For determining flakiness index. Particle is flaky when its thickness (smallest dimension) is less than 0.6 of the mid-size of the sieve fraction.
Gauge has seven, labeled slots for manual evaluation of particles in the seven openings. The mass of all flaky particles (passing appropriate slots) as percent of the sample is the flakiness index. Gauge is enameled sheet metal with clearly marked sieve fraction ranges for each slot. Standards BS 812