I believe that stamps are usually hinged back onto the cover during the expertization process.
I was reading an authentication on line for a stamp with a grill. The person said that the stamp was lifted from the cover to check the grill and the picture on the form showed the stamp still on cover. Does this mean the stamp was lifted, checked and then re-attached to the cover. No picture showing the grill was included on the form, this seems a bit odd to me.
re: question about grills
I believe that stamps are usually hinged back onto the cover during the expertization process.