What causes pitting on the old wrought iron?

[woodforge]

Hi,

I need to know a little about metallurgy because I am a tomahawk artifact authenticator so knowing everything I can about it helps me determine what was faked with accelerated corosion and what took place naturally.

I am trying to figure out what exactly causes pitting in the primitive version of wrought iron made in the 16th-19th C. (not the kind made today which is probably better quality). I have read at least a couple different reasons that conflicted with each other and the third one was using terminology that lost me completely. One reason I read was that these were tiny galvanic cells that are reacting with the slag/impurities and the other said the slag was what prevented the pitting by spreading out the corrosion to the entire surface.

Thank you,

[southernforge]

..... are reacting with the slag/impurities and the other said the slag was what prevented the pitting by spreading out the corrosion to the entire surface.

The slag contains glass. The iron rusts away until glass is revealed. The glass stops the rusting at that spot. The glass is uneven, thus resulting in the pattern of pitting you are talking about.

Wrought iron was readily available until the 1970s as bar stock. To reproduce your item, simply forge a tomahawk from old wrought iron barn hinges and bury in a pile of horse manure until it develops the pitting like the one you have.

[junker]

horse manure specifically? :blink:

[southernforge]

Well.. anything corrosive to iron. Horse manure smells a lot better than pig poop.

[woodforge]

I am not trying to make reproduction tomahawks.

"I need to know a little about metallurgy because I am a tomahawk artifact authenticator so knowing everything I can about it helps me determine what was faked with accelerated corosion and what took place naturally."

So the slag inclusions contain silicone (glass)? So following that logic would that mean that ALL pitting is caused by slag inclusions? I've seen steel pitted too and I doubt that had slag inclusions.

Actually it is the uric acid in manure that makes it rust so any other strong acid or base will do the exact same thing at different rates. So will salt water. The problem is when people do this to their "repro" tomahawks and try to fake these as authentic original 18th or 19th C. ones. Literally millions of dollars a year are lost in this way.

[ThomasPowers]

Ah extrapolating from *one* to *all* is generally not a good idea. I would suggest you read up on corrosion of wrought iron in general. (Galvanic action is an important process!)

Other things that can help "pit" is laying on a smokehouse floor on coarse salt from the flitches, condensation over long period of times, the quality of the wrought iron, large slag chunks can break up and fall out leaving a pit, smelting of wrought iron using coke rather than charcoal, (sulfur increases rusting).

If you have a local university stop by the Materials Science department and ask for some coaching from their corrosion expert. If you are near central NM I can refer you to a great guy at NM Tech!

[bigfootnampa]

If a faker is any good you will not detect his work! I have heard of local men who have work in many museums worldwide, including the Smithsonian... they are not even THAT good. Old wrought iron is all around. I have some but have passed on huge piles of it that were being sold. Actually all steel will pit as it rusts, even modern mild steel. To one familiar with the character of wrought iron there are clear differences though... the grain of the wrought iron is very different from modern steel and is exposed as the iron ages. It will be quite difficult to detect the differences between old wrought iron newly worked and then aged in an accelerated manner from old wrought iron aged more slowly... well nigh impossible. You would have to base your judgements on style, character, and provenance to be effective... of course history has proven that those things can be successfully faked or imitated too. So I have to tell you that millions are lost hiring supposed authenticators who cannot expose fakes that are even unsophisticated let alone those that are very well done! In addition the supposed profession of authenticator is riddled with dishonesty... what better person to authenticate unauthentic relics? History provides us with many examples! I personally met and viewed art with an aristocratic authenticator who had a villa in vienna and was making quite a name for himself in Boise Idaho. He later slipped up and was exposed as a faker himself! He had used his authenticator status to gather signature samples from hundreds of living and dead artists... he found these files quite useful in providing him models for forging the signatures of these artists. Your field of supposed expertise is mostly existent to provide cover for victims and fakers alike.

[MattBower]

"Pitting" is normally caused by rust bubbling up and flaking off, and AFAIK the mechanisms for rust formation, and the resulting pits, are pretty much same on wrought iron and steel.

