The colour of a pre-wash...

[Nige]

Ok, maybe this should go in another section, but anyways...

It's been so hot recently that I've added a pre-wash to my routine to get the film and tank at a more friendly development temp before pouring in the developer.

So why does the anti-halation rinse off coloured (blue in the case of the J&C Classic Pan I was developing, Pink for the Delta 400) but if I don't do the pre-wash and just pour in the developer, when I pour it out, it's clear (or whatever colour the developer was to begin with)

hmmm?

 

[Photo Engineer]

The prewash water contains some AH dyes and also acutance dyes added to the emulsion to enhance sharpness. It also includes trimmer dyes to adjust spectral sensitivity and to adjust or fine tune speed.

Some of these dyes are sensitive to pH and therefore are one color in water and another color in base (developer solution).

Each manufacturer uses a different mix of dyes for each product.

PE

 

[Nige]

very interesting!

thanks, PE!