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.