>I used type 55 very early in my photo carreer, so I'll have to do a little
>guessing here. In general, it didn't give me enought contrast for
>alt-process printing. Most alt-process methods require a negative with
>much greater contrast range than silver gelatin. Extending the development
>time in the package didn't seem to help much.
Much to our surprise, we have discovered that the Ziatype palladium process
can be boosted in contrast to allow printing of "normal" negatives, for
instance, those suitable for contact printing on No. 2 paper. There is no
appreciable increase in grain as there is with the traditional developing
out method. Contrast can be increased by adding 1 or more drops of 20%
ammonium dichromate to emulsion to cover a 5x7 or 8x10. You could use
either sodium or potassium dichromate as well but you may not get a 20%
mixture, just use more drops of whatever concentration you can get.
Dick Sullivan