"Tony Spadaro" wrote


Have you actually seen any vibrant autochromes? I ask because the ones
I've seen look pretty pastel to me.

They have faded. It is the use of organic dyes I imagine. Any organic
dye will fall prey to oxygen and UV given enough time.

Metallic colorants are quite stable, silver for instance. If metal
salts were used for coloring an Autochrome's starch grains then
the colors should last a long time.

Red ochre (rust), calcium white (chalk) and bone black (burnt bone)
have demonstrated lifetimes greater than 10,000 years. Not in the
slightest affected by UV.

I remember having Prussian blue (Iron cyanide), cadmium orange (cadmium
sulfide), cerulean blue (cobalt/tin), cobalt green (cobalt/zinc)
and a whole host of others in a paint set when I was young.

The old stable pigments were still available from Russian art supply
houses last time I looked. Or you can scrape them off the floor at a
metal plating plant.

If you want stable ink-jet colors, I am afraid EPA America may not be
the place to find them.

--
Nicholas O. Lindan, Cleveland, Ohio
Consulting Engineer: Electronics; Informatics; Photonics.