Holes in my enamel after grinding

Hey guys
We are a small independent watch brand ftom Brazil and after our first release, we are trying to give some depth to our brand.
We are planing a new collection with self made enamel dials and we are in the middle of the process of learning
We are having a lot of holes and bubbles in our experiments even when changing the apply tecnique, cooper cleaning method and time of firing and temperature.

Enamling is something ive yet to try but dying to.