>I hope none of my students are on this list because I'm going to mention
>that they can, from time to time, be pretty ditzy.That probably surprises
>you, but I have a reason for mentioning it: I've never seen them have a
>problem with unevenness or anything else coating Van Dyke Brown. In my
>experience, coating kallitype is quite similar to coating VDB. In other
>words I was surprised when you indicated that your beginners had problems,
>leading to the use of Ilfatol.
Dick sticks in his 2 cents worth:
I tend to agree with Judy, that is, up to a point. Evenness of coating is
usually not an issue, but there is this pursuit of the "Holy Grail of
Dmax", especially with platinum and palladium. It seems everyone wants
there prints to look like Kodak Elite. If you coat too heavy, in pursuit of
the HGOD, then coating problems arise. Mottling is one of them, I see it
all the time in beginners prints and even in advance workers prints as well.
Ziatype and the Ware platinum processes are especially prone to this
problem due to the printing out function which is self masking. The masking
by its nature makes the coating thin and any wash-off of surface black only
reveals the white paper underneath. Even with the traditional developing
out platinum, the yellow of the ferric oxalate prevents a very deep
exposure of the emulsion. Again any wash off reveals the paper base.
This disease can affect any of the iron salt emulsions. If you are pursuing
the HGOD, the most desirable coating is one that is rich, heavy, not too
deep in the paper, but not on the surface, and just at the very top with no
glazing.
While I am on this topic of paper surfaces I'd like to give my theory of
one type of grain that affects some kinds of prints. I call it fiber grain
and it occurs in printing system where there is solarization. I've examined
prints under a microscope and often see grain that is like white lines. My
theory of what is happening is this. During coating the brush scrapes the
surface of the paper and raises up paper fibers. Raised fibers may also
occur naturally in some papers. Visualize some fibers is sticking up like
miniature telephone poles, and assume some degree of transparency. The
result is light during exposure strikes the emulsion on these fibers from
all directions, including from the opposite side of the fibers. The
consequence is that the emulsion on these fibers gets far more exposure
than those fibers laying flat. The result is that they then solarize and in
effect, revert back to white. This will happen mostly in the dark areas of
the print.
Dick Sullivan