[pure-silver] Re: KBT fog - was Re: KRST
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Wed, 22 Aug 2007 14:54:59 -0700
----- Original Message -----
From: "Jeffrey Thorns" <puresilver@xxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Wednesday, August 22, 2007 2:43 PM
Subject: [pure-silver] Re: KBT fog - was Re: KRST
>----- Original Message ----- From: "Jeffrey Thorns"
><puresilver@xxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Wednesday, August 22, 2007 6:09 AM
Subject: [pure-silver] KBT fog - was Re: KRST
>
I found the odor of hydrogen sulfide very hard to bear
when I stupidly used
the brown toner in my darkroom. That is an outdoor
activity. It'll fog
photosensitive materials, too, so doing it in my
darkroom was dumb.
So, using KBT in a darkroom (without adequate
ventilation) could conceivably fog unexposed paper? Is
the result a general fog and loss of contrast?
I assume that the amount of KBT in the air would have to
be substantial.....
Its the Hydrogen Sulfide gas, the stuff that smells
like rotten eggs. Its a very powerful photoactive agent
and can cause fogging of sensitive materials. Use any
kind of sulfiding toner (anything that has the rotten egg
odor) away from film or paper. Also, the stuff is very
irritating even in amounts well below where its toxic so
should be used with plenty of ventillation.
Does it result in a general fog (fairly even), or is it
likely to leave density marks/areas?
I am trying to figure out what to look for, as I do all my
toning in the darkroom. (though I have an exhaust fan
immediately above the sink)
I don't know but suspect it depends on how the material
is packaged. Its a gas so it may not penetrate some packages
at all and may get into others unevenly. It does not mean
that everything in the darkroom is fogged only that its good
practice to do the toning elsewhere.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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