[pure-silver] Re: KBT fog - was Re: KRST
----- 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 
=============================================================================================================
To unsubscribe from this list, go to www.freelists.org and logon to your 
account (the same e-mail address and password you set-up when you subscribed,) 
and unsubscribe from there.

Other related posts: