However, institutes use internal testing methods that permit absolute conclusion under specified conditions, and there is a method of testing stain soiling in switzerland : A polyester-wool mix can be used as an example of the wool soiling in mixed fibre dyeing ; Dispersion dyes colour the wool in the fibre mix by means of the direct adsorption from dye bath, or as a result of the dispersion dyes migrating from polyester onto wool. This type of soiling can be restricted by using appropriate agent (resist Agent). Alternatively it can be removed with an intermediate reduction clear, using reduction agents and/or surfactants. The following definition apply: 1. For polyester fibre:a) Dispersion with non-ionogenic product: The quantity of dye adhering to the surface depends on the type of dye used, and is usually greater in the first dyeing phase. As the dye temperature increases, the quantity decreases and generally disappears after a boil period of 30min, so that the polyester fibre ha virtually no dye left adhering to its surface.b) dissolving with acetone : the proportion of dye adhering to the surface is relatively smaller than the quantity of dispersible dye, and with this method it reaches almost zero during the course of dyeing.2.For wool:a) dispersion with non-ionogenic product: the observation of superficial dye presence is carried out in the same way as (1a), although the quantity will always be larger than on the polyester fibres. Depending on the dye used, thequantity will be at its highest when temperature is between 60 and 80 degree celsius.b) Dissolving with acetone: although the influence of the dyeing sequence on the quantity of dye bonded to the surface is similar to (1b), the quantity of dye that is soluble in acetone is proportionally larger in comparison with the dispersible dye. This is an indication that the non-ionogenic products are not absolutely efficient.