Figure 1: Diagram of the 4-field test [10] showing test surface (20x50 cm) with four test fields (5x5 cm) and stipulated wiping route of the wiping cloth. a=50 cm, b=20 cm, c=5 cm, d=10 cm, e=5 cm; the f and g dimensions of the unitary weight were at least 8.6 cmx12.1 cm, respectively, the block weighs 2.5 kg. The wiped area includes fields 1–4 with the turnaround at test field 4. Test field one is contaminated [10].