Extruded acrylic is made by melting acrylic resins, and using the liquid to fill a die. The acrylic is then forced through rollers to give an even thickness and finish. It has a more constant thickness than cast acrylic, and it’s better suited to being vacuum shaped, bent and heated – but, it can be more susceptible to cracking in some situations. However, good quality extruded acrylic (such as Perspex) gives a very clean, smooth (flame-polished) edge when laser cut.
When extruded acrylic is laser cut or engraved, the surface does not change colour.
Cast acrylic is made by being cast (moulded) between two sheets of glass or metal. A spacer is used between the two sheets to set the thickness of the acrylic as it cools. The thickness of cast acrylic may change across a sheet. Cast acrylic is stronger than extruded acrylic and should not warp when heated. It resists impacts and scratching.
When cast acrylic is laser engraved, it turns a frosty white colour, so it is more suitable for plaques and trophies where the engraved surface should be visible through the acrylic.
Extruded for cutting, cast for engraving.
(See Technical Bulletin # 25 for more info and pics).