Hypo Clear Formulae: Any tried and tested suggestions?

[koraks]

Your need for it may depend on the water you use.

Water is not buffered, so regardless of the water used, if you add some sulfite to it, pH will rise to somewhere between 8.0 and 10.0 depending on concentration and temperature. So the 'need' to adjust pH is there regardless of the nature of the water one begins with. Btw, this 'need' is IMO kind of debatable to begin with since gelatin emulsions soften at a higher pH, which actually helps washing. Unless prints are soaked for an extremely long time in the solution (for which no need exists to begin with), it's not really necessary to reduce the pH of a sulfite solution. Plain sulfite will work just fine.

 

[Mike Crawford]

Mike,

Mixing your wash aid in distilled water would certainly solve your hard water problem and alleviate the need for EDTA. If you end up not using distilled for the wash aid, you should really do so for film for a final 3-5 minute soak in wetting agent before hanging your film to dry. Use this one-batch and you won't have hard water spots on your film. Paper isn't as finicky and doesn't need that.

Best,

Doremus

Hi Doremus

Yes, think the issue has been the hard water, but will be testing a formula with EDTA when I'm close to running out of the Kodak. I don't process as many films as I used to, but always mix the wetting agent with still mineral water as otherwise is possible to get marks.

 

[Doremus Scudder]

As I understand it, the role of the Sodium Bisulfite is to ensure that the pH of the working solution is appropriate. Your need for it may depend on the water you use.

The bisulfite gets the pH to the optimum point where the emulsion gelatin swells most, enabling a faster ion exchange and, thus, faster removal of thiosulfates.

Doremus

 

[JPD]

Hi Doremus

Yes, think the issue has been the hard water, but will be testing a formula with EDTA when I'm close to running out of the Kodak. I don't process as many films as I used to, but always mix the wetting agent with still mineral water as otherwise is possible to get marks.

I hope you mean demineralised water?