[alt-photo] Re: pigment problem

[Julian Smart]

So I have now done a coat of Indanthrone PB60 on two seperate prints and 
found no problems whatsoever. I used a diluted pot. dichromate solution 
(6.5%) and gave my usual shadow exposure of 3 mins dead.  The pigment gave 
me a very nice split that I had been after, but curiously the prints  were 
effectively overexposed (enough that I could brush away the coating at will 
without destroying what I thought would be a very delicate layer).

I am now of the opinion that the W+N Indigo paint I am using has a binder 
made from a gum that would effectively print much slower if I were using it 
for my main emulsion. The paint does seem to be slightly more sloppy than 
that from most other tubes, and I can't really imagine that the binder will 
have that much of an effect when mixed with my normal gum but I think I can 
now rule out paper sizing as an issue.

I will record that I now have two very nice gumprints, both with the colour 
split I required but am still somewhat puzzled by the behaviour of the 
Indigo paint I originally tried.

Julian.