Variable contrast papers, developers and contrast control

[abeku]

Dear all,

I've recently been adopting variocontrast paper (Forte polywarmtone) in my printing and I've noticed that the contrast is dependent on the dilution of the developer (and consequently how exhausted the developer is). When compared to the graded paper I otherwise use, Emaks K888 (J&C Expo), the same diluted and exhausted developer (Neutol WA) doesn't seem to affect the final result that much.
The questions I have are: Are variocontrast papers in general more sensitive to dilution of the developer, or is it unique to wamtone papers? Is there a difference between warmtone and coldtone developers with regards to contrast control? If so, which ingredients in the developer are causing this?

cheers,

Abeku

 

[Ole]

In general, warmtone papers are far more sensitive to developer variations than "normal" or cooltone papers. I have almost stopped using variocontrast papers, since I find I have much better control by adjusting the developer and using graded warmtone papers. There are many ingredients in developers that affect image tone and contrast, with coldtone developers generally giving higher contrast.

 

[Neal]

Dear Abeku,

If you are going to use VC papers it is important that you make sure you are always developing to completion. The object of them is to vary the contrast by varying the exposure to the different contrast layers rather than by modifying the development. Personally, I have found the Forte Polywarmtone does take longer than Ilford/Kodak to reach full development so I would guess that any reduction in developer activity will affect it.

By coincidence, there is an article in the latest Photo Techniques that disucsses how the length of development time affects Ilford MGIV VC paper.

Neal Wydra