The surface energy determines how much energy is needed to break the chemical bonds when a new surface of a solid or liquid is created. It is used to describe wettability. This is particularly important when materials such as plastic are to be bonded, painted or printed. If a surface is highly energetic (polar), the adhesion of printing inks or adhesives to it is considerably higher than with low-energy (non-polar) surfaces. For liquids, it is equal to the surface tension.