Editing Laser engraving (section)

===Plastics===
Each plastic has specific material properties, especially the light absorption spectrum. The laser irradiation can generate direct chemical modifications, melting or evaporation of the material. Plastics are rarely seen in their pure state because several additives are used such as colorants, ultraviolet retardants, release agents, etc. These additives impact the result of laser marking.

Standard cast [[Polymethyl methacrylate|acrylic plastic]], acrylic plastic sheet, and other cast resins generally laser very well. A commonly engraved award is a cast acrylic shape designed to be lasered from the back side. [[Styrene]] (as in [[CD|compact disc]] cases) and many of the [[thermoforming]] plastics will tend to [[melt (manufacturing)|melt]] around the edge of the engraving spot. The result is usually "soft" and has no "etch" contrast. The surface may actually deform or "ripple" at the lip areas. In some applications this is acceptable; for example date markings on 2-litre soda bottles do not need to be sharp.

For signage and face plates, etc., special laser-marked plastics were developed. These incorporate [[silicate]] or other materials which [[Conduction (heat)|conduct]] excess heat away from the material before it can deform. Outer [[laminate]]s of this material vaporise easily to expose different coloured material below.

Other plastics may be successfully engraved, but orderly experimentation on a sample piece is recommended. [[Bakelite]] is said to be easily laser-engraved; some hard engineering plastics work well. Expanded plastics, [[foam]]s and [[Polyvinyl chloride|vinyl]]s, however, are generally candidates for routing rather than laser engraving.  Plastics with a chlorine content (such as [[Polyvinyl chloride|vinyl]], PVC) produce corrosive chlorine gas when lasered, which combines with Hydrogen in the air to produce vaporised [[hydrochloric acid]] which can damage a laser engraving system. [[polyurethane|Urethane]] and [[silicone]] plastics usually do not work well, unless it is a formulation filled with [[cellulose]], stone or some other stable [[Thermal insulation|insulator]] material.

[[Kevlar]] can be laser-engraved and laser-cut. However, Kevlar does give off extremely hazardous fumes ([[cyanide]] gas) when it is vaporised.