Re: Ziatype: how many coatings?

Loris Medici wrote:
> I will make my first Ziatype tests tomorrow. As Ziatype is a POP process (no
> strong chemical reaction to form the image), I assumed (maybe wrongly) that
> dmax of a single coat print may be weak (my untoned double coated Vandykes
> go only to 1.20 - 1.25...)
>
> My question is: What is your experience with Ziatype? Do you think I can get
> enough dmax with only one coating? Or should I coat twice?
>
> Will print on Whatman HP watercolor paper (don't know about the size: is it
> gelatine or aquapel?) and will use the straight formula with no additions
> (just LiPdCl and AFO).

One coat will work fine. Although a few considerations:

1) It is possible that the print may not print out completely,
especially if the relative humidity is less than needed. It is a good
idea to use a potassium oxalate (or other) solution for full development.

2) Make sure you have enough metal in your coating solution and your
sensitizer is strong enough and not spread too thin. Some of the
literature does not give strong enough formulas; feel free to check my
e-guide from link below.

3) Each paper may require differing chemistry (I have not worked much
with Whatman papers but have used enough others to always expect
differences).

4) Note that your negatives will print best if optimized for the
printing process, meaning negatives that worked best with Vandyke may
not be optimum for Pt/Pd. Even though a negative can give a good
looking print with adjustments, an optimized negative might be even better.

-- 
Jeffrey D. Mathias
http://home.att.net/~jeffrey.d.mathias/