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My own Direct Carbon technique is an
extensive modification of the following in which I do not use Gum of any kind.
Gum dissolves far too readily in Dichromate when dipping and will just float the
pigment away before it has a chance to remain on the surface of the
gelatine. I seem to remember that in Art's process he incorporates the
sensitizer in the one coat pigment layer. This does work but obviously does not
follow the clues given by Echague.
There are many ways to skin a cat, although I would
never do that. They are far too helpful to me in keeping my blood
pressure down.
You will see there is a great similarity to
the Gum process using what appears to be a sizing coating
which seems to be an important part of the successful making of the
image in the Fresson formula.
Based on the translation of an
article in '' Arte Fotografico'' by Jose Ortiz Echague on Fresson Printing.
Around 1950
''The methods of Direct Carbon are those
are those in which the image is obtained directly on the original paper without
the necessity of being transfered once or twice onto other supports, as occurs
with carbon papers for double or single transfers.
In either process the paper is coated
with a layer of gelatine but which supports, only in the Direct
Carbon process, a layer of pigment dissolved in a mucilage, instead of being
incorporated in the same base gelatine as occurs in the Carbon Transfer
process.
Here stands out the fundamental difference
between Direct Carbon and Carbon Transfer. In the transfer method the
undissolved gelatine, more or less, makes an impermeable outer layer,
and it is then necessary to invert this to dissolve the pigment confined
beneath to make the image visible
In the direct carbon process the pigmented
layer located on the surface of the gelatine penetrates only superficially
into the interior of it, and so can be attacked from the outside without
inversion onto another support. This abrasion of the gelatine/pigment
in Direct Carbon requires a more energetic medium than just the dissolving
action of a water bath which alone would be insufficient in developing/
clearing the image.
So, to recap.The paper forDirect Carbon is
made of a thin layer which is generally gelatine; on this layer is coated
the pigment dissolved in a vehicle such as Gum Arabic, Tragacanth Gum, Lichen,
Agar-Agar etc., but the base coating is always formed of a thin layer of
gelatine in direct contact with the paper support.
The result of this way of
preparing the paper, for one thing, is the various qualities that can be
obtained according to the proportions of gelatine and gum muclage used and
also the thickness of the pigmented surface layer and the extent to which
it penetrates into the base layer when development takes
place.
The most usual commercial papers are the
brands, ''Fresson'', ''Artigue'', and ''Hochheimer''. Their manufacture is a
secret of their makers and certain of them have disappeared with their
originators.
Sensitization is by dipping the prepared
and dried paper in a 1% to 4% Pottassium Bichromate
solution.
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Enjoy, already.
John- Photographist - London -
UK
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