The first step involved concentrating the material. The precise mechanism depended on the type of carrier substance or asbestos - not an easy task given that the test matter can vary from liquid to solid. The concentrate was then subjected to a standard test. Standard techniques were too harsh so the partners developed a gentler method. The danger of overgrinding would destroy the fibres but too little grinding would not yield particles of the right dimension.
Shape is a defining characteristic of asbestos.
This is where microscopy is needed. Traditionally, asbestos fibre volume is calculated by assuming either a circular or square cross-section. In truth, the reality can be somewhat different and this can cause problems. The researchers lessened the margin of error by developing theoretical and experimental methods for approximating the fibres' true shape and volume, including an efficient counting scheme and an improved eye-piece graticule for the microscope. A commercial firm has the task of producing the graticule and supplying it.