OpenCAL Resin – Clear 0.9L

Prusa Continues to Support Open Source Projects Open source is where Prusa began. Josef Prusa's first printers came out of the RepRap community, and Prusa Research still shares how it builds its machines so others can learn, modify and create. Printer firmware is published on GitHub, PrusaSlicer is free and open source, printable parts are released on Printables, and newer projects like the OpenPrintTag smart-spool standard carry the same approach into materials. Distributing OpenCAL Resin is just part of our continued support: it gives the open-source volumetric printing community a ready-to-use material from a name they already trust. Read more about open source at Prusa Research. OpenCAL Resin – Clear 0.9L UDMA-based photopolymer for Computed Axial Lithography (CAL) • Volumetric 3D printing • Distributed by Prusa Research OpenCAL Resin is a UDMA-based photopolymer made for Computed Axial Lithography (CAL), a volumetric 3D printing process. Light patterns are projected into a rotating vial of resin, and wherever enough light builds up, the part forms all at once. There are no layers and no supports, and a print takes minutes. The resin was developed as open source by the team at UC Berkeley that invented CAL. Formlabs mixes and manufactures it to the official OpenCAL formulation, and Prusa Research distributes it, so every bottle has consistent, lab-grade chemistry with no mixing on your part. It cures to a hard, glassy, very low-color material with a glass transition temperature of 140 °C. Why Choose OpenCAL Resin? True Volumetric Printing Formulated specifically for the way CAL cures resin, not a repackaged SLA resin. Its camphorquinone (CQ) visible-light initiator system gives a crisp boundary between the cured part and the liquid resin around it. High-Speed Printing Prints inch-scale parts in minutes. The whole part volume receives light at the same time, so print time depends very little on part height. No Layers, No Supports Parts form while suspended in the surrounding resin, so there are no layer lines to sand and no supports to remove. Delicate and overhanging shapes print cleanly. Consistent Quality Formlabs mixes and manufactures the resin to the official open-source OpenCAL formulation under professional process control. Every bottle has consistent, lab-grade chemistry, and you never handle raw chemicals. Fully Open Source The complete formulation, suppliers and mixing procedure are published in the OpenCAL documentation, with no proprietary chemistry and no vendor lock-in. The resin is validated on the OpenCAL V2 platform with Tomo/VAMToolbox, the free and open-source print-preparation software. Whole Parts in Minutes: How CAL Works UC Berkeley invented CAL in 2017, and it works like a CT scan in reverse. Open-source software (Tomo/VAMToolbox) calculates a sequence of images and projects them through a rotating vial of resin, so the whole part volume receives light at the same time. Only the areas that make up your part get enough light to harden. The rest stays liquid and pours away. Inch-scale objects form in minutes as the vial rotates. No layer lines: surfaces come out of the vial smooth. No support structures: delicate and overhanging shapes print cleanly. The uncured resin drains away and can be reused, which cuts waste. Open-Source Chemistry, Professional Production OpenCAL Resin is formulated specifically for tomographic, volumetric printing: UDMA (urethane dimethacrylate) base: chosen for the viscosity and optical clarity that volumetric printing needs. CQ/EDAB photoinitiator system: reacts to visible (blue) projector light, so no UV laser is needed. MDEA oxygen-scavenging co-initiator: sharpens the curing threshold so part edges come out accurate. You don't need to mix it yourself: Formlabs mixes and manufactures the resin to the OpenCAL formulation under professional process control. Prusa Research distributes the finished resin, so it's easy to buy. We strongly recommend buying the pre-mixed resin. Mixing from raw chemicals should only be done by trained professionals in a laboratory. Basic Attributes + Prints inch-scale parts in minutes; print time depends very little on part height + No layer lines and no support structures + Hard, glassy, very low-color, non-yellowing cured material (Tg 140 °C) + Uncured resin can be drained and reused + Fully open-source, published formulation - Requires a CAL/VAM system (e.g., OpenCAL V2); not compatible with standard layer-by-layer SLA/MSLA printers - Sensitive to ambient light; handle under dim room light and store in the dark - Higher viscosity (9,000 cps at 50 °C); printing goes better if you warm it first Tips & Tricks For Beginners Everything you need to know before printing Work under dim light. The CQ initiator system reacts to visible blue light as well as UV. Keep containers capped and never expose the resin to sunlight. Sunlight makes it cure quickly and uncontrollably, and the resin can harden inside its container. Prepare prints with Tomo/VAMToolbox. This free, open-source print-preparation software calculates the projection sequence for your part, and it has been validated with this resin on the OpenCAL V2 platform. Reuse the uncured resin. After a print, pour the surrounding liquid resin back into a capped, opaque container to use on future prints and cut down on waste. The OpenCAL printing workflow recommends letting reused resin sit for about 24 hours before the next print so its oxygen level can settle again. Technical Parameters Volume 0.9 liter Process Computed Axial Lithography (CAL) / Volumetric Additive Manufacturing (VAM) Light source Visible (blue) light projection with CQ photoinitiator system Compatible hardware OpenCAL V2 and other CAL/VAM systems Print-prep software Tomo / VAMToolbox (free, open source) Base chemistry Urethane dimethacrylate (UDMA), difunctional Appearance Clear, very low-color liquid Odor Characteristic methacrylate Inhibitor BHT, 115 ppm Storage Cool, dark place; container capped; never in sunlight Manufactured by Formlabs, to the official OpenCAL open-source formulation Distributed by Prusa Research Material Properties (Cured) Property Metric¹ Imperial¹ Source Tensile strength 50 MPa 7,252 psi Esstech X-850 TDS² Elastic modulus 1,220 MPa 177 ksi Esstech X-850 TDS² Elongation 10% 10% Esstech X-850 TDS² Hardness 90 Shore D 90 Shore D Esstech X-850 TDS² Glass transition temp. (Tg) 140 °C 284 °F Esstech X-850 TDS² Volumetric shrinkage 7% 7% Esstech X-850 TDS² Viscosity 9,000 cps (50 °C) N/A Esstech X-850 TDS² ¹ Material properties can vary with part geometry, print parameters, delivered light dose, rinse and post-cure conditions. ² Typical properties of the cured X-850 UDMA base oligomer as published by Esstech. Properties of parts made from the finished resin may differ. Formulation (Published Open-Source Recipe) Concentrations in the UDMA base resin, from the published open-source recipe: Component Concentration Role UDMA, urethane dimethacrylate (Esstech X-850) Base resin Monomer CQ (camphorquinone) 2.5 mM Photoinitiator EDAB (ethyl 4-dimethylaminobenzoate) 5 mM Co-initiator MDEA (N-methyldiethanolamine) 200 mM Co-initiator (oxygen scavenger) Safety Precautions Always wear protective equipment. Wear nitrile gloves whenever you handle liquid resin or uncured (wet) parts. Follow the Safety Data Sheet (SDS). Keep the resin away from light. Photopolymer resin cures when exposed to light. Never expose it to sunlight: sunlight and other strong UV or blue light make it cure quickly and uncontrollably, which ruins the resin and can harden it inside its container. Work under dim room light. Store it correctly. Keep containers capped and store them in a cool, dark place. Downloads & Resources OpenCAL Documentation Materials Overview Printing Workflow OpenCAL on GitHub Join the OpenCAL Discord