Sunday, 22 February 2015

Green Developer?

 ID11 used with Fomapan
In the normal run of things the colour of your developer as you pour it out at the end of the developing period is nothing out of the ordinary. You just get on with the next stage of the process. That is until it comes out emerald green!. What was just another film processing session has just thrown up a number of questions of doubt, or has it? This is possibly the first time for quite a while that you have taken any notice of what colour the used developer was supposed to be. So what changed? Your film make?

Basically what you are seeing, if you have not used a pre-soak, is the anti-curl and/or the antihalation coatings, washing off in the developer. It has no affect on the developing process which is the first thought most of us have when presented with something out of the ordinary. Different developers can present varying colours depending on which film manufacturer you use.
RO9 used with Fomapan

Why add these dyes?

The halation dye is added to the back of the film base to stop reflections coming off the backing (Acetate or Polyester) into the emulsion, causing exposure affects, usually visible to the eye as halos around areas of brightness. Sometimes the halation coating is sandwiched between the film base and the emulsion or added to the film base itself giving it a slight tone. This in no way alters the way the film acts with the printing process.

So which film developer combination gives you this wonderful Green?

Fomapan is responsible for the green tinting of the used developer. The developers I have used - ID11 and RO9 have produced this colour, so suspect that this film may affect other developers. Although Foma produces the most striking colour, other makes also add a tint to varying degrees to the developer during the process.