And What Do They Measure

• Direct observation (image analysis) – usually some 2-D representation of a particle. Which dimension is viable?;

• Sieving – combination of particle size and shape;

• Sedimentation – settling rate. Stokes Law (spheres, straight line settling);

• Coulter counter – electrozone sensing;

• Gas absorption / Permeability – surface area. Extrapolate to average particle size only. – BET (SSA back extrapolation to size);

• Light scattering – equivalent scatterers ;