A resin is a liquid or highly viscous mixture of chemical compounds that can be turned into polymers. Photosensitive resins are used in 3D-printing, where they are converted into a solid state after reacting to an outside stimulus, usually light or heat.
In the SLA and DLP 3D printing methods, specifically, photosensitive resins are used. The resins consist of a mixture of monomers, oligomers and photoinitiator, which react to the light and form strong bonds. The so-called crosslinking reaction turns the liquid or viscous resin into a solid polymer.
Benefits to 3D printing with resins include projects with better resolutions, fine detail, and smoothness. Because UV light is projected onto precise areas of the liquid resin at the time of printing, a very fine resolution can be achieved. This makes resin a fine choice for jewelry, electrical components, and detailed mechanical prototyping.
Printing is also very quick compared to extrusion methods with materials like PLA or SBA filament used in an FDM 3D printing machine. Resin objects can be hardened at the point the light hits them instead of waiting for a nozzle to move around at the various points on a filament build. Letting the light do the work saves significant time in complicated or large area-builds.
Resin also creates durable and robust end products with better surface appearances. With the advancement of resin mix-ins, like ceramic and metal, even more finishes and textures can be achieved, as well. Instead of applying paint or enamel to create a metallic look, the metal powder can be mixed in and be distributed evenly through the build.
Because photosensitive resins rely on a photoreaction to reach their final form, care must be taken to store and mix resins appropriately. Printing with resin also requires some additional steps in finishing, such as rinsing away residue or performing a final light treatment for increased strength.
Because of the versatility and durable resin offers, it’s a preferred choice for professional 3D printing projects and engineering builds.
The exact type of resin you choose for your project will depend on the desired traits you want in your 3D build, as well as the type of printer you are using.