499/41 scull made with composite materials

[pimpf]

Hello !

Hope this scull may be interesting to see and learn. I have never encountered or seen sculls made with composite materials like this one: front side is aluminum, revese side is in alpaca (or brass).

P.S. Alas shame about condition.

Cheers,
Alex

[pimpf]

Reverse

[bwanek1]

The material is actually quite common for metal SS cap insignia. It is known as "CupAl" for copper aluminum. It most commonly found as a layer of aluminum sandwiched between two layers of copper, which is then finished with silver/grey paint or a silver wash. Sometimes, as with this Zimmermann TK, only one layer of copper was used and the front side was left as bare aluminum.

Here is one of mine:

[Donald Abenheim]

Kontrast

The Russian piece speaks volumes, actually, as to the real fate of much of this regalia. Its presence here is a useful addendum or corrective, rather, to the crazed searched for the unissued, undamaged, &c.

[BenVK]

What bonds the layers together?

[Donald Abenheim]

Sapere aude

What bonds the layers together?

If you are able to read German, then google Cupal and be enlightened. Or Kupal, actually. Sapere aude.

[prorege1]

And a few more of the "sandwich" type Kupal skulls from my collection

[prorege1]

Reverse

[prorege1]

And a mint example

[prorege1]

Reverse of the mit example

[SScollector]

I believe heat, (and maybe some pressure), was used to stick the layers together. Many people confuse this as a plating, but it is not.
Zimmerman is the only maker that I know of, to have produced SS eagles and skulls out of CupAl that had only a copper reverse, (This was probably due to the maker having left over sheets of CupAl that were only half finished, or the two layer sheets were originally intended to be used with the copper side on the front and silver plated, as a cheaper alternative to three layers and silver on both sides).
Either way, they just used up whatever they had left, even though
there look was intended to be plain aluminum and they probably would have made these out of plain aluminum, if not for the left over CupAl sheets.

Another interesting note: For Zimmermann skulls, this particular type is the most commonly encountered and bare aluminum is the least.
In fact, aluminum 499 skulls are extremely rare.
This would of course, be due to the fact that Zimmermann didn't make
many plain aluminum skulls because of all that left over "two-layer CupAl"
which looked the same on the front and served the aluminum insignia need, just the same.

Thanks for posting the pics! It is good to see worn examples for a change.

Best, Chris

[BenVK]

If you are able to read German, then google Cupal and be enlightened. Or Kupal, actually. Sapere aude.

Unfortunately Donald, I don't speak German and I haven't been able to find the definitive answer on the web. From what I can figure out however, the friction between the copper and aluminium generated by the rapidly applied force of the die punch generates massive but short lived heat which bonds the metals together but does not melt them.

[Donald Abenheim]

Unfortunately Donald, I don't speak German and I haven't been able to find the definitive answer on the web. From what I can figure out however, the friction between the copper and aluminium generated by the rapidly applied force of the die punch generates massive but short lived heat which bonds the metals together but does not melt them.

Dear Colleague, I am no expert in metallurgy, but said sites do speak to this issue. I will leave these technical detail to others fully in the know and apologize that I do not have the time to translate all of this material. Kupal, however, I believe was and is a normal Werkstoff of the jewelry trade, as is Buntmetall.

[BenVK]

Found the answer, dead simple really..

The different layers of aluminium and copper sheet were fed into very heavy steel rollers which compressed them into a single composite sheet.

For some reason, this was really bugging me and I had to find out.