[quote="Francesco"]I have been experiencing some streaking lately (the last two developing sessions) using BTZS tubes, Efke PL100 and Pyrocat HD and would like to hear what people think may be the cause of it.

First, are the streaks on the back of the film ( side in contact with tube) or on the emulsion side? If they are on the emulsion side I have absolutely no idea what the problem is.

If, however, the streaks are on the back of the film the problem could be that these areas are not getting any exchange of the developer during development. This would be especially true down the middle of the film since this is the area that comes into tighest contact with the tube. One solution is to pre-wet the film before loading it, and another is to load the tubes normally but while there are floating in the water bath dureing the pre-soak pop the caps off the tubes and gentely pull the film about half way out of the tube and then push it back in. Repeat this two or three times and then put the caps back on an continue with development.

My understanding is the Jobo recommends loading film wet into their expert drums since this drum is really just several BTZS type tubes rolled into one.