Re: Rosinotypes without Rosin ?

[Alberto Novo <alt_list@albertonovo.it>]

> Could you  please remind us why it was that Rodolfo Namias 
> decided to mix rosin with pigments rather than simply using just pigments. 
>                 Something to do with stabilizing the powder in the 
> gelatine?
> Using fixed out bromide paper, washed, dried and sensitized I have used 
> only pigment powders brushed onto the swollen matrix with some success.
Pure pigments perhaps may work on photographic paper, but if you use them 
directly on gelatine you obtain a muddy print. The rosin (but nowadays we 
might use any other more modern hydrophobic substance) helps to 
differentiate the sticking of the powder to the (more) wet areas, where the 
gelatine has not been hardened by light+dichromate, and the (less) wet areas 
where the gelatine has been hardened. Rosin is simply one among the cheaper 
substances you can use. 
Namias wrote that he had his idea because, working on a bromoil with an ink 
made too stiffen with rosin and pigment, he obtained a reversed image. In 
fact, this is also the matter of his patent. 
Alberto