[pure-silver] Re: PMK


----- Original Message ----- From: "Koch, Gerald" <gkoch02@xxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Friday, April 28, 2006 8:55 AM
Subject: [pure-silver] Re: PMK


You are wrong.

Just because a solution is miscible with water does not mean that it will immediately disperse within the entire container. Try this experiment. Add a drop of ink to a glass of water that has sat for a few minutes in order to become still. You will see the ink slowly sink towards the bottom of the glass. Stirring the mixture will make the ink disperse faster.

I was not implying that the fixer would forever remain at the bottom of the tank.

I've done this with a solution of water soluble dye. The dye forms a cloud which moves in all directions until it diffuses into the bulk of the water. Of course, if the dye solution is not very soluble in water or if its specific gravity is large, it might sink as it diffuses. I think this is not quite what happens to hypo, which is in a fairly diluted form when the print enters the wash water. Even though the concentrated hypo at the surface of the emulsion will tend to sink as it diffuses the sinking will probably start some circulation by means of convection. The convection will increase the rate at which the diffusion occurs. I am not sure how to prove this. Perhaps a dye that binds to thiosulfate but does not affect its specific gravity would do. I have no idea of what sort of dye would be satisfactory.

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

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