Jane, The emulsion on the new ILFORD Delta 400 Professional is the same for both the 35mm and 120 versions. The base material is different, which may be causing the difference you see. Also, it is possible that you are seeing a slight amount of residual sensitizing dye. This will not have any noticable effect on printing on either graded or Multigrade paper.(posted 8498 days ago)David Carper ILFORD Technical Service