Below is data about the optical properties of selected Formlabs SLA resins. Use this data along with the information in Choosing the right material and the technical data sheet (TDS) for your selected material to pick a resin and evaluate your printed parts. If data for your material is not available, choose the closest comparable material and interpolate or extrapolate as necessary. For other requests, reach out to Formlabs Support or your sales representative.

The transmission spectra and refractive index (RI) of Clear Resin V4 has been thoroughly studied and published. For more information, see Fabrication of optical components using a consumer-grade lithographic printer.

The average refractive index of Clear Resin V4 is approximately 1.51. Below is a summary of the refractive index of Clear Resin V4 at different wavelengths.

Below is a summary of the average refractive indices of a selection of resins, measured across a broad band of wavelengths. Note that part geometry and post-processing may impact refractive index.

Gloss testing measures the capacity of a surface to reflect light. A higher number indicates a reflective material, whereas a lower number indicates a matte surface. Testing was performed with a measurement angle of 60°. Part geometry and printing orientation may impact the gloss measurements. In general, parts printed in the X/Y direction (i.e., horizontal, laying down) are more glossy than parts printed oriented along the Z-axis (i.e., vertical, standing up).

Formlabs resin is not transparent to microwaves. If printed parts are microwaved, they heat rapidly and may experience thermal degradation. Formlabs does not recommend microwaving any resin-printed parts.

Most Formlabs resins exhibit high fluorescence under UV light, emitting a bluish glow. Black Resin and Dental SG Resin do not fluoresce.