Problem solved... another one arise...
Hello all,
First let me thank you all for your inputs (right or wrong), they really cheered me up and helped me remain coherent and methodical about all this (as opposed to feeling doomed and making the same mistakes again and again).
So definitely an under-agitation problem in two ways :
1st. Not enough inversions during the first 30s/1min. And maybe after that but I need to test for this and know if, with proper agitation at first, I can slow down afterwards to gain back some control over contrast and grain. As well as see if I can use semi-stand (3min intervals) agitation again which I find very rewarding.
2nd, and probably most important, I didn't apply enough force during my inversions. They needed to be more brisk. Kind of like trying to empty a yoghurt pot (well maybe not as much but you get the idea). This is probably more true with stainless steel tanks than with the Jobo ones which offers a better flow of the chemistry (hence the fact that my problem was more obvious with the ss tanks).
Well now that I get a perfectly even development a new problem arose

:
It happened before and when I mentioned it I thought it was due to my testing of extremely slow agitation. Unfortunately it was not and it happened again with my new proper and energetic method on my last test roll.
As you can see on the picture there is a thick white line going across the image showing over development. I darkened it and added contrast to make it more obvious. It is continuous on all frames as if a drop of developer acting more intensely crossed the whole film. But the direction of the line in the developing tank is parallel to the ground and the lid.
It only happened twice and only in my recent agitation testings. Since then, I just finished developing one of my week end film in PMK and there is nothing of the sort.
What the two developments had in common was
1. The use of HC-110 freshly diluted from syrup. Can it be possible that this is due to one drop of syrup than didn't dissolve well ? Is sounds like a stretch especially considering the direction of the line (parallel to the ground). Does HC110 needs time after dilution in order to dissolve properly (I've just started using this developer so I'm not familiar with it) ? Or maybe a good shake ? I only stir it.
2. I didn't use my usual demineralized water but just plain tap water for one and plain tap water filtered with a Brita for the other.
Appart from that I'm clueless... :confused:
Can that artifact still be due to some improper agitation ?
Again thank you all for your help, and I hope someone has an idea about this one...
Vania