The wood grain effect that one sees in wrought iron is caused by long, tiny slag inclusions (primarily silicon dioxide, aka silica or quartz -- not the same thing as silicone -- which is the primary ingredient of glass) in ht eiron.

[ThomasPowers]

Check for the presence of boron in the weld area. as borax is a commonly used flux nowadays that was not used then!


Hmm I wonder if cosmic ray damage would be "healed" by dislocation climb at elevated temperatures and if so could you examine slag inclusions to see how much had built up---but now we're discussing things that may cost more than the piece does!

[woodforge]

If a faker is any good you will not detect his work! I have heard of local men who have work in many museums worldwide, including the Smithsonian... they are not even THAT good. Old wrought iron is all around. I have some but have passed on huge piles of it that were being sold. Actually all steel will pit as it rusts, even modern mild steel. To one familiar with the character of wrought iron there are clear differences though... the grain of the wrought iron is very different from modern steel and is exposed as the iron ages. It will be quite difficult to detect the differences between old wrought iron newly worked and then aged in an accelerated manner from old wrought iron aged more slowly... well nigh impossible. You would have to base your judgements on style, character, and provenance to be effective... of course history has proven that those things can be successfully faked or imitated too. So I have to tell you that millions are lost hiring supposed authenticators who cannot expose fakes that are even unsophisticated let alone those that are very well done! In addition the supposed profession of authenticator is riddled with dishonesty... what better person to authenticate unauthentic relics? History provides us with many examples! I personally met and viewed art with an aristocratic authenticator who had a villa in vienna and was making quite a name for himself in Boise Idaho. He later slipped up and was exposed as a faker himself! He had used his authenticator status to gather signature samples from hundreds of living and dead artists... he found these files quite useful in providing him models for forging the signatures of these artists. Your field of supposed expertise is mostly existent to provide cover for victims and fakers alike.

Thanks for the attitude bigfoot. I'm sure you had something constructive to contribute but apparently it got lost in your rant. There is far more than iron to look at when authenticating--it is just one small piece of the puzzle. Yes there are many authenticators who should be horse-whipped for impersonating experts. Nice of you to lump me in with those. For you to claim I couldn't tell the difference is like YOU suddenly became the "expert authenticator" capable of passing judgement on all of us. Who died and put you in charge of all world knowledge? LOL You don't have a clue as to what I know about the subject and never will. Clearly you have a personal grudge against all authenticators and want to take it out on any or all of them. Thats fine. Take it somewhere else.

Frankly if this is the kind of garbage I get from a 'senior member' then this forum has become a poor substitute for what it used to be. The worst con-artist is the one that fools himself Bigfoot.
What a shame, this used to be a half way decent forum.


Mod Note: This is a only one member talking not the Forum as a whole. Also this type of reply to comments has never been a proper way to share information.

[pkrankow]

If you know the supposed age of the piece, and the location it was made, and the material it was supposed to be made from (and the different welded components) you can analyze the chemistry for the expected impurities, understanding that wrought made with charcoal will not have the same impurities as that made with coal/coke. Also the fuel of the smith can affect this, so if the fuel for the period was exclusively charcoal, you should see low to no amounts of impurities in coal. Recycling, which was very common, will muddy this for periods after coal became a common smithing fuel.

Materials also have specific chemistries for where in the world they were produced. This means that certain steels and irons were superior to other locations because of lower levels of impurities.

As far as pitting and corrosion, good luck. There is a difference between material types that is easily visible, so you can identify a piece made from incorrect material at least.

Phil

[southernforge]

........So the slag inclusions contain silicone (glass)? So following that logic would that mean that ALL pitting is caused by slag inclusions? I've seen steel pitted too and I doubt that had slag inclusions....

No! The slag/strands/globs of glass *stops* the corrosion which causes the *pattern* of pitting. The slag doesn't cause the corrosion, I said that it stops it and creates the pattern of pitting.

[Glenn]

Frankly if this is the kind of garbage I get from a 'senior member' then this forum has become a poor substitute for what it used to be. The worst con-artist is the one that fools himself Bigfoot.
What a shame, this used to be a half way decent forum.

