Assayer's Test Marks

[dognose]

Hi,
When the scratch test is made, it appears to be done freehand, but in all the German spoons that I have seen, I have never seen one that has slipped off the edge, did the assayer use a special tool?,
regards Trev.


(admin edit - photo examples added - 2/23/07)
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[Bahner]

Hello, I have not seen a slip either. They simply used a hammer and one of those tools needed for engraving. The spoon was then fastened to an instrument called "Gravierkugel", a kind of ball split into two halfes, and between these halfs the spoon was stuck tightly, so the craftsman could use two hands with hammer and engraving tool to remove the silver. Hence no slip. And let's not forget - these guys were good. Best wishes, Bahner
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[dognose]

Hi Bahner,
Many thanks for your response, they certainly were very skillful,
regards Trev.
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[Hose_dk]

In my book they write that the sample was taken with a "gravstikke" and that it was done with hasty movements. They also call it tremulerstik.

The oldermandsranke (danish for the zig zag. Is wery unusual in Denmark. They used needles.
The object was scratch towards a probersten (probiren steine) next to the mark they scratch a needle - they had needles in various lod. By comparing the mark by the needle with the mark set by the object they could see what lod.

grav=dick
stikke=to cut.

That was a difficuelt description. I am not used to explain the mystery of silver in english.
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[Hose_dk]

that is hasty should rabbit

rabbit moovements
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[dognose]

Hi Hose dk,
Many thanks for the description, yes it did make sense, thanks again,
regards Trev.
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[admin]

The technique was explained to me many years ago by an old school European silver dealer. Don't know if it is right or wrong, but it sounds plausible.
He related that a special engraving tool was used. Don't know the proper silver related name for it, but in drypoint or mezzotint print engraving, it would be called a "rocker". The rocker is "walked" across the silver surface resulting in the zigzag and the raised flakes left in its wake are shaved off for assay testing.
If this is a workable method, it makes far more sense to me than someone patiently zigzagging back and forth with a straight graver or burin.

Regards, Tom

ps. just found this at ->
http://museosdevenezuela.org/Documentos ... tor2.shtml" onclick="window.open(this.href);return false;
my very limited Spanish tells me it explains the why, more than the how. But, if anyone can extract something more from it, please let us know.

BURILADA:
La "burilada" que efectuaban los oficiales del gremio de plateros denominados marcadores o contrastes, consistía en la muestra de metal que se extraía de la pieza utilizando para ello el buril. Mediante este procedimiento, era posible evaluar la pureza del metal empleado comprobando con ello su respectiva ley (de acuerdo a lo exigido en la mayoría de las ordenanzas, once dineros para la plata y veintidós quilates para el oro). La marca dejada por el buril o "burilada" es algo profunda y siempre en forma de zigzag, ella resulta asombrosamente escasa no sólo en la platería venezolana sino también en otros centros hispanoamericanos particularmente importantes (1).

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[Hose_dk]

But somehow it looks as though they used different type of tools. I cannot beliew that the skill of the asseyer is the reason for this difference. Some look as though they were made by "free hand" others that they used a tool for just to - well I dont know !
One even slipped when making.
Some are regular from beginning to end others have had a slow start or end.

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[Bahner]

Hello, this is going to be a bit long, I am afraid, but I feel some people might be interested to learn more details about this. It refers to Germany only.

Those needles that Hose_dk mentioned were also used in Germany. The method was called “Strichprobe” and the stone on which it was performed was called “Probierstein” . Either the colours of the silvery lines on the stone were simply compared, or a special combination of acids was applied so see how quickly the lines dissolved and whether there appeared bubbles during this process or not. So with this method one could also tell silver from other silvery metals. But all in all the method was not too exact. That is why the other method was used much more often.

It is called “Kupellenprobe”, the zigzag-line is most often called “Tremolierstrich”. “Tremolieren” is an oldfashioned German word for “shaking” - it looks like the person did it with a shaking hand. Sometimes one can also find the version “Tremulierstich” - “stich” referring to the fact, that silver was actually cut out of the object (“ausgestochen”). That the cut was not done in a straigt line had a reason. The technique of melting silver back then was not highly developed. The fineness of a silver piece was simply not that homogenous as it would be today. If one would cut out silver from a piece in three different places and checked the fineness, it was likely that one got three different results. In one or two places the fineness would be too low, in another place it could be much higher, but the the average of all three samples would be correct. By zigzagging one was likely to cut through the portions with the lower and higher fineness and would thus achieve a good average result, which would be close enough to the actual fineness.

