You stated that you have delveloped many 220 rolls using the identical techniques and materials? After hearing the details, I would have to conclude that the problem was a chemical one brought about by some unintentioned modification in technique and/or handling.
Originally Posted by Cheryl Jacobs
Here are some possible senerios: 1) The film was loaded properly but there was sufficient displacement in position to set up a condition where the developer was depleted in areas where the film layers were at closest proximity. Agitation in this case was just not sufficent to replace depleted developer. 2) The film was properly loaded but the developer was not entirely uniform due to (a) undesolved patriculate from a recently made up solution, or (b) dissolution of developer prior to loading due to temperature change of the stock. 3) Same as 1) except agitation caused too rapid development in the close areas.
Seems a little conflicting doesn't it? I use a modified agitation technique which I developed over the years: My technique is to invert three times, rap _hard_ three time to prevent air bells, then let it rest for a quiet minute. I do mostly 120 in a ss tank and reel and adopted this technique after recieving "bromide drag" in a 35mm reel (PXP, I think).
Truly, dr bob.