Press O Film is a very simple technique to measure a surface profile. The foam side of the Flim is used to mold the peak-to-valley profile of the surface and then the measurement is taken by the mechanical Surface Profile and Thickness Gauge.
The gauge can also be zeroed to offset the original tape window thickness (typically 50µm (2 mils). The Press O Film is a proof of test, as the film can be included in manual reports.
Whilst surface comparators provide a useful indication of surface profile the interpretation of the profile is dependent on the user and thus the use of surface comparators to determine surface profile is a subjective test.
However, produces a numerical value for the surface profile and has the added advantage of providing a ‘proof of test’ as the film can be included in manual reports (if stored correctly).