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Cracking on gold rod


#1

Hi,

I have been shown a rod of gold, approx 18k and 6mm in diameter with surface cracking.

It is supposed to be of some age. If old I would expect it to be hammered rather than drawn - does the cracking indicate one or the other? Any suggestions gratefully received,

Many many thanks,

Jack


#2

Could have been improperly annealed before it was pulled through a draw plate. Might contain silicon in an 18kt alloy which is a no no. Could be that when annealed, it was done so without a protective coating or atmosphere and the oxides ran into the metal on the copper rich grain boundaries and on subsequent pulls, the oxidized grain boundaries pulled apart since oxides do not adhere to metal, etc…


#3

Its really immaterial how it was made.
Its only fit for remelting or refining.
Probably a mix of all sorts of gold inc scrap and low grade solder. I also wouldnt trust the 18ct statement. Needs an assay.
How long is it? and can you post pics of the rod ends? that will give a clue.
Ted.


#4

I would just remelt and test it. See if it is 18k. Gold can be reworked multiple times. Might have been a quickly cooled rod, who knows. In the end gold is gold. Do your thing with it, especially 18k which is more actual gold than other alloys, making it more malleable. SD


#5

Thanks - but my question is whether the cracking is any indication of whether it was hammered or drawn. The object is potentially of historic interest If old. Analysis of the gold provided no clue to age in terms of trace elements etc. So method of production is all we have as a guide.


#6

See my last post, if drawn and the ends havnt been cut off then draw tong marks will be seen. As requested, need pics of rod ends.
Ted.


#7

Thanks, but the ends are soldered to terminals with long overlap joins. There are apparent drawing striations - but these have been suggested to be from smoothing …

I personally suspect that rod to be drawn and thus not so old, but the owner of the object (I can’t show it all unfortunately) is convinced it is ancient… Cracking is often a sign of age (stress corrosion) but I just wondered if it can be this extensive just from lack of annealing - and if it is indicative of hammering or drawing.

A problem piece!

Thanks Jack


#8

Hi Jack,
Ive had lots of historical pieces through my w/shop over the yrs, from Nubian torques made from Austrian Maria Thereisa coins, to fine gold 3 wire twists, probably from Egypt.
also I closely follow all archealogical finds of gold and silver here in the UK and elsewhere.
So have some feeilng for old work.
I can see where your customer is coming from! if its say Sumerian gold then hes looking to make a financial killing.
Now as your not allowed to show the rest, then theres nout
else to comment.
good luck with your researches.
Ted.


#9

If the piece were made before the development of drawn wire would there be file marks or only abrasive marks? The striations in the photos look more like file marks than abrasive scratches.
Have you thought that it could have been cast? That’s not the right way to make a long rod, but the cracks suggest the maker didn’t do things in the right way.
I’m guessing this is part of a torque, armlet, or something else circular. If it is, are there more cracks around the outside circumference? The cracks shown in the photo are all latitudinal which would indicate longitudinal stress. A cast rod might develop such cracks while being bent into a circle or helix, especially if the alloy had not been well mixed in the crucible or there were impurities in the cast.


#10

Looks cast and filed. Those little cracks are indicative of a cast piece. SD


#11

Hi Jack,

This is exactly what it would look like if you rolled a 6 mm faulty ingot through the wire-making grooves on a rolling mill and then filed it round. (The grooves would make the rod squarish–nowadays it would then be brought to round by drawing through a draw plate, but if I were faking an ancient piece, I would not use a draw plate.) That type cracking could be caused by impurities in the ingot, incorrect pouring, incorrect cooling, incorrect annealing, or incorrect rolling (e.g., not rolling in the same direction on every pass).

