The novel 3D-contact angle method to control pretreatments

 
Controlling the efficiency of cleaning or pretreatments processes is an vital check prior coating application in order to prevent common coating failures. Contact angle measurements are the recommended tool of choice for this task and are since decades based on the same principle of analyzing a 2-D projection or shadow image of a drop placed on the surface. Known obstacles of these methods are difficulties in automatic base-line detection or the loss of 3-D information for non-round drops. In this talk we will for the first time introduce our novel 3-D contact angle method. This method is based on the principle of deflectometry: two cameras analyze stereoscopic images of light patterns projected onto the drop surface. We will explain the theoretical background of this novel method highlighting its redundant analysis method. Further, we will present a thorough experimental study comparing this method to the traditional 2D method on a vast variety of samples and thereby assessing the differences in quality and type of obtained data. Finally, we will discuss drawbacks and advantages of this method highlighting the opportunity of a 100% user independent wetting test.