Pyro - Ilford Blue/Green Lights

[bluejeh]

My enlarger is Ilford 500 with 300watt Blue and Green lights in head (not magenta/yellow).
I use Ilford FP4+ and TriX 320 in medium format and 4x5 film sizes, Ilford variable contrast paper RC (& will soon be using) Fibre.

I recently purchased pyro PMK neg developer with Gordon Hutchings Book of Pyro, his formula produces yellow/green stain.
it sounds to me on my first reading that Hutchings recommends the traditional magenta/yellow lights.....
If you have used pyro pmk or any other pyro with a blue/green light head, what is your experience?
thanks.

 

[dmurrell]

Bluejeh,

No problem with the Ilford Multigrade Head and Pyro negs - I use a similar combination: TriX in Rollo-Pyro, printed on Ilford 500 head using a variety of papers. What confuses some people is the Blue / Green filtration - think of these colours as being complementary filtration to the normal MG Yellow/Magenta filters, so Green is opposite to Maganta and Yellow is opposite to Blue. Contrast control on MG papers papers is determined by the response to Blue or Green light (Blue increases contrast, Green reduces contrast) - all the Yellow or Magenta filters do filter out ther complementary colours, so Yellow "removes" Blue, thereby reducing (softening) contrast. And conversley Magenta removes Green, increasing contrast. The blue / green light out of the MG heads, mixed at the top of the head does exactly the same thing to the paper emulsion as you would get using magenta or yellow filters.

Now as far as Pyro stain goes, this is supposedly proportional to amount of silver so highlights (more silver) stain yellow and this reduces contrast locally, which helps retain highlight detail and tone, making it a little easier to print such things as landscapes with wide subject brightness range. In practice, the stain varies between different Pyro formulations and quite often there is a significant stain to the film base as well, requiring a bit of extra contrast in printing - usually around half a grade in the case of Rollo-Pyro in my experience. However, highlights seem to retain detail better. There is some variation betwen different formulations in the nature of the stain and amount of contrast achieved. .