RE: Determining SPT with gum Was: Gums a la Demachy and Puyo

Thanks Christina. BTW, I tried srpaying with Schmincke Graphite pigment and
it didn't give good results (kind of flaky). But I liked the method and I
definitely plan to use it with other pigments...

What do you think about the method I decribed (for iron processes)? Do you
find it overkill? All I can say is that since I'm doing that way, my results
marginally improved + the exposure times are shorter...

Regards,
Loris.

-----Original Message-----
From: Christina Z. Anderson [mailto:zphoto@montana.net]
Sent: 12 Temmuz 2006 Çarşamba 17:34
To: alt-photo-process-l@usask.ca
Subject: Re: Determining SPT with gum Was: Gums a la Demachy and Puyo

BTW, to all: How do you determine your standard printing time with gum?

Loris,
If you go to:
http://www.czaphotography.com/show.php?what=learning&which=1

on my website and scroll down a tad, you will see images related to this
question.

David is totally right in that gum is not like the others in choosing SPT,
because if you think about it, when exposing, let's say, pt/pd, you look for
max black in Step 1, but the paper absorbs the chemistry, it doesn't get
thicker like gum does. So what I did was quite arbitrary, and was to choose
a time that allowed complete development in 1 hour just letting the print
sit there, but also produced a nice punchy colored layer. The layer is
stable, does not whoosh off, and allows spray development if I want to
shorten the development time to 1/2 hour (spraying after a 5 or 10 minute
soak). Once I chose this arbitrary time (UVBL 6mn, under 15 watt bulbs)
then I printed my 101 step palette and derived my curve from this.

But as they all say, YRMV, as this time with an offlist person did not work.

The other thing, tho--if you vary 6 minutes by a minute, that is only a
quarter of a stop exposure different in photographic terms, so it is not
like you have to be worried about seconds!
Chris
Received on 07/12/06-01:46:44 PM Z