Blue and yellow shifts in C-41 development

[pentaxpete]

I wonder if the water I have been using has 'Chloride' in it ? Wife bought a water filter jug with a 'BRITA' filter element. I have found the last C41 developer mix was giving under-development - I cut the amount of ' Starter' used to see if that was the reason -- too much 'Starter' .

 

[koraks]

Assuming that a Brita filter uses polystyrene sulfonate for its ion exchange action, there should not be an addition of chloride ions to the water. The mechanism is that sodium ions that are stuck to the polystyrene sulfonate are released into the water and that calcium and magnesium ions from the water are replaced by them in the polystyrene sulfonate matrix. At some point, all the sodium will be 'used up' and the filter needs to be replaced or revitalized by passing salt water through it to replace the calcium/magnesium back with sodium.

Ideally an ion exchange water treatment filter should not impart any chloride to the water, so my earlier remark that this may have been the problem causing the blue/yellow shift may not have been accurate. In any case, a filter using resin beads under normal operation should not impart chloride ions to the filtered water. I can very well imagine, however, that a brand new filter or a filter that has just been regenerated may contain some excess salt that ends up in the very first batch of water that is passed through the filter. This should however be quite minimal.

 

[pentaxpete]

Just had THIS e-mail from the BRITA Company --

r Elgar


Thank you for your email.


Ion Exchange Resin

This is a pale coloured particle, which works like a magnet (negatively charged). It attracts and traps calcium ion (limescale) from the calcium carbonate in the tap water as well as heavy metals (lead and copper). This improves the taste of tap water and reduces the scale on your kettle and the unsightly scum on hot beverages.


Our Cartridge does reduce chlorine, the disinfectant, but it does not take out chloride, as chloride is an Anion and we do not reduce Anions.


I hope this helps but if you do have any further enquiries please don’t hesitate to contact us again.


Best wishes

 

[Cholentpot]

Assuming that a Brita filter uses polystyrene sulfonate for its ion exchange action, there should not be an addition of chloride ions to the water. The mechanism is that sodium ions that are stuck to the polystyrene sulfonate are released into the water and that calcium and magnesium ions from the water are replaced by them in the polystyrene sulfonate matrix. At some point, all the sodium will be 'used up' and the filter needs to be replaced or revitalized by passing salt water through it to replace the calcium/magnesium back with sodium.

Ideally an ion exchange water treatment filter should not impart any chloride to the water, so my earlier remark that this may have been the problem causing the blue/yellow shift may not have been accurate. In any case, a filter using resin beads under normal operation should not impart chloride ions to the filtered water. I can very well imagine, however, that a brand new filter or a filter that has just been regenerated may contain some excess salt that ends up in the very first batch of water that is passed through the filter. This should however be quite minimal.

Makes sense. I'm going to try next time with distilled water and more rigid temps to see if I can get it back up to snuff.