< It is the negative that is the sine qua non of a good platinum/palladium
print.>
How right he is. But the biggest disadvantage of conventional negatives is their
s-shaped curve, that makes the shadows in a platinum print even flatter than
they are anyway. Even if you manage to get a (rather) straight curve, the
problem exists. In a carbon print it's a bit better because of the straight
dichromate curve.
Almost 100 years ago, Heinrich Kuehn explained, that a reversed s-shape with
contrasty shadows, flat midtones lying a little higher than normal and contrasty
highlights would be the thing to aim for. He said that we are overlooking the
midtones anyway but usually concentrate on the brilliancy in the shadows and
highlights. If you ever saw his late oil transfer prints from the 40s with their
glowing light, you will understand him. With multiple gum and multiple oil
transfer he could achieve that goal in the positive. For other, straight
printing processes, he tried printing with two negs (one for the shadows, one
for the highlights) and even developed a *syngraphic* emulsion that was produced
by Perutz and consisted of a double coated plate or film with different speed
and contrast in each layer.
This reversed s-curve is sometimes used in the graphic arts industry when
scanning for offset printing on matt paper. But has anybody on the list tried to
get the reversed s-curve in photography? I must confess that I did not yet,
because I expect a lot of trouble during negative preparation and can't pay for
digitally manipulated negs. But nevertheless I consider this to be an important
esthetic question, which to my knowledge, is neglected too often.
Klaus Pollmeier