Development and validation of a method for the determination of mottling as an application defect in automotive paints

Abstract

In the field of automotive coating paint aesthetic value is becoming increasingly more important in addition to its primary purpose of protecting a surface AkzoNobel Car Refinishes, a branch of the multinational AkzoNobel that works in the automotive coating in the plastic section, has been trying to equal the colour of the plastics parts to the colour of the rest of the car according specifications for approximately seven years and achieve quality paint in order to obtain a homogeneous colour car. One of these car coatings is the metallic effect, characterized by presenting reflection changes which will vary according to the angle of observation. While painting, one of the problems of metallic paints is cloudiness (mottling), this appears on the surface as fuzzy spots in different shade. This problem is accentuated in lighter colours, so the paint used in this is a light silver shade, Rhodium Silver. Nowadays the evaluation of the default of mottling is visual, therefore, subject to the perception of the person who carries it out. That’s why the Altana Group branch, BYK - Gardner has developed and created a measuring instrument called cloud - runner for the detection of mottling. The purpose of this device is to make an objective assessment of the defect. As the cloud - runner is still in beta testing, AkzoNobel Car Refinish and BYK - Gardner have reached an agreement to run a study of the device. This agreement is beneficial for both companies as it allows BYK to test their device together with a leading enterprise and AkzoNobel to have the opportunity to test their paints and coating methods and get information about a device that will on the market some time in the future...