Cover glasses, and by extension mounting media, are the cfe facto front lens of every microscope objective. Those who coverslip are, in effect, completing the assembly of a microscope objective with every cover glass they apply. So while coversliping is a tedious process, its visibly appreciable contribution should not be minimized.

There are optical reasons on which coverslipping do's and don'ts are based. It is optically and physically impossible for alternatives such as liquid substitutes and plastic film to duplicate the specifications and performance of glass cover glasses. Such substitutes are used, however, perhaps because there is so little related useful technical information available to discourage such use.