Our customer requires us to test the resistivity of the conversion coating applied to aluminum parts. Our customer claims that the values they measure are much higher than the ones we report. We verified this by taking a measurement immediately after the coating process and then storing the part for a month. The second measurement, taken at the same location on the surface, is much higher. What is going on? I. W.
More than likely, the increase in resistivity after storage is due to the conversion coating dehydrating. If this measurement is really critical to your customer then the parts should be stored differently than the way they are being stored right now. A controlled humidity environment should help solve this problem.