Please help me! I am having terrible trouble with drying film - the sheets look OK after they come out of the wash, but dry with outlines of runs and areas of lighter/darker density where water has drained off. The puzzling thing is some sheets come out perfectly! On average, about 50% of the sheets I dry are affect ed to a greater or lesser extent by these marks.
I've tried everything I can think of - the water in my area is hard and used to leave chalky deposits, so I tried deionised water which was a bit better. I the n invested in an RO system which eradicated the deposits entirely and has almost resulted in no drying marks at all on roll film, however sheet film is still af fected and so is 35mm to an ever greater degree.
I have used a tank to wash the film in with water feeding in from the bottom and out at the top. I have used wetting agent and found even more marking and runs . I have tried hypo eliminator at the correct interval during the washing seque nce and am not sure that it has had any noticeable effect.
For 5x7 sheet film I leave the film in the unicolor drum after processing and ri nse with 600mm of water on the motor base for 1 minute. This is emptied out and another rinse (same vol.) for 2 mins, followed by 5 more rinses of 5 mins durat ion each rinse. The film comes out clearer and more evenly developed than I've ever seen it, but after drying in my durst hot-air dryer it has these horrible m arks all over it.
I know the marks are caused during drying as I can see from the gelatin where th e marks will be - where the water has cascaded off the sheet, following a roughl y diagonal path echoing the way the film has been hung. The marks are on the em ulsion side - the other side is perfectly clear. The marks will not wash-off - they have become areas of low density in the middle of the mark with a ring of d arker density at the fringes.
I hope some of you can help, as this is driving me nuts - all my careful work an d planning is being ruined by something that I have semmingly no control over.
Sorry about the rant.