Because I'm such a brave and honest person I'm going to tell you that
nobody the hell knows the answers to the first part of your query. That
is, each person has his/her own bargain with the devil. Your questions in
fact outline the existential dilemmas that torment gummers & anyone who
says nay is missing half the fun. Which is to say, your questions are so
"trivial" I can hardly wait for the answers. If we get enough, we can
publish them & for once have a decent working manual for the process....
However, in the matter of your question (a) below, if you can get ahold of
a copy of Henney and Dudley, Handbook of Photography, Whittlesey House,
London, 1939, they have a very nice article by Paul Anderson which
suggests a protocol for 3 coats. Simply put as I recall, he says use less
pigment for same length of time, or more pigment for shorter time, but
the sky would not fall if you did both or neither, because, truth to
tell, much of Anderson's facts weren't. At the same time, he's such a
serious elegant expositor that you really think you know more from
reading him. This sounds facetious, but isn't really. Read Anderson
wherever you can find him, enjoy & be skeptical.
> a) do you use different pigment strength for different coatings, what order
> are they in, and how long do you expose them (relative to the exposure for
> the first coating)
> One thing I've noticed is that, in prints where some highlight details did not
> record at all after the first coating (i.e. all the pigment was washed away),
> they were much improved after the second coating, even for the same strength and
> exposure length. Now, this is strange if you look at it in terms of additive
My first thought is that some of the gelatine size washed away, as we
observe that after several coats (especially with long soaks) the paper
may need resizing. But your idea about some preliminary hardening or
traces of hardened gum is very plausible.
You don't describe your size, but I have found the usual 28 grams of
gelatine per litre of water makes too heavy a coat on some papers for
my style of printing. On those I'd use just one coat of size at 3/4
strength. Then size again at coat whatever if I had to.
Also, are you using one part gum to 2 parts dichromate? That's a more
sensitive emulsion, will fill in your highlights.
> preliminary pigmentless sensitised and exposed gum "primer" coat would improve
> single-coated prints?
>
The Pictorialists often did just that, or put in very tiny amounts of
pigment to give an overall tone. Whether this would "improve" the print
is a highly personal question, like what is art. It could be also that a
build-up of gum causes shadows to haze or curdle. In other words, the
interlocking variables alter cases...
> I guess I should try it, but I'm darkroom-less at the moment....
You don't need a real "darkroom" for gum. I coat by low
roomlight, obviously a much pleasanter way of life, and just dry paper in
the dark -- an alcove with a black felt curtain.
Good luck, hope you'll let us know how matters evolve....
Judy