Is the anodic coating a good electrical insulator?

If you have an application where electrical conductivity is important, you should test an actual production run for this characteristic. You should also make sure that the anodizer knows this is a design parameter for your application.

The dielectric strength of an anodic coating should be approximately the same as that of Alumina. The Handbook of Chemistry and Physics, 43rd Edition, (published by The Chemical Rubber Publishing Co, Cleveland, OH) gives the dielectric strength of Alumina as between 40 – 160 volts/mil. In metric units that is 1.6 – 6.4 V/uM.