LAST EDITED ON 01-Dec-01 AT 01:40 PM (PST)
 

I would suggest testing all of the synthetic pigments (>Irgazine Orange - a new substitute >for Cadmium) thoroughly
and, if possible, not to use them at all.

Test it this way - grind some pigment with water and mix the resulted past with lime patty. Leave to sit for a long while (month?). If color changes - do not use it.

However this test is not the "ultimate test" - time is the best tester!
Here is an example from my studio:
I have about 2LB of the beautiful green - it was manufactured for fresco in 1930th, the original tin reads "Fine Fresco Pigments" - gift from a friend, former WPA artist. Guess what? this thing (gp) turns to ugly yellow almost as you mix it with lime. My explanation would be - some chemical reactions are very "slow" (read about it somewhere)- this pigment tested as perfect for fresco 70 years ago, but now formula became unstable.
So go figure!!!

Pigments you can trust:

Lime White
Cadmium Yellow, light
Yellow Ochre
Raw Sienna
Burnt Sienna
Pezzuole Red
Earth Red, red oxide
Light Red
Venitian Red
Cadmium Red
Raw Umber
Burnt Umber
Terra Verde
Malachite Green
Verdaccio
Veridian
Cobalt Green
Cobalt Blue
Ultramarine
Lapis Lasuly (cost an arm and a leg)

Glass mullers are expensive, traditionally they where substituted with small polished blocks of marble or granite. You can get those cheaply in local marble place

Ilia Anossov
http://www.truefresco.com/workshop