The wettability of a powder is important, especially in chemical and pharmaceutical technologies when considering the manufacturing process and the properties of the final product. However, contact angle methods for powders are problematic. The common measurement techniques are the sessile drop method and the liquid penetration method. In this work the determination of contact angles of powders by liquid penetration is considered. In particular, we investigated the influence of the sample preparation and sampling device on the wetting process. A bulk with constant properties during the measurement must be guaranteed. We postulate a packing procedure to obtain reproducible measurements by ensuring constant powder properties. Further we determine a constant alpha = alpha(1) * alpha(2), with a(1) describing the fluid properties and alpha(2) describing the wetting of the powder system.