Coupon

A small, flat portion of material of construction typically used for laboratory cleaning evaluations

Coupon is defined in PDA TR29, Points to Consider for Cleaning Validation, as "A small, generally flat portion of a defined material of construction (such as stainless steel or PTFE) and of a defined surface finish, typically used for laboratory cleaning evaluations and/or for laboratory sampling recovery studies.". When undergoing cleanability sudies, swab qualification, and visual inspection qualification a coupon representing the actual equipment surface is used. This allows a representative of the equipment to be soiled and tested on without risking damaging the actual production equipment.