The warden did not check the fineness piece by piece, he took samples from several pieces of the same maker and would melt down all those samples together. He used a small metal cup for that, called “Kupelle” or “Cupelle”. I believe it was made from iron. By applying chemicals to the melted metal he could separate the silver from the other metals and would finally weigh, after everything had cooled off, the pure silver that remained. By comparing the original weight of the samples to the weight of pure silver finally found, he could tell whether the fineness of the silver used by the maker was correct.

Then stamping it with a town mark or a warden’s mark (however it was done in that particlar city) would imply, that the silversmith would have to pay an additional fee to the warden. Many silversmiths avoided that, that is why one can often find just a number for the Lötigkeit and the Tremolierstrich. The number for the Lötigkeit was usually stamped by the maker himself before he gave it over to the warden for checking. If the fineness was found to be too low, the maker could be heavily fined (some cities had a hand or the head of the silversmith cut off ! Well - that was some time ago... Other cities settled for a huge sum of money) and the objects were destroyed and kept by the authorities to be melted down.

It looks like all to many silversmiths did nor really bother about the consequences of using “bad” (“unterlötiges”) silver. After 1900, when analytical methods had been greatly improved, more and more German affineries had to state that the majority of old silver they received for meltdown had a fineness lower than the guarantee mark would imply. Best wishes, Bahner
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[dognose]

Hi Bahner,
Thank you for an excellent explanation, I wonder sometimes why people went into the trade of the silversmith when the penalties for an error were so severe, just the minimum of losing the items sent for assay could ruin some and prison,transportation, heavy fines or even worse for larger offences, it makes it all the more amazing that we do find pseudo hallmarks and other irregularities,
regards Trev.
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[Hose_dk]

Thanks for the exelent explanation of the method. It was very interesting.
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[Doos]

Hi,

The "cupel test" is still practised today and they use lead instead of iron to wrap the silver in.
The rest is as Bahner explained.

Concerning the "tremble" pattern, if you take a graver with a sharp but flat base (like a chisel .. is that a good English word?) and rock it left to right while applying forward pressure, you get that zigzag pattern.
Nowadays most essay offices require you to hand in the item unfinished before essaying (meaning not polished and with some extra material left on it that they can cut of) and cut of the excess material to use in the cupel tests.
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[Hose_dk]

Unfinished - I know why. Once you make an item you end up by giving it a treatment with asid. That removes the copper from the top of the silver. If you test it you will get 1000 silver (surface). The pure silver gives the thing that look of shining (white) silver. A surface that you cannot create yourself (by polishing afterwards) because the silver contains copper.
So you have to cut when testing otherwise you only test the surface. Or make tests of unfinished things.

A month ago I bought a bottle of "probiersäure für silber" when I test silver plate I have to scrach to get down into the object - otherwise it turns red when it should have become brown.
I can recommend you to bye a bottle. It only took me af few test trials to master the tecknique. (at least as an amateur) I also bought a Probiersteine - but you dont realy need that one. It is much easier to test the object directly.
With the stone you scrach the object towards the stone - that leaves a sample. The sample you test with the fluid. Brown = not silver. A red colour represents silver.
The stone is only nessasary when testing gold - to determine the carat.

I tried whether I could determin 925 - 830 - 800 etc. By testin samples with marks. In theory the darker red should mean higher content of silver. I tried 5 different samples. The one that became most red was 11lødig. Even more red than 925 silver.
I took pictures for each test. To compair results. Later I learned that picture should have been taken the same amount of seconds after I put the asid towards the object - as it tends to become more dark the longer it is in contact with the object.
Another obstacle was control of the light when taking picture. It should be the same for each picture.
I will try to post the result - but letmehost is not awailable right now. So I will do so another day.
Perhaps some of you have tried the same experiment - and can give some guidelines.
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[Hose_dk]

Not silver


Sterling 925


830 silver


12 lødigt = 750


11 lødigt = 688


As you can see to identify silver is easy. Anybody can do that. Another thing is to find the proper contents of silver.
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