Woodforge, The forum HAS NOT changed the guide lines from the past to now. Name calling is NOT allowed. IForgeIron was and is still about the exchange of information.

Your field of supposed expertise is mostly existent to provide cover for victims and fakers alike.

I read this as the members of YOUR FIELD of skill and expertise, which was then painted with a broad brush. I can see your point and your reaction as YOU KNOW this field better than others. To include the entire FIELD of any group, Blacksmiths, teachers, delivery people, blue collar workers, etc is not correct, as there are good and bad in each group. I did not read this as a personal attack against you personally.

May I suggest we continue this discussion and keep on topic. It is interesting and should provide some useful ideas. Many years ago I was told how to make modern steel look old. This was not to be used to fake objects, but to provide a weathered look to modern day productions. This was followed with the advice of date stamping the finished piece so it could not be later sold as an original. The advice was also given that if you were repairing a historic piece, the repair should be as close to the original as possible, and a date should be incorporated into the repair.

Once your research is completed, may I suggest you use references (your credentials as well as other references) and write an article on how an authenticator goes about authenticating a piece of history. I encourage Bigfoot and others to do the same. The articles would not compete against one another, but be two stand alone articles that we could add to the site data base for future reference.

[Frank Turley]

I've made a few pipe tomahawks. Some are OK, and a few were not so OK. I did study ones that were in museums. I have Peterson's "American Indian Tomahawks;" it is good and bears study. Milford Chandler wrote the appendix on pipe tomahawk construction. When he was a young man, he would go into the smithies and watch tomahawks being made. We are not talking here about quickly thrown together "throwing hawks" which are nothing more than funky hatchets. We are talking about exquisitiely forged pipe tomahawks which have an excellently filed false pedestal supporting the bowl and other interesting filing and finishing forms.

At one time, I was a conservator at the Museum of New Mexico History Division. I confess that I didn't know a great deal about conservation, but I was able to study lots of tomahawks, swords, pistols, and rifles. I took apart and cleaned many rifles. Since that time, I have met a few professional conservators who have had college training in their field. I'm told that European conservators all receive extensive training. Currently, a local Santa Fe conservator is working with Tom Joyce to help preserve his African ironwork collection.

Modern day professional conservators are steeped in chemistry. They must know about various forms of oxidation as it affects metals. They must know how to remove superficial rust and still leave a matte gray tone and some original texture. I can guarantee you that they don't use sanding belts. I used to clean superficial rust with a caustic soda solution and zinc crystals. When throughly rinsed and dried, I would protect the pieces with microcrystalline wax.

Having had a little experience with tomahawks, I would say that one would look at the thickness, and shape of the blade, and of course, the surface texture and color. There is quite a difference between the wide long blades often traded to Omaha, Ponca, Osage, and Pawnee tribesmen, and the smaller versions most often traded in the Midwest and East. One important thing is whether the hollow smoking stem is still attached, and can it be dated (carbon 14?). What is the decoration on the stem? If a guy took a hot file and pressed it on the wood to make a charred design, one begins to get suspicious. What is the shape of the eye?

I would suggest that an authenticator might get the same type of training as a conservator or at least work with a conservator to gain some of their sort of knowledge.

Now a little story. Harold McCracken, now deceased, was a renowned authenticator of Frederick Remington Western paintings, drawings, and sculpture, mainly paintings. A dealer friend named Bill Center asked McCracken point blank, "How in the world do you do it? How can you be sure, or are you sure?" McCracken said words to this effect, "Well Bill, I have seen probably thousands of Remington, Russell, and other artists' paintings. At the present time, when I see a painting, and I get an awful gut level feeling, I take a closer look, and I'm looking for mistakes. The kinds of mistakes are perhaps the shape of a horse's head, the wrong color for sage brush, the Indian tipis are cone shaped instead of being a little straighter in back and more sloping in front. If I don't get that sinking feeling, I still inspect the painting closely, but I feel better about it possibly being authentic."

http://www.turleyforge.com Granddaddy of Blacksmith Schools

[bigfootnampa]

Good post MR. Turley... and so true! I must say that having reviewed my first post here I regret having allowed myself to get a bit carried away and have written a PM to woodforge in apology for my excess zeal. Sometimes here in my ivory... oops... log cabin tower I tend to lose touch with the real world out there and become too smug and snappy in my viewpoints.

