If required by the client, white- or light-coloured leathers can be tested with a black felt. Slight discoloration of the leather, due to colour rub一off from the felt, may be possible. In this case, do notassess the change in colour of the leather. This shall be assessed after rubbing in a different place with a white felt.8.7 Using D65 illumination according to ISO 105-A01, visually assess the change in colour of the leather (5-7) and the staining (5-6) of the pieces of felt with the grey scales in accordance with ISO 105-A02 and ISO 105-A03. For the assessment of the felts after the test, reference felts shall be used which have been treated in the same way as the tested felt. For example, for wet test, the reference felt is wettedwith water and dried. The reference felt shall be from the same supplier and the same production batch as the felt used for testing.Note any other visible changes in the surface of the specimen, for example loss of gloss, development of polish, flattening of the nap or destruction of finish. Possible destruction shall be assessed without anymagnification.8.8 Alternatively, provided the staining and colour change is even, the grey scale staining and colour difference can be assessed instrumentally (}$) in accordance with ISO 105-A05 and ISO 105-A04,respectively9 PrecisionFor the visual grey scale evaluations, an inter-person precision of 10,5 grey scale units is normal.10 Test reportThe test report shall include the following information:a reference to this document;a description of the type of leather tested;an indication as to which surface of the leather was tested the conditions under which the leather and felt were conditioned before testing and the type of felt used (white or black);a) b) c)d]e) the number of cycles completed;f) the numerical grey scale ratings for the change in colour of the specimens and for the staining of each piece of felt;g) details of any other visible change in the surface of the specimen;h) details of any deviations from the method specified in this document.