkin color of the finished product was strictly secondary.  However, there are modifiers that change the base color, and one of them is iron solutions.  Iron changes it to black, or if you hold your tongue just right, the moon is full, and a butterfly flaps in the Amazon, you sometimes get a blue black.

 

Straight kakishibu is almost pure tannin.  The liquid is viscous, and has a shelf life.  It begins gelling after a while, and will eventually go solid.  my wife has some pieces of solidified kakisibu that were skimmed off the top of a fermentation tank, they strongly resemble clinkers.

 

It is seldom used straight, but usually diluted with water before applying.  It had a large number of uses in Japan, waterproofing umbrellas and rain coats, preserving fishing nets, as an adhesive and wood preservative, and is very important in making sake.  Sake making is the major industrial use for it to day as a mater of fact, it binds with proteins and clarifies the sake.

 

In her classes and research though, my wife says she had never heard of it being used on metal in Japan,so I found Chris' comment about tsuba very interesting.  Not the biggest industry in modern Japan though, so it could be information that slipped through the cracks, (her teachers were textile artists rather than smiths) or there might have been a different source that the tsuba makers used.

 

Sorry I'm not writing very concisely, I spent all day pulling the front end of the tractor apart out in the snow and wind, so my brain is not at its best this evening, but now you have me interested in trying kakishibu on iron.

 

This is the website for my wife's business if anyone is interested in learning more about it:

 

http://kakishibui.com/

 

My wife is a better writer than I am.  If anyone has questions, I can take a stab at them, I learned quite a bit when she was studying, or she has her contact info on the website.  Anyway, more grist for the mill.

 

Cheers.    

[Frosty]

Small potatoes guy, you are another prime example of what I find delightful about this forum. It doesn't seem to matter how obscure or off the wall something is we have a resident expert!
 
Please put your general location in your header so we have an idea of where to go to visit you and your wife. My wife is a spinner and is always looking for different dies.
 
Frosty The Lucky.

[bigfootnampa]

Nice website!  I like the look of that!  

[small potatoes]

Sorry Frosty, didn't realize I hadn't put in my location, just outside Durango Colorado. 

I imagine you are accustomed to finding fleece stashed in odd corners.  My wife is a spinner also so I understand.  She is raising angora goats to feed her habit.

My stepsister is up your way in Palmer, so I hope to get up there some time for a visit.

 

Bigfootnampa, I will pass your complements on.  A friend or my wife's had to design a website for a class, and my wife needed a website, so it worked out well for everyone.

[Judson Yaggy]

Adirondaker's comments reminded me of a nugget of information from back in my timber framing days.  The old timers said that if you are going to peel a log do it in a month that doesn't end in the letter R.  I don't know why, would assume that the bark loosens up in the spring and summer so the tree can grow without splitting the bark.  My experience backs this up, if you are going to peel a softwood log in December you will have to drawknife it clean, in June a dull spud will do and some species you can practically pull the bark off with your bare hands.  

 

The highest tannin wood I've personally worked with is Red Oak.  When green if a slick or other piece of steel is left on it for as little as 10 minuets you will get a black stain on the wood and a blush of rust on the tool.