Disodium EDTA

[Terrence Brennan]

I am in an area with very hard water; I mix D-76-type developers, as well as D-23, and I will soon be mixing D-72 and my own rapid fix. In this thread ((there was a url link here which no longer exists)), PE suggests the use of Disodium EDTA when one mixes with hard water.

My questions are:
1) how much per litre of mix should be added;
2) is the Disodium EDTA added at the beginning of the mix, and
3) if I am already mixing a developer, how will its addition affect the developer, in the sense of will it make a big change to development times?


Any input on this would, as usual, be greatly appreciated!

 

[Gerald C Koch]

I would suggest that you simply mix the developer with de-ionized/distilled water. This way you will not only avoid the calcium but also other metal ions such as iron.

 

[Terrence Brennan]

Disodium EDTA, one more time...

Hi, APUGgers...

I got only one reply to my query...I have even tried making this post in (gasp!?!) bold characters.

Is there anybody who might have some practical information for me? I mean, I don't want to have to resort to underlining my request as well!

 

[Photo Engineer]

Use about 5 g/l of Na2EDTA / liter. Use more if you get scum or the developer is cloudy. Check the pH if possible to make sure it stays the same. It should, but checking never hurts.

PE

 

[georgegrosu]

Chemical for reducing the hardness of water (sodium hexametaphosphate, calgon, Na2EDTA) is added to developer for prevent formation of „calcium network”. If the preparation of developer use high hardness water is a danger of calcium and magnesium carbonate precipitation. They should preferably be submitted to the film surface, forming calcium network. Sodium hexametaphosphate, Calgon or salt of Disodium EDTA prevents this inconvenience forming soluble calcium and magnesium complex. Hexametaphosphate concentration does not exceed 2 g / l. Calgonul is used at concentrations of 2 -4 g / l. For Na2EDTA PE gave a recommendation.
To reduce water hardness substance is dissolved first.
Substance use to reduce water hardness is good to make where is necessary (calcium network).
George

 

[Gerald C Koch]

BTW, never add EDTA to ascorbate developers such as Xtol as it will cause the sudden death syndrome.