[frameconnews] Identification of photo process

[Daniel Clement <DanielClement@compuserve.com>]

Dear Mitch,

I have not heard of the tone "mezzotone" and so can't tell you what it
means.  My guess based on your description and your mention of "photograph"
is that the print is a hand-printed photogravure produced using an aquatint
grain as a base.  The printing plates could be further touched up using
engraving and mezzotint techniques.  The goal seemed to be to approach the
quality of a mezzotint, and the word "mezzotone" certainly approaches the
word "mezzotint."  

Below is a quotation from the Bamber Gascoigne's "How to Identify Prints"
referred to by Mr.  Frederick (a great book).  Mr. Gascoigne seems to
include "aquatint photogravure"  in the category of "carbon print."

Hope that this is helpful.

Dan Clement
paper conservator
Ithaca, NY, USA

"Aquatint Photogravure

An exceptionally fine aquatint grain, achieved by mechanical grinding of
the resin or asphalt, was laid on a normal copper plate.  The tonal subject
to be reproduced was turned into an positive transparency, and a sheet of
light-sensitized gelatin was exposed through this before being given a warm
rinse to produce a relief map of the image which could act as a variable
resist.  The gelatin sheet, when laid on the plate with its fine aquatint
ground, was impenetrable to the acid in the highlights of the subject,
easily penetrable in the darkest areas, and more or less penetrable to an
exactly appropriate degree in all the intervening tones.  So  a spell in
the acid bath would enable the acid to bite deeply round the aquatint
grains in the darkest areas, and progressively less deeply all the way to
the clear highlights.  Whatever the original, whether it be landscape,
portrait or painting, the plate could be printed in the usual way in the
intaglio press and would provide the normal appearance of a photograph with
the extra richness of an aquatint.

That was the theory, and for the most part it worked very well in practice
- though in the early years it was often found necessary to strengthen the
dark areas with added hand work, and the dotted lines of roulette can
frequently be found.  By the first decade  of the twentieth century, when a
large number of expensive books had at least a portrait frontispiece and
often a complete set of plates in aquatint photogravure, the technique was
entirely reliable and needed no retouching.  It was much used with a brown
ink for illustrating catalogues of paintings. Sometimes the familiar
aquatint grain can be seen through a normal glass, but often it is so fine
that only the 30X microscope will track it down.  The best place to look is
in the paler areas, where the ink marks have separated from each other but
are not yet so faint as to be indecipherable.  Plates of this type can be
found in books up to the 1930�s, and more recently artists have used
aquatint photogravure as one element of their repertoire in creating an
intaglio print."



 

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