This part of ISO 8130 specifies a visual method to determine the deterioration of surface quality of the final coating when mixing two different coating powders. The surface quality will depend on the following characteristics of the coating powders: a) the chemical reactivity; b) the chemical composition; c) the melt properties. The onset of the incompatibility in appearance, its nature and its extent will depend greatly on the ratio in which the powders are mixed. The nature of the incompatibility in surface appearance may manifest itself in various ways, described in Clause 8. This test is useful in predicting the possibility of incompatibility arising from mixing different powders both during the manufacturing process and during the application of the coating powder. This part of ISO 8130 concerns only changes in visual aspects of the coating. The mixture series can also be used for testing properties such as mechanical properties, chemical properties, corrosive properties and resistance against UV radiation. Further properties can be agreed between interested parties.