Quote Originally Posted by Henry Alive View Post
Once in a while, I get some scratches in my negatives, and I am almost sure that they appear when I clean them with a brush (Adorama brush).
Then don't do that. Seriously it's best not to touch negatives with anything but air. If you use a brush you must be vary careful that it doesn't pick up any grit. Some developers produce more softening than others.

Years ago when emulsions were softer it was fairly general practice to use a hardening stopbath such as a 3% solution of potassium chrome alum. Films are treated for 3 minutes with constant agitation. This bath does not keep for more than a day or so and must be made up fresh.

An acid alum stopbath provides a bit less hardening but may be easier to obtain.