What effect does micron size have?

The micron size dictates how much luster and reflection a mica has. The higher the micron size the more sparkle but less coverage (opaqueness). A natural mica with a micron size of over 150 is not allowed to be used on the face in the US. This is the reason some of our larger micron micas are approved for general cosmetic use but are not to be used on the face. This may seem nonsensical since wearing glitter around the eyes and on the lips is currently trendy. Plastic glitters are not approved for this use in the US but the FDA at this time is currently not enforcing this law until they have come up with a more solid ruling. 

The main concern with large micron glitters and micas on the face is that possibility that they might get into the eye area and scratch the cornea. There are very few instances of this ever happening but worth noting that if you choose to use large micron glitters in your products your do put yourself or your company in a position of liability for this reason.

Particle Size 15 µm or less = low luster, good hiding power
Particle Size 2-25 µm = silky luster and strong hiding powder
Particle Size 10-60 µm = pearl luster with medium hiding power
Particle Size 10-125 µm = shimmering luster and low hiding power
Particle Size 20-150 µm = sparkling luster and transparent
Particle Size 45-500 µm = glittering luster and very transparent