ISO 19399:2016 specifies a destructive method for determination of the dry film thickness, in which damage to the coat caused in a definite manner is evaluated microscopically. The method is suitable for almost all coat-substrate combinations and also allows determination of the single film thicknesses of coating systems.
The method cannot be applied or can only be applied with restrictions in case of
- too soft and/or elastic coatings (no recognizable scribe or drill hole can be observed),
- hard (cannot be scribed/drilled) or too soft and/or elastic substrates,
- too low visual contrast between the coating and substrate, and
- film thicknesses that are larger than the depth of field of the measuring microscope.