I recently went from using the same razor every day to alternating between several different razors (RAD has set in). I recently noticed that after picking up a razor that I hadn't used in a week or so, the shave has been irritating. Both times were in a razor that I had previously shaved before with a Derby blade used two times (once with a Tech and once with a Parker 65R). I usually get 5-6 shaves with a Derby with no trouble. When I removed the blades, they almost appeared to have a little corrosion on them. Should I remove the blades after each shave and dry them? Should I stick to one razor at a time? Is it the Derby blades? I tossed an Iridium that I used twice because I didn't want to experience that irritation again.