Table 3.

 Loss of particles during washing. Absolute numbers represent the median of particles per 22 grid squares of three grids (virus) or six grids (two experiments; spores). Relative values (in per cent) represent difference (Δ) in particle number between two succeeding washing procedures

Suspension	without washing	2 washing steps	Δ (%)	4 washing steps	Δ (%)	6 washing steps	Δ (%)
Spore, 106 part per ml	19	15	24	11	24	6	45
Virus, 107 part per ml	50	42	16	33	21	22	33