Allesandro;

Any defect you can feel is serious indicating either a coating defect, or a rupture of the emulsion during processing. Either is a serious problem.

Another "feelable" defect is due to adhesion of some foreign particles to the surface of the film. This is less serious in that it can be removed sometimes by a rewet. Most often, this damage too is permanent as the particles embed themselves into the coating.

The quote you use from my post is indeed true, but there is more to it than that. Ilford, Kodak and Fuji, to name 3, add special agents to the film to protect against freezer damage. This includes things such as sorbitol and carbowax, which are humectants. In any case, the biggest harm to long term freezing is moisture damage and there the film emulsion sticks to the base side when rolled up. Again the big 3 take steps to avoid this.

And thanks, yes, now I see the spots. Very unusual.

PE