Don't know if we are talking about the same technology.

I used to print on PET roll material, and before the first ink roller is applied, the substrate undergoes corona treatment.

If we had any problems with the ink not sticking on the substrate, we would have to measure the effectiveness of surface treatment. We use a test solution (most accurate), or test pens (good enough) to test surface tension, measured in dynes/cm. As a rule of thumb, Printing on PET needs a minimum of 42dyne/cm.

My understanding of the corona treatment is that the surface is deformed to increase surface area. But I think there is another school that thinks corona treatment creates microscopic pinhole in the substrate.

There is a lot of information about Corona Treatment from the world of Narrow Web Printing, perhaps some would be useful to you.

http://www.corotec.com/techinfo/papers.html