For particles that will not dissolve in water, there is the Sedigraph method---giving a good curve of particle size vs. % of total. Also the coulter Counter method. Both can measure down to below 1.0 micron size. http://www.pss.aus.net/products/microme ... /5100.html
for Sedigraph. http://www.beckmancoulter.com/coulterco ... isizer.jsp
for Coulter Counter.
Finally, the classic set of Screen Sieves ----ASTM Specifications for Sieves: http://www.astm.org/cgi-bin/SoftCart.ex ... 1195246956
Do you need to check resins, or fillers? Hope these references help.