Gast
Hello,
I’ve recently carried out my first tests with Efke R100. Two rolls of film were exposed and developed identically, with one exception: unlike the second roll, I did not pre-rinse the first one. Results for the non-pre-soaked film: Wavy fogs of varying density appeared in the uniform grey of the grey card, but the density curve is (as far as can be measured) almost ideal and the ISO sensitivity was 100 ASA. With the pre-soaked film, the development was absolutely uniform, but the densities are significantly lower:
..................................................Zone I..........Zone III..........Zone V..........Zone VII
pre-soaked film...................0.05..............0.17................0.36..............0.77
unsoaked film..........0.10..............0.45................0.70..............1.00
Do Efke films need to be pre-soaked to ensure even development?
If so, by approximately what factor would the development time need to be extended?
Or should a lower speed be used instead of extending the development time?
Thanks and best regards
Harald
MirkoBoeddecker
Harald,
You’re right in your assumption.
The films need to be pre-soaked to ensure uniform development.
To protect the emulsion, the film surface is coated with a so-called supercoating, which consists of highly diluted gelatin. As efke still uses a vertical casting machine, this highly diluted gelatin layer does not always spread completely evenly across the film surface after application. With larger film formats (actually only with sheet films – I’m surprised you can already see it on roll film – I’m assuming you’re using test films with a uniform grey exposure), these ‘streaks’ appear on perfectly even surfaces if the film isn’t pre-soaked.
Pre-wetting, however, completely eliminates these streaks.
As the developer takes longer to penetrate the emulsion after pre-wetting (it first has to ‘displace’ the water), the development time should be extended.
We recommend 30 seconds, but this will need to be adjusted slightly on a case-by-case basis.
Best regards,
Mirko
MatthiasS
Does leaving the film to pre-develop for too long actually do any harm – or does it affect the final result? In theory (in my mind), it shouldn’t, but I thought I’d better ask just in case...
Best regards,
Matthias
