[pure-silver] Re: PMK

  • From: Bogdan Karasek <bkarasek@xxxxxxxxxxxx>
  • To: pure-silver@xxxxxxxxxxxxx
  • Date: Fri, 28 Apr 2006 11:23:05 -0400

Hi,

Just want to correct a common mis-perception about fixer. Fixer is a solution. The liter fixer solution itself may be heavier than a liter of distilled water but if you add water to the fixer solution and mix, you are merely diluting the fixer solution. The fixer will not sink to the bottom, it will only become more dilute, and the more water you add, the more dilute the solution becomes until eventually the chemicals that comprise the fixer become so diluted as to be nonexistent. Add sugar to water and you get a sweet tasting solution; add more water, and the sweet solution will not sink to the bottom, it will only be less sweet and so on and so forth, until eventually it doesn't taste sweet anymore, but the sugar will never sink to the bottom because it is not a mixture.

Agitation has nothing to do with it.

What you are thinking of is a mixture of say, oil and water. You cannot make a solution with that because the oil will not never dissolve in water. Mix them together and let them stand and you will see that they soon separate, oil forming at the bottom and water at the top. That is not the case with fixer. If it were true, there would be separation which as you can observe, does not happen if you let the fixer stand still.

Hope this clarifies things. Finally, my high school chemistry of 40 years ago is useful. :)

Regards,
Bogdan

Koch, Gerald wrote: 
Fixer is heavier than water and will tend to sink unless the wash water
is kept moving.

Jerry

-----Original Message-----
From: pure-silver-bounce@xxxxxxxxxxxxx
[mailto:pure-silver-bounce@xxxxxxxxxxxxx] On Behalf Of Jim MacKenzie
Sent: Friday, April 28, 2006 12:07 AM
To: pure-silver@xxxxxxxxxxxxx
Subject: [pure-silver] Re: PMK


On Thu, Apr 27, 2006 at 06:58:53PM -0400, Hagner, Andrew wrote:

All my life I have been using the standard alkaline/acidic process. Can you describe the steps? How is the development arrested without a


stop bath or perhaps it is not needed. What is used as a fixer, just pure sodium thiosulphate? Better yet, are there any references to read that deal with the process?


My process is pretty simple, but based on the recommendations by Gordon Hutchings in The Book of Pyro. (I don't claim to have the knowledge of chemistry that is definitely had by some on this list.)

I develop normally. I use a 60-second running water wash (at developer temperature, usually 20 degrees), a 3- to 6-minute fix in Photographer's

Formulary TF-4 fixer (longer for T-grain emulsions and with less fresh fixer), and a 15-minute wash in developer-temperature water (gently running). I empty out the tank a few times during the wash (maybe 4-5 times), although I understand that fixer is less dense than water and floats out anyway.

The wash exceeds the recommendations, but it makes me feel better.

Jim
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--
________________________________________________________________
  Bogdan Karasek
  Montréal, Québec            e-mail: bkarasek@xxxxxxxxxxxx
  Canada

                  "I photograph my reality"
__________________________________________________________________


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