Nonetheless it is true that forgery is an ancient and burgeoning craft and it has a record of success that is enviable. It is NOT just poorly qualified experts who have been duped... the LONG list includes many of the world's best and those are only the ones that we know about because for whatever reason the forgers activities finally came to light. At this point in time even the historical examples and the old written documents that are used as comparison examples and to establish provenance can only be regarded as fairly accurate. The higher level forgery conspiracies have often involved people who would be called upon to "authenticate" the forgeries (in no way do I intend to include woodforge among these... or any honest authenticator). It is just a business fact that it can be easier and cheaper to hire the watchdogs than to fool them. Museums worldwide with their endowments and their competitive natures are a rich market for forgers despite their common access to first rate experts in each field. Many or, perhaps even MOST, craftspeople of considerable skill have had the experience of being asked to do work that might be resold or misrepresented in a deceptive way.

I had a friend (sadly departed now) who was fascinated with indian arrowheads and collected them. He wanted to learn to make them and his first attempts were pitiable. He persevered though and learned about such things as fire seasoning flints and cherts. Ultimately he was forced to very carefully mark and keep separate the points which he made because even HE could not otherwise sort them from his historical collection. He KNEW his originals to be such because he gathered them from the trails of the mountains personally. There are in the world TODAY the finest flint knappers (in terms of quality anyway... perhaps not for production work) who have EVER worked stone! Many, I think nearly all, seem to be ethical people... but the potential for forgery is obvious.

[woodforge]

Apparently it is not possible for the members to stay on topic Glenn. A direct answer to a direct question was all I was looking for and the closest answer I got to it is to read more about Galvanic corrosion. Yeah, I did that. I've studied Chemistry. I know how to look & studied with digital microscopes and chemistry at shapes, thickness, pipe designs, patina, wood stems, etc. etc. and all the varied parameters involved there. BTW, its not a good idea to stick somebody elses tomahawk in a gas chromatagraphy flame anaylyzer to see what it was made of. I've worked with conservators and studied thousands of originals and fakes. I don't go by gut feelings. But unfortunately I didn't ask about all that. Getting off topic seems to be all there is available here.

[fciron]

Sir,

I went back and re-read your original question to see what all the fuss has been about. It sounds as though the information you are seeking is in the third example turned up in your original research. I would suggest you inquire at you local college or university for someone in Metallurgy or Material Sciences who may be able to explain it plain English.

I might also suggest that you be less insulting to people of whom you request favors. No one here is obligated to answer your questions; this forum is a conversation which most of us participate in for fun.

[Nakedanvil - Grant Sarver]

Conversations, whether online or oral take twists and turns and go off in different directions. It's not like a professor asking a question and directing the student to stay on subject. In a peer-to-peer conversation, no one controls the direction it takes. To think otherwise is to put put yourself above the rest. Funny how some folks feel it is "their" thread and it can only go where they want it to go.

Yes, in forums, we go off on tangents, but the information you're looking for can usually be found in the chatter. Otherwise, do your own research.

[Steve Sells]

one thing about the internet: If you dont already have some idea of the answer, its hard to tell the PhD's from the 12 year olds that read and post a lot. But to complain and blame an entire site for any post is just poor judgment, You are asking advanced questions that can not really be answered fully in a net post, you had been advised to seek a local University, so that you may come to understand the full answer. You seem to have missed that point.

[thingmaker3]

Apparently it is not possible for the members to stay on topic

Getting off topic seems to be all there is available here.

You think this is bad? You should've been here back in '08 for the infamous hammer-handling thread. Speaking of hammers, I'm going to be trying to make an eye punch this weekend! Should be fun!

[Nakedanvil - Grant Sarver]

Reminds me of "Butch Cassidy and the Sundance Kid". "Well, first we need to agree on the rules...............

[fciron]

Reminds me of "Butch Cassidy and the Sundance Kid". "Well, first we need to agree on the rules...............

Careful, you're getting off subject again. :P