U of S | Mailing List Archive | alt-photo-process-l | Re: Demachy and red chalk

Re: Demachy and red chalk

On May 22, 2009, at 3:45 PM, Henry Rattle wrote:

Recent discussion of Michallet paper prompted me to get a facsimile
copy of Maskell and Demachy’s “Photo-Aquatint” paper. They
recommend a number of pigments for gum printing, Most of the
colours/pigments they mention are familiar, but second on their
list of the most suitable, after venetian red, comes red chalk. I
looked this up on the Web, but only found such things as red chalk
drawings by (e.g.) da Vinci.

Does anyone know anything about red chalk? Hilary Page doesn’t seem
to mention it in her lists of proprietary watercolours, nor is it
in Cornelissen’s catalogue of pigments.
Henry, red chalk was a red iron oxide (sometimes also called red
ochre) embedded in clay, which made it easy to form into sticks
(chalk) for drawing pretty much right out of the ground, and was also
used as a pigment by some paint manufacturers and called "red chalk"
rather than "red oxide" because of the added clay. This isn't
really too strange, as chalk extenders aren't an unusual additive to
paints, though in this case the clay is a natural component of the
mined pigment rather than something added to the paint to make the
pigment stretch farther. The clay gave a chalky, opaque, solid
quality to the paint that I'm not entirely sure can be closely
replicated by the substitutes available today. No commonly
available paint brand offers this "red chalk" as a pigment.

Henk's paint sounds like it may be the real thing (and from my memory
of the picture(s?) he posted using it, I am inclined to believe) but
my experiments with various red oxide paints (Venetian red, English
red, red ochre, Indian red, whatever you want to call it) and gum
haven't achieved quite the same effect. You need to look for
something that's as opaque as possible and a deep brick red color.
Unfortunately you can't go by the color name, as paints named
Venetian red range from an almost Mars Violet color through a brick
red to a dull orange-red, and same with paints named Indian red.
Daniel Smith's Venetian Red looks fairly close to the right hue in
the catalog swatch, and is quite opaque, my experiments with it
haven't given quite the brick red chalky look I was hoping for, as
Henk got in his prints with the "red chalk" paint; even in a fairly
heavily pigmented mix the closest I could get was a kind of orange
red, not a deep brick red. And English Red Earth, which I thought
might be another good possibility, turned out to be weaker and paler;
it's opaque but it doesn't have the strength or the saturation of
color that you'd want for this effect. The problem with iron oxide
paints (all earth colors, actually, is that they tend to be weak
pigments and to require a great lot of pigment to achieve any kind of
color saturation.

As to Mars, in a pigment name Mars means that it's an iron oxide

Very few if any paint manufacturers use natural iron oxide pigments
mined from the earth any more; they're generally made synthetically
now. PR 101, which is the pigment for all the venetian red, red
oxide, red earth, red ochre, indian red, and such-named paints, is a
manufactured rather than mined pigment. So Judy's caution that color
can change from mine to mine is somewhat outdated, but the general
caution still holds that PR 101 (red iron oxide) pigments can come in
different shades of red and orange, and in varying degrees of
transparency as well.

I think Ken may have had the right idea; since red Conte is indeed
red iron oxide in clay, maybe what we should do, if like me you don't
find a paint that will quite replicate the effect, is to get a mortar
and pestle and a stick of red Conte, and start grinding. The other
place I'd look is in companies that have a large inventory of dry
pigments, like Kremer maybe.

Hope any of this is useful,