c41 dip'n'dunk overdeveloped corners

[flemo]

Hello fellow scheimpflugers!

I am in school at present with a c41 dip'n'dunk machine at my disposal. Quite a luxury, however, I keep getting overdeveloping around where the clamps grip the (4x5)film.
It happens quite often but in a seemingly arbitrary way - sometimes the corners on the left have the problem while the right side is totally fine and sometimes it does not happen at all and sometimes all four corners are affected.
I have tried washing the frame and clamps thoroughly before use but that doesn't fix the problem.

Does anyone in here know what might be the problem?

thanks in advance!

best
Flemming

[mdarnton]

What's your agitation cycle? I suspect you need less, and with less vigor. I find that it goes best when I move things very slowly, relying on drainage rather then vortex-like forces to move developer around. If you're going to be energetic, keep it short, rather than prolonged.

[koh303]

The problem is the pressure around the clamps before and during the process. There is no way around in dip and dunk, thats just part of the process. The solution:
Do not use that 15% area of the negative, or do yourself a favor upgrade to a Jobo.