[pure-silver] Re: Direct toners- the Viradon mystery

A related question:  is it possible to reuse Viradon toner?  I notice that used 
Viradon acquires solid, waxy chunks of something after storage.  I've been 
filtering and reusing it, but threw it out when it started to look like orange 
juice.  Is anything lost in filtering?

Janet Ness
  ----- Original Message ----- 
  From: Richard Knoppow 
  To: pure-silver@xxxxxxxxxxxxx 
  Sent: Sunday, June 26, 2005 5:15 AM
  Subject: [pure-silver] Re: Direct toners- the Viradon mystery




  -----Original Message-----
  From: Christopher Woodhouse <chris.woodhouse@xxxxxxxxxxxx>
  Sent: Jun 26, 2005 1:56 AM
  To: "pure-silver@xxxxxxxxxxxxx" <pure-silver@xxxxxxxxxxxxx>
  Subject: [pure-silver] Direct toners- the Viradon mystery

  Until recently I have always used odorless sepia toners, normally
  indirectly, following a short bleach. Having seen some prints of Ralph's I
  thought I would try Viradon 'new' for the first time and was amazed at how
  it reacted in the wash. I know all that stuff about using a Bisulphate stop
  bath, but what I was wondering is it goes against everything I thought I
  knew about chemistry. I always thought that chemical activity goes down with
  lowered concentration. Watching through the side of my archival washer, the
  print continues to get browner and browner, changing even after 20 minutes
  gentle washing.

  I'm intrigued, what is the mechanism that allows it to continually change
  colour when the concentration must be extremely dilute? I thought for a
  laugh I would put another print into extremely dilute Viradon - nothing
  seems to happen. What am I missing? (polite responses only!)

  -- 
  Regards Chris Woodhouse


     This is a well known characteristic of Polysulfide toners. They have the 
strange property of toning faster as they are exhausted or diluted. I don't 
know the chemical mechanism. A pretty strong sodium sulfite bath (10%) acts as 
a stop bath but the print should be washed quickly especially at first.  If the 
toner is dilute enough it can result in a peach colored stain. Kodak Brown 
Toner behaves the same way.  Kodak Hypo Clearing Agent stock will work instead 
of the sulfite bath (since its buffered sulfite at about 10%) but is an 
expensive substitute. 

    How extremely dilute was the experiment?  



  --
  Richard Knoppow
  dickburk@xxxxxxxxxxxxx
  Los Angeles, CA, USA
  
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