It has been some time since I have had any of my students use roll film and they are having a build up of denisty along one edge of the film. It seems to me that this was an agitation issure, but as I have not had this problem nor have had to deal with this issure I am having remember if this is true. I am very familar with "bromide drag" with 35mm film but not with 120.
Would appreciate a jump start to old brain cells.
Just a couple of quick things, you've probably already thought of these...
1) Presoak The film prior to pouring in the soup.
2) Are they using enough solution to cover the reels all the way? (My first instructor told all the beginning students to use the same amount of solution. I have several tanks by different manufacturers, all need different amount of soup.
3) Are they using plastic or stainless reels? I have heard that some people have buildup with plastic reels. I have not noticed this myself.
Hope you figure it out!
If I am developing roll film and it is just one roll, I alway put the extra reel in and the reel with the film is at the top of the can. That way it (I think) will reduce the air bells and it requires you to fill the can to the top. Been doing this for 35 years and for me it seems to work.
thanks, yes we did discuss the amount of solution per roll size.
I hve not pre-soak film in tooooooooo many years, but I will suggest that as a possible. Also review using steel rather than plastic reels. Just wanted to be sure I hadn't missed something along the way.
The cause of this build-up could be plastic reels of an older type but most of all too vigorous agitation of the tank. If I have to process a singele 120 film I will use a steel tank and reel.
I used plastic reels in a rotary processor and I had an edge issue untill I started pre-soaking. Since then I have no issues