If the cracks are so uniform and evenly distributed down the full length of the wire, it is not likely that it is from hammering. But since you are showing us just a small piece of surface, and we don’t even know what the magnification is, it is impossible to say anything even remotely definitive about the piece. I am only saying that if I did x, it would look like that–but that does not necessarily say anything about your piece…:-)…

I was at the Getty research Lab a few decades ago and was shown a piece with a large cone shape–a sort of cornucopia. They said they were trying to determine how it was made since there was no seam. I took a look at it (with the naked eye) and showed them where the seam was.… If we saw more of your piece, we might be able to be more helpful, as seeing only a tiny piece of surface can be very misleading…

Janet in Jerusalem


#12

janetb
December 2
Hi Jack,

This is exactly what it would look like if you rolled a 6 mm faulty ingot through the wire-making grooves on a rolling mill and then filed it round. (The grooves would make the rod squarish–nowadays it would then be brought to round by drawing through a draw plate, but if I were faking an ancient piece, I would not use a draw plate.) That type cracking could be caused by impurities in the ingot, incorrect pouring, incorrect cooling, incorrect annealing, or incorrect rolling (e.g., not rolling in the same direction on every pass).

If the cracks are so uniform and evenly distributed down the full length of the wire, it is not likely that it is from hammering. But since you are showing us just a small piece of surface, and we don’t even know what the magnification is, it is impossible to say anything even remotely definitive about the piece. I am only saying that if I did x, it would look like that–but that does not necessarily say anything about your piece…:-)…

I was at the Getty research Lab a few decades ago and was shown a piece with a large cone shape–a sort of cornucopia. They said they were trying to determine how it was made since there was no seam. I took a look at it (with the naked eye) and showed them where the seam was.… If we saw more of your piece, we might be able to be more helpful, as seeing only a tiny piece of surface can be very misleading…

Janet in Jerusalem

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#13

If drawing or hammering are the only options, go with hammering, and that mostly directly down on those cracks, with the spreading of the metal that results, being what opens up the cracks. You can see that the cracks are outlining the grain structure, and those grains retain the symmetry of their original shapes. Drawing would have elongated those grains. But it also compresses the metal uniformly onward from all directions so that tends to hide some of the cracking going longitudinally, which isn’t the case in your sample. If drawn, I think the bar would likely have broken catastrophically before the cracks responsible became that visible, because drawing puts tension on the metal and those cracks destroy the metals ability to withstand tensile forces. Hammering is mostly compressive, with tensile stresses being very localized. But again, I don’t think this was either drawn or hammered. It looks rolled to me because of a somewhat layered look only on the edge facing the camera, typical of what happens on those surfaces or edges of a bar or sheet that is not being compressed by the rolls. Meanwhile, the uniformity of pressure in rolling over hammering can cause cracking that looks exactly like your sample, being more severe as you move closer to the edges. If this were sheet metal, such cracking might be found on the upper and lower rolled surfaces from the edge extending in a millimeter or two, visible on the sides, if at all, mostly as vertical cracks only, superimposed on the “crushed” or layered texture on the sides. The center area of the flat surfaces might be free if cracking. That’s typical and common with rolled faulty metal. It might be seen with hammering, especially prolonged light hammering which might be closer to rolling than heavier hammer blows. I doubt you could get this type of cracking pattern with drawing. The forces on the metal (uniform compression laterally, and tensile forces and stretching longitudinally ) are just wrong for doing that.Peter Rowe


#14

Morning Janet, and Peter,
Its 6am here in the UK and ive slept on this one with the following thoughts.
Ive asked but Jack has refused to provide more pictures of this alleged antique artifact. So theres not much else one can say.
however, theres always a however caveat!, and you mentioned it Janet.
Its the word fake.
Its seems pretty obvious to me that Jack has been asked to try and authenticate this by its production , but thats just fiddling about at the edges.
The owner? may have to put his hand in his pocket and pay for a specialist assay. Not just for its gold content but to look for , for example trace metals that have only been available since the 1970’s/80’s for example Germanium found in computer gold scrap and other recently used elements…
Anyone who has studied the growth of metallurgy since ancient times, will know that even in the Egyptian old kingdom their gold quality and thus its ductility was as good as today, purely by empirical methods.
I mentioned in Rec Crafts Jewelry many yrs ago when Peter Rowe was the moderator, some sterling enameled Supposedly Art Neveau buttons that was brought to me to be checked.
The design was right so was the enamel BUT there was no hall marks , only the word sterling stamped in on their backs… That was the give away. The type face was from the 1950’s not 1890’s. They were fake.
As you have said Janet, IF you were going to make a fake youd do it properly, tho your much to professional to think of doing it.
What we need to do is to try and ask the right questions then maybe, well get a good answer, regretfully, Jack is not able to meet up with our collective wisdom on this one and his customer will have to look elsewhere.
Ted.


