3: Fineness of Dispersion -- Passing the Test with 3M™ Ceramic Microspheres:

Particle fineness affects a paint's color strength and uniformity, gloss and hiding. The presence of large particles or agglomerates can result in blotchy color. Some extenders, like calcium carbonate, wollastonite or mica, have uneven, jagged particles. 3M brand ceramic microspheres pack tightly and evenly space pigments to improve color acceptance and give a smooth, even finish.
To check the fineness of dispersion, we use an ASTM test commonly called a Hegman grind.