Ph of working sterength developers.

[Andrew Durazo]

I've run into a problem. The water supply in my area is somewhat acidic. As a result my developers are not working at full strength. I can solve this with a little alkaline solution but, how alkaline should it be? Does anyone know the Ph of working strength Clayton P-20 and Clayton F76 plus?

Thanks for the help

Andy Durazo
Instructional Assistant Photography
East Los Angeles College

 

[jim appleyard]

One solution would be to mix your devs with distilled water.

 

[Andrew Durazo]

One solution would be to mix your devs with distilled water.

Thanks Jim but that is not economically feasible. I run a college darkroom; 33 B&W workstations. Depending on volume the lab will be set up once or twice a day.

 

[Rudeofus]

You could at least mix 50ml of a test batch with distilled water and measure its pH as a reference. This would likely be more accurate than all pH values you'd find posted on the net.

 

[Martin Rickards]

I'd hazard a guess that the amount of buffering salts in any commercial developer are likely to be sufficient to raise the pH levels to where they should be. The only exception I could see is a Rodinal type at dilutions of 1:100.

 

[koraks]

I'd hazard a guess that the amount of buffering salts in any commercial developer are likely to be sufficient to raise the pH levels to where they should be. The only exception I could see is a Rodinal type at dilutions of 1:100.

I agree. In most commercial formulas, buffering will overcome the minor variations in pH of tap water. Keep in mind that the pH scale is a log scale, so 0.5 points deviation around 7 is not the same in absolute terms as a .5 difference around 9.

 

[Doremus Scudder]

Any tap water that's safe to drink will more that likely work just fine with commercial developers (which contain sequestering agents and buffers just so they will work reliably over a wide range of common pH values). What you might have to do, if the developer is slightly less active, is adjust your developing time accordingly.

I had rather alkaline water in my apartment in Vienna and had to shorten my development times by about 10% in relation to my times for the same developer in the U.S.

Just run a test or two to arrive at your new developing time. Tweaking the developer by adding an alkaline may have unintended negative effects.

Best,

Doremus

 

[RalphLambrecht]

I've run into a problem. The water supply in my area is somewhat acidic. As a result my developers are not working at full strength. I can solve this with a little alkaline solution but, how alkaline should it be? Does anyone know the Ph of working strength Clayton P-20 and Clayton F76 plus?

Thanks for the help

Andy Durazo
Instructional Assistant Photography
East Los Angeles College

I 2nd the advise about distilled water and like to point out that some dev recipes note target pH values but they are certainly all different.

 

[Martin Rickards]

I 2nd the advise about distilled water and like to point out that some dev recipes note target pH values but they are certainly all different.

And most distilled water is mildly acidic due to CO2 absorption.

 

[Sirius Glass]

Go to the chemistry department and learn how to set up water distillation equipment. The set up the equipment to double distill the water.

 

[GLS]

I'd hazard a guess that the amount of buffering salts in any commercial developer are likely to be sufficient to raise the pH levels to where they should be

Yes the alkaline accelerants used in the developers should be more than sufficient to overcome any minor variance in the water pH.

Go to the chemistry department and learn how to set up water distillation equipment. The set up the equipment to double distill the water.

On the scale of use he's talking about I doubt this would be very feasible. Distilling large volumes of water is a time consuming process, and also highly energy intensive. This is why water is no longer de-ionised in this way in routine production; instead typically ion-exchange resins are used in a flow system. The chemistry department may have these types of machine.

 

[Martin Rickards]

The EPA recommended lower limit for pH of drinking water is 6.5, which is significantly less acid than water saturated with CO2. . .

 

[Rudeofus]

In theory drinking water should be nice and clear and should not contain lead and should not contain enough iron/copper to overcome the sequestering agents in XTol.

I gave Andrew a simple and very economical procedure to find out whether water quality is actually the issue, and how to correct for it if it exists. He is free to go that path or not, but any discussion "his water can't be as bad as he says" is pointless IMHO.