Hiya, 

Is it possible to use sound waves or another means to take measurements from a plastic coated surface? For argument sake let's say we have 10 seemingly identical plastic coated sheets, by using sound waves or something else is it possible to take measurements from the surface which would allow you to differentiate between them  from non visable differences brought about by variations in the coating and manufacturing process? 

 

Many thanks, this is a great site and all the helpful people on here. I am learning a lot. 

Yes indeed, Billy.
I have used ultrasonic coating thickness meters in the past.

https://www.google.co.uk/search?source=hp&ei=0pmZXramO-6AjLsP1pqAuA4&q=ultrasonic+coating+thickness+meters&oq=ultrasonic+coating+thickness+meters&gs_lcp=CgZwc3ktYWIQAzIGCAAQFhAeMgYIABAWEB4yBggAEBYQHjIGCAAQFhAeMgYIABAWEB4yBggAEBYQHjIGCAAQFhAeMgUIABDNAjoFCAAQgwE6AggASjMIFxIvMGcyMTJnMGcxNzBnMTc0ZzExMGcxMTZnMTE0ZzExNGcxMDhnMTQxZzE2NmcxNzNKHggYEhowZzFnMGcxZzFnMWcxZzFnMWcxZzVnNGcxNVDWCli4UGDaUWgAcAB4AoABkgOIAbojkgELMTEuMTkuMS4yLjGYAQCgAQGqAQdnd3Mtd2l6&sclient=psy-ab&ved=0ahUKEwi2162btO_oAhVuAGMBHVYNAOcQ4dUDCAg&uact=5