The nominal diameter of the 4000 Series of particles is calibrated with our NIST traceable microscopy methods, while the size distribution and uniformity is measured by electrical resistance analysis or optical microscopy.
Those particles with a nominal diameter from 1 μm to 160 μm are made from polystyrene, and are packaged as aqueous suspensions in 15 mL dropper-tipped bottles at an optimum concentration for dispersion, handling and dilution.