Whitehouse Scientific is a leading producer of glass microspheres for calibration and is the highest-ranking European certification laboratory for primary methods of particle size analysis. The company’s standards cover all particle sizing techniques including laser diffraction, Coulter methods, optical sizing, sieve calibration and image analysis. Nearly all the reference materials are NIST-traceable. Ranging in size from 0.1 micron to 5.0 mm they are available as single sizes or broad distribution standards. In addition, Whitehouse offers a unique calibration procedure for NIST-traceable measurement of filter apertures between 3 and 1000 microns, and also produces general-purpose research grade microspheres. Among developments for 2010 is Whitehouse Scientific’s new opaque standard for particle size analysis, which covers the size range from 19 to 190 microns. It has been the subject of a recent round-robin exercise involving examination by leading particle sizing laboratories and instrument manufacturers. The new standard has also been analysed within the Quality Audit Scheme of independent company LGC Standards, and has produced the best ever repeatability seen by laser diffraction analysers.