> Well, I guess for 20 odd years then the prints have just been developing a bit
> more in the fix. I use rapid fix, tho, and that's pretty strong so I think
> it
> stops
> quickly enough. Never refresh chemicals, always start new.
>
Annsan,
You've been stopping your prints with water. No harm in that. Lots of
photographers I know do that as part of their usual method. I think you can
dispense with the tablespoon of vinegar, though, as it's not having any
effect.
As to whether you should replace the tray during your printing session, try
this: after you finish a session, place the tray of water aside somewhere
and let it evaporate over the next few weeks. When it's finished
evaporating, you'll be able to see fairly easily how much developer solution
has carried over into the water tray that you're using as stop.
So as not to create any gratuitous suspense, I'll just say that I think what
you find will shock you--there will prove to be lots of developer in the
stop-water which will reveal itself as a brown, oxidized layer of crud on
the bottom of the evaporated stop-bath tray.
> Please note - BE CAREFUL GLACIAL CAN BURN YOU. For a very short time in
> my life I worked in a chemistry lab at the U of Maine in Orono - that was
> horror
Glacial is pure acetic acid. Stop bath mostly comes as a 28% solution, which
is sufficiently diluted that it can't do any harm. "Indicator" stop bath has
a testing chemical called Bromocresol Purple added to it. Most photographers
start with 28%, which is the standard stop bath formula that is sold in
stores. Then you dilute it further to get to acidic solution you want--Ansel
Adams recommended 6% solution (slightly stronger than vinegar), many books
recommend 3% (slightly weaker than vinegar)--it doesn't really matter. I
only use glacial because it is cheaper and it's not polluted with that
yellow "indicator" which is useless anyway (because, by the time the
bromocresol purple changes from yellow to purple, it's been ineffective for
some time already). Many people who use glacial as a starting point first
dilute it to a 28% solution, store it that way, then dilute it further for
use. If you buy 28% solution or mix stock 28% solution, acetic acid isn't
potentially harmful to you.
What you want to end up with is a weakly acidic solution that stops the
action of the developer, mainly to protect the acidity of the fixer. To test
this, here's a simple trial. Put your fingers in the developer. It's
alkaline, like soap, so it should have a soapy, slimy feel when you rub your
fingers together. Then put your fingers into the stop bath and rub them
together again. With a fresh stop bath of sufficient acidity, the slimy feel
will go away instantly and you'll get the same "clean" feel that you do when
you wash soap off your hands. With water, it just takes a little longer for
the alkaline developer to wash off your fingers.
The "slimy feel" indicator is more accurate than bromocresol purple.
I choose my chemicals to make a safe and environmentally benign darkroom. I
don't even use selenium toner on a regular basis, since that's a pollutant
unless you live near the ocean.
--Mike
-
This message is from the Pentax-Discuss Mail List. To unsubscribe,
go to http://www.pdml.net and follow the directions. Don't forget to
visit the Pentax Users' Gallery at http://pug.komkon.org.
