Non-porous surfaces include glass, processed metals, leather and plastics, and they are further divided into rough and smooth surfaces. Non-porous smooth surfaces include glass and painted or varnished surfaces. Non-porous rough surfaces include textured surfaces like vinyl and leather.
Examples of porous surfaces include cardboard, paper and untreated wood. Porosity is defined by the spaces within the material's surface. Glass, plastics and processed metals are produced by melting the basic ingredients and then cooling them down, creating a uniform surface with no cavities. Porosity affects certain industries; for example, rock porosity is needed when drilling an oil well due to economic reasons. In latent fingerprint recovery, the surface porosity dictates which method is used to retrieve the fingerprint. A non-porous surface is processed immediately, because the print is on the surface and becomes distorted during travel.