Methods for the determination of the following characteristics of the test pieces after washing are specified: intrinsic greying, intrinsic yellowing, increase in organic deposit content, increase in incineration residue, overall decrease in breaking strength, decrease in breaking strength resulting from chemical degradation of cellulose due to laundering and from mechanical factors in laundering. Annexes contain the determination of increase (or decrease) in degree of whiteness and of chemical wear and further a grey scale and the measurement of reflection.