#15

Ted again,
some more thoughts.
Jack on his CV is based in the UK, and he may know that the Goldsmiths Co Assay office in London is the place to go to authenticate via analysis the metal content or otherwise of gold alloys. They have the ability to tell the difference between for example geogian sterling and modern sterling. In a recent case of fake boson’s whistles the proved in court they were fake using old hall marks inserted in to new metal.
So to ask the right question? where to go to get the right answer?
this artifact should go to their London assay office where they will give an accurate analysis of all the metals in this object and of course the percentage gold content as well. Its a non destructive test and wont harm it.
Theres lots of specialist tools now for authenticating for example man made diamonds to natural ones. Research De Beers work on this. On mineral analysis Xray diffraction has been around for 50 yrs as well.
Know your subject!.
You may gather that ive a passion for metallurgy and technical innovation in its use.
Ive just developed a way to join titanium(Pure) to silver or gold for ear wire pins. Works a treat.
Ted In Dorset UK
A Goldsmiths co member and mark holder.


#16

Hi,
What is this? Is there supposed to be a Reply (from Kim_Lilot1 ) to my quoted post?
Janet in Jerusalem


#17

Ted, in case you were unaware, Dr. Ogden is,… (from Amazon now)"… is the CEO of the Gemmological Association and Gem Testing Laboratory of Great Britain. He is a specialist in the historical development of jewellery and the author of, and contributor to, several books and numerous articles on jewelry history. He has lectured on the subject internationally and in 1977 founded the Society of Jewellery Historians to bring together jewelry experts and aficionados world-wide." His 1982 book, " Jewellry of the ancient world" is still considered a seminal work on the subject, going into considerable technical detail into how to determine methods used in real or counterfeit ancient jewelry. In short, he’s not a beginner at this, and is no doubt very familiar with and to the folks at goldsmiths hall… His question here was clearly a request for the detailed expert opinions on that piece of metal from folks like us, who while perhaps not experts in ancient jewelry, could be hoped to offer expert observations based on our own experiences with these processes on similar metal. That might, for example, be recognizing what the subtle differences might be in cracks formed with two related but different methods of working the metal…BIOGRAPHY, WORKS, AND


#18

Ted, I’ve been using an inexpensive (relatively) “Sparkie” fusion welder to put various findings, including titanium and niobium and stainless ear posts, on gold and silver things since those machines first came out in the mid 80s. Titanium posts actually fusion weld to silver and gold more reliably than silver or gold posts do, and they are cheaper too.

Ive just developed a way to join titanium(Pure) to silver or gold for ear wire pins. Works a treat.
Ted In Dorset UK

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#19

Hi Peter,
2 items.

  1. I did some reading on Jack so am familiar with his vocation.
  2. Also yes im aware of what we would describe here as a flash but capacitor discharge welder. I dont have one as I dont do much with ear stuff. it was just another way to do the same.
    Ted.

#20

Exactly Peter, many thanks

I’ve been working with the authentication of ancient (or supposed ancient) gold for some 40 years. Analysis etc etc is not the question here. Simply whether the particular type of pattern cracking seen here gives any pointers as to whether the rod was hammered or drawn. Everything else (as far as I can determine from analysis, microscopic examination and familiarity with the relevant style) seems OK - they only problem is these pesky striations … BTW the Amazon bit is out of date - retired from the Gemmological Association in 2013. Google will catch up one day!

Best to all

Jack