Substrate (materials science)
Substrate is a term used in materials science and engineering to describe the base material on which processing is conducted. This surface could be used to produce new film or layers of material such as deposited coatings. It could be the base to which paint, adhesives, or adhesive tape is bonded. A typical substrate might be rigid such as metal, concrete, or glass, onto which a coating might be deposited. Flexible substrates are also used. With all coating processes, the condition of the surface of the substrate can strongly affect the bond of subsequent layers. This can  include cleanliness, smoothness, surface energy, moisture, etc. Some substrates are anisotropic with surface properties being different depending on the direction: examples include wood and paper products. Coatings. Coating can be by a variety of processes: In optics, glass may be used as a substrate for an optical coating—either an antireflection coating to reduce reflection, or a mirror coating to enhance it. A substrate may be also an engineered surface where an unintended or natural process occurs, like in: