I've read many posts regading measuring the film thickness using an elcometer or similar gauge. While I believe this to be a good tool it is also important to remember this reflects the total of all layerings (phosphate, ecoat, primer, basecoat and clearcoat). My experience with automotive manufacturers while being a OEM coatings supplier has taught me certain areas to be very aware of such as the back corners of the hood where automation tends to rise to the roof while not hitting the A-post. The meat or centers of every panel generally has adequate clearcoat for sanding.