Carl Weese (cjweese@wtco.net)
Thu, 25 Mar 1999 13:57:03 -0500
Dick and everyone:
The trick to Zia and Platine is humidity. I figured this out mainly from
a statement by list member Tony McLean who told me that he was getting
nice Ziatypes on Platine simply by coating with rod and hanging them to
dry for half an hour in a ---here's the punchline--room with "normal
humidity, about 70% RH or so". Normal, I guess, for foggy old England.
So I cranked up my humidifiers and raised my lab's RH into the high
sixties. The sheets of Platine felt limp (I had found out last summer
that it is disaster to try to coat a sheet of platinotype that is in
this condition). The dampish paper coated very differently from what I
was used to. The coating seemed to go blotchy at first, and even foamed
up a bit (producing a starchy smell) but with patient light strokes of
the coating rod it smoothed back out again and slowly began to soak into
the paper. We're talking about easily a minute here of back-and-forth,
dozens of strokes of the rod. No damage to the paper (don't try it with
platinotype, the surface will come apart). The sheet can either be
allowed to dry naturally for half an hour, or surface-dried with cold
air for a few minutes.
This approach is giving me some of the finest Zias I've made yet, and
works beautifully at 12x20 and 7x17 as well as with smaller sheets. It's
also economical because even with dozens of strokes the amount of
solution Platine will absorb seems to be limited to 20-22 drops per 8x10
area. Dmax is as high as I've seen from any Pt/Pd process, especially if
a small amount of platinum (15% or so) is used in the Zia formula.
If the room humidity falls below 60% dmax begins to suffer. Humidifying
the sheet in a dry room and then printing does not substitute. If your
workroom *can't* be turned into a tropical rainforest, stay away from
Platine for Zia, or see if Dick's very wet coat technique works for you.
---Carl
This archive was generated by hypermail 2.0b3 on Sat Nov 06 1999 - 10:09:05