Metal for organ pipes

The search for a correct definition of Hoyt metal did not, up to now,
come to a solution.

A couple of contributors did suggest that Hoyt metal is a two-ply metal,
used for organ pipes.

Bill Finch is even giving a composition:

Hoyt metal: two ply, tin coated, 84% lead, 10% tin, 6% antimony.

Such a high percentage of lead for organ pipes is not impossible, but
not common. Even pure lead has been used for organ pipes. Due to its
own weight especially the bigger pipes did get shorter.  Using a thicker
sheet of metal for the pipe did work out negative.

So another way was chosen: instead of lead the pipes were made out of
tin. Since pure tin is rather difficult to handle, being weak and hairy,
it is common to add another material, such as lead, copper or antimony.

These alloys are more stable, and can be worked on better.  Adding lead
makes the alloy harder. These alloys are called "orgelmetaal".
Organ-metal? I do not know the correct translation.

This product can be bought in blocks, and is used by organ builders to
produce sheets by melting the "organ metal", and pouring it out on a
flat table, in the thickness they do want it to be for the purposed
pipe-size.

In old days an alloy of tin and lead could vary from 0% tin with
100% lead, pure lead, up to 100% tin and 0% lead. The 100% was divided
into 16 parts of 6.25%. So we did, and do, have theoretically 16
possible alloys. In fact we have 17, because the worth 19/3 also is
common (40% tin plus 60.00% lead:  19/3 times 6.25 makes 39.5933% tin,
or: 100% metal  minus 39.59444% tin gives 60.40666% of lead).

When it comes to organ pipes, most commonly used were four alloys:

     6-worthy:  37.50% tin with 62.50% lead, or 1 part tin and 2 parts
                lead.  used for pipes inside the organ

    10-worthy:  62.50% tin with 37.50% lead, or 2 parts
                tin and 1 part lead used for tongued pipes

    12-worthy:  75.00% tin with 25.00% lead, or 3 parts tin
                and 1 part lead used for tongued pipes and cheaper
                pipes in the front

    15-worthy:  93.75% tin with 6.25% lead, or 9 parts tin
                with 1 part lead used for pipes in the front

It is advised not to add antimony, when puring sheets of "orgelmetaal",
because this may make the sheet metal more brittle.

Sometimes a foil of tin was (and is) used to plate the pipes in the
front.

A lot more could be told on this subject. My main sources were the
handbook "Orgelbouwkunde" by Oosterhof and Bouman, and
"De Orgelkunst" by Peeters and Vente.

One small problem: I was unable to find any multi-ply metal,
used for organ pipes. Since metal organpipes are build by soldering
together their respective parts, this seems to be quite logical:
how to pour a sheet with two plies? And how to solder the pipe-parts
together, if made from this ply-metal?

Another remark: I think that Hoyt metal indeed is (or: was)
a zinc-based alloy, used for die casting. It turns out to be ,
that a couple of these alloys are specified in industry standards
(In Germany: DIN 1703).  However, a comment in this DIN-
standard is stating: if not following these standards,  zinc alloys
products are sold under their brand names. Like: Hoyt metal?