Re: Hermathena and Cicero

On 1 May 2010, at 00:39, Deborah Taylor-Pearce wrote:
> Also, I have a question of my own which perhaps you (or other Café
> denizens) can answer: a letter from Pope Julius III in 1555 gave
> Bocchi and his heirs a 15-year license for printing and selling his
> _Symbolicae Quaestiones_,
>
> 	"along with the pope's promise of two hundred golden ducats
> 	from Apostolic coffers and words of praise for the book ...
> 	'with its very beautiful bronze engravings,  .....  '".
>
> Presumably, the pope was correct in his description of the book's
> "bronze engravings", in which case, why do historians studying
> Bocchi's graphic art continue to discuss "... the cutting of all the
> copperplates"?
>
> Is copperplate a catch-all term for any kind of metal engraving for
> the print trade?

Ah, I would not leap to the same conclusion of papal infallibility.
I think he was mistaken, and the artist had followed the standard
practice of his day in engraving onto plates of polished copper.

The very characteristics which made bronze preferred over
copper for weapons -- its hard, brittle character once it is cast --
would be quite a liability both when when trying to beat or roll out
a malleable flat plate for engraving, and then when trying to cut a
uniform line on the surface of that plate.

Precisely what one means by "bronze" is disputable, because
the word bronze is used to describe many alloys of copper:
the earliest bronzes were of copper with arsenic, tin is the alloying
metal in classical bronze, and there are also modern bronzes
where copper is blended with aluminium, silicon or phosphor.

In this period there was a frequent confusion in the use of the two
terms "bronze" and "brass" (e.g. King James Bible), and there is
the slight possibility that the plates could have been of brass, in
which copper is alloyed with zinc (calamine). Brass is even more
malleable than copper pure, which is why it could be used for
musical instruments, cartridge cases etc. One could certainly
have engraved onto brass plates, and in the 16th C and after
there started especially in the Low Countries and E. England,
the practice of engraving memorial brass plates, which could
then be let flush into the floor of the church without interfering
with anyone's movement. There are about 4,000 of these in
various English churches.

One can get a kind of print-like impression from a monumental
engraved brass plate, but as far as I know this is always done
by making a "brass rubbing": placing a sheet of paper over the
brass, and rubbing on the upper surface of the paper with a wax
crayon, charcoal etc. However I have never heard of brass plates
being used as an image carrier for intaglio printing, and I wonder
if the polished copper surface has superior qualities for retaining
an even layer of printing ink.

I think printmakers would be quite precise in their language: a
copper engraving is an engraving on copper. A later development
was engraving on steel, which could survive orders of magnitude
more impressions in the press, and has long been used for the
printing of banknotes and other securities, often with those
machine-engraved guilloché patterns. Modern rotary gravure
press cylinders and prepared using numerical-controlled graving
machines like the Helioklischograf, on steel cylinders with half a
millimetre of copper surface plated on, and a few nanometres of
chrome on top of that.

Incidentally the Wikipedia article on brass rubbing explains that
"brass rubbing is not the same as frottage".  I am sure Julius III
would have been much relieved by that... er... I mean, he would
be happy to know that this is the case, especially if taking place
in churches.

Conrad




___________________________________________________________________

Use the following address to post a message to all subscribers: 
 [email protected]

To subscribe, unsubscribe or change your options, visit:
 http://list.InformationDesign.org/mailman/listinfo/infodesign-cafe

For all Information Design matters:
 http://InformationDesign.org

Problems? Write to:
 [email protected]
___________________________________________________________________