Also called SLA, stereolithography was invented in the early 1980s and entered the public consciousness as consumer and prosumer desktop 3D printing became popular in the early 2010s.
The SLA process uses a liquid resin that cures or solidifies when a laser of UV light is applied to the resin. This type of material, a thermoset, undergoes a chemical reaction when exposed to heat or UV light, hardening the liquid resin into a solid. Resins can come in assorted colors and are loaded into bottles that can then be added to the tank of the stereolithographic 3D printer. Once loaded, the printer can utilize the various colored resins to print.
As the printer applies liquid resin to an existing layer of the structure, the device shines a beam of UV light from a projector or laser. The resin’s chemical properties react to specific wavelengths of light emitted by the light, which cause the resin’s monomers and oligomers to join in chains, forming polymers (the basis of plastic) and hardening the material on the build surface layer.
Depending on the type of resin used, the final product’s physical properties can vary to suit the part’s end use better. These variations can include color, flexibility, durability, and weight.