Re: Demachy and red chalk

[Katharine Thayer <kthayer@pacifier.com>]

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  
pigment.

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,
Katharine