Normally the pearled barley is passed through six different sieves; the set of sieves is closed at the top and bottom with the sieve with the largest holes placed at the top; the top and bottom sieves should be empty after sieving.
Two samples of pearled barley of a checked weight of between 50 and 100 grams are sifted by hand for at least five minutes, with the aid of the rubber cubes.
Sieving consists of taking hold of the set of sieves with the hand and shaking it, more or less horizontally, 120 times per minute, each shake travelling about 70 mm. This to-and-fro movement is interrupted every minute by a triple circular movement. The sieved residues are weighed to the nearest 0,1 g and expressed as a percentage of the sieved product which shall be weighed to the nearest whole number, and the average calculated.
The average of the percentages of the sieved residues should be added progressively, starting with the value 0 % in respect of the residue from the empty sieve with the largest holes. The added percentages Σ (%) and the sizes of the holes in the corresponding sieves are plotted in co-ordinated axes on millimetric paper, the Σ (%) in ordinates and the diameters of the holes, in mm, in abscissae.
The median value (dm) is the hole width expressed in hundredths of mm for Σ (%) = 50, and is read off the graph obtained by joining the points by straight lines.