The AST products VCA 2000 video contact angle goniometer is used to measure wetting of surfaces or their relative  hydrophobicity/hydrophilicity. Wetting, the ability of a liquid to maintain contact with a solid surface, is an important characteristic for understanding the thermodynamics of liquid-solid interactions and is playing an increasingly important role in nanotechnology. In it's simplest implementation the technique measures the shape of a liquid droplet on the surface- with water rounder drops have a high contact angle with the surface and indicate that the surface is hydrophobic while flatter drops have a lower contact angle and indicate a more hydrophilic surface. Other forms of contact angle measurement can be made with the VCA 2000, including pendant drop and dynamic sessile drop measurements. In addition, leading edge and training edge measurements can be made for tilted samples. The contact angle can also be used to calculate the surface tension. Finally, the VCA sample chamber can be connected to a gas cylinder for controlling the atmosphere surrounding the sample.