I LOOOVE the look of a mica swirl top. However, I have had a series of frustrating attempts at different effects. I am hoping someone can shed some light on this for me? When I use a specific mica, I get these "divets" or pits or pockets or holes, however you want to describe them. Sometimes, I don't. What causes this? Am I using TOO MUCH mica in my oil? I have had a few successful attempts at the mica swirl staying nice and even on top... Any Ideas?