Similar to stereolithography in that parts are made with a photosensitive resin, the Polyjet difference is in how the resin is applied and cured to build the part. The super thin layer thickness results in parts that are very accurate with a very smooth surface finish.

SLA is an additive process utilizing a vat of liquid UV curable photo polymer "resin" and a UV laser to build parts a layer at a time. On each layer, the laser traces a part cross-section pattern on the surface of the liquid resin. Exposure to the UV laser light cures, or solidifies the pattern traced on the resin and adheres it to the layer below.

This technology allows for the production of highly accurate parts with superior surface quality.  The envisionTEC SI 500 is a high-speed, liquid resin that produces flexible, high-impact-strength, and accurate parts with a wide processing latitude and excellent tolerance to a wide temperature and humidity range during and after build. This material is especially useful in functional applications where extreme flexibility and impact strength are critical requirements, e.g. automobile panels, electronic enclosures, medical products, snap-fit parts, packaging, and plastic bottles.