Hamburg Silver Purity and Alloying elements

[robertmarley]

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I found several pieces of Hamburg silver marked as pictured with makers, assayers and concession mark. One of the pieces was damaged and being curious, I tested it with nitric acid. It showed a very strong blue reaction on the interior and much less of a blue reaction on the surface, results typical of silver alloys of a purity of less than 75% which is what Hamburg silver purports to be. My questions for anyone that is familiar with silver manufacturing techniques of this period in Hamburg are:

Is it possible that Hamburg silver during this time period was alloyed with copper to a degree that would give a stong blue reaction to nitric acid while still comprising 75% silver content?

More generally, in the hand making process would planishing or hammering result in a higher concentration of silver at the surface? I know that annealing draws alloying elements to the surface, I can’t remember from my materials science courses if work hardening would drive alloying elements away from the surface. Anybody up on their dislocation theory?
It also seems unlikely that they would electroplate lower purity silver with higher if electroplating was readily available at that time and place at all?

What exactly was the assaying process at this time in Hamburg? Was it very strict and thorough as in England, or are there more examples in Hamburg (or elsewhere in Germany) of silversmiths or silver making firms getting away with selling less than standard silver that still bore guild assay marks? (I hope not to precipitate a nationalist debate with this question)

I am familiar with antique silver generally and the family history of this set, I am as certain as I can be that the set is as it appears to be, that is, Hamburg silver made by the firm of Bramfeld and Gutruf, assayed by Johan Jacob Probst sometime between 1853 and 1865 . I just don't understand why I am getting the testing results that I am getting and have no easy way to do a proper assay myself.

Thank you for any help

[Theoderich]

there is a little abstract of an article about Hamburg silver fineness from silverport:

Since 1760 'Hamburg Proof' must be 12 Lot (.750); contrary to an
Imperial edict from 1667 of 13 Lot (.8125).

1845 and 1847 the Guild report to towns control administration an
actual 'Standard' of 11 Lot 12 Gran (.729) of 'Hamburg Proof'. This
fineness is in use until 31 Dec. 1887; with marked exceptions, like
e.g. a coffeepot made by »B & G« during the period of 11 June 1857 - 7
Nov. 1864 in a signed fineness of 14 Lot.

In Hamburg was the rule that the work which should be assayed, should
be shown only after being boiled white.

Letter D: 10 Dec. 1853 - 1865 period of Assay master Johan Jacob Probst

1842 Gutruf start to work by Brahmfeld as commercial, whole seller and
diamond importer; 25 May 1850 Gutruf buy a master-workshop; 26. Dec.
1852 died Brahmfeld, since then it's mentioned as 'Brahmfeld &
Gutruf'. Gutruf takes over the whole in 1855 from Brahmfeld' widow.

Concession '20': Concessionary is since 26 May 1827 Hermann Anton
Buchwaldt; he dies on 9 Aug. 1859.

Source: Schliemann, 'Die Goldschmiede Hamburgs' - ISBN 3-88771-005-3

Metallurgy is a very real science! Since centuries there are already
published tons of literatures on metallurgical problems, their
possible solutions; and on their assay methods too. Alloy's they don't
know to be Nationalist.

[AllSeasons]

there is a little abstract of an article about Hamburg silver fineness from silverport:

Since 1760 'Hamburg Proof' must be 12 Lot (.750); contrary to an
Imperial edict from 1667 of 13 Lot (.8125).

1845 and 1847 the Guild report to towns control administration an
actual 'Standard' of 11 Lot 12 Gran (.729) of 'Hamburg Proof'. This
fineness is in use until 31 Dec. 1887; with marked exceptions, like
e.g. a coffeepot made by »B & G« during the period of 11 June 1857 - 7
Nov. 1864 in a signed fineness of 14 Lot.

In Hamburg was the rule that the work which should be assayed, should
be shown only after being boiled white.

Letter D: 10 Dec. 1853 - 1865 period of Assay master Johan Jacob Probst

1842 Gutruf start to work by Brahmfeld as commercial, whole seller and
diamond importer; 25 May 1850 Gutruf buy a master-workshop; 26. Dec.
1852 died Brahmfeld, since then it's mentioned as 'Brahmfeld &
Gutruf'. Gutruf takes over the whole in 1855 from Brahmfeld' widow.

Concession '20': Concessionary is since 26 May 1827 Hermann Anton
Buchwaldt; he dies on 9 Aug. 1859.

Source: Schliemann, 'Die Goldschmiede Hamburgs' - ISBN 3-88771-005-3

Metallurgy is a very real science! Since centuries there are already
published tons of literatures on metallurgical problems, their
possible solutions; and on their assay methods too. Alloy's they don't
know to be Nationalist.

Sorry, I realize that I'm bumping up a super old thread. But is there a more definitive definition of Hamburg silver purity?

More specifically, can I assume that Friedrich Peters, active from 1841-1877, used 729 silver?

[oel]

Yes, during different time periods minimum 729 or higher.

Peter

[AllSeasons]

Yes, during different time periods minimum 729 or higher.

Peter

Great, thank you!