Popular cleaning coupons include 316 stainless steel, PTFE, PP, aluminum, silicone and HDPE. There are a wide range of other coupons available.

HOW DO I USE CLEANING VALIDATION COUPONS?

Example: if your proposed method for swabbing involves a solvent, say methanol, how do you know if that solvent and the swabbing technique you are going to use will actually recover the residue from the surface?

In order to determine the efficiency of your swabbing method in recovering the residue, a cleaning validation coupon, matching the material of construction and the finish of the subject surface, is spiked with known amount of a solution of the residue of known concentration, dried, and swabbed with your proposed swabbing method and the swab analyzed for the residue. If the recovery of the residue is within acceptable limits, then you can proceed to do the swabbing on the subject surface.