Solution proof trimline coating

I electroform Nickel Cobalt and Nickel forms from 18/8 stainless mandrels. I use acid resistant tape to mark the trim line, which has to be repaired/replaced every time an electroform is removed. This is time consuming. I now have a job which requires 3 times faster turnaround, so can anyone help regarding any type of permanent/semi permanent coating which can be applied to the mandrel which will act as the present tape does, but which requires no maintenance/retapes/repairing breaks, etc. I have been told there is a "ceramic?" coating, and a "rubberized"? coating, but I am in the dark here! The bath is at 65 °C with air agitation, immersion time up to 24 hours.

All suggestions are very gratefully received.

I don't know what shape you have but a lexan cup shield could be carefully machined to fit tightly around the mandrel.