Lab Directions (Experts Only)

Danger

This page is intended for trained professionals only. Resin mixing is hazardous and must only be performed by qualified personnel in a laboratory fume hood. If you are not equipped to mix photopolymer chemistry safely, do not attempt this; instead, purchase the pre-mixed resin (see Overview).

The OpenCAL resin is a UDMA-based photopolymer tuned for Computed Axial Lithography. This page covers the resin recipe, where to source each component, and the lab procedure used to mix it.

Danger

Resin mixing is hazardous and must only be performed by trained professionals in a laboratory fume hood.

The components are reactive methacrylate monomers and amines that are skin/eye irritants, sensitizers, and harmful if inhaled or ingested. Before handling anything:

  • Work only inside a certified chemical fume hood.

  • Wear appropriate PPE: nitrile gloves, safety goggles, and a lab coat.

  • Read and follow the Safety Data Sheet (SDS) for every chemical below.

  • Never mix outside of a properly equipped lab. This is not a home or hobbyist procedure.

Resin Recipe

The final recipe, by concentration in the UDMA base resin:

Component

Concentration

Role

CQ (camphorquinone)

2.5 mM

Photoinitiator

EDAB (ethyl 4-dimethylaminobenzoate)

5 mM

Co-initiator

MDEA (N-methyldiethanolamine)

200 mM

Co-initiator (oxygen scavenger)

UDMA (urethane dimethacrylate)

Base resin

Monomer

Suppliers

Component

Size

Link

CQ (camphorquinone)

5 g

TCI C0014

EDAB

25 g

TCI D1744

MDEA

250 mL

Sigma-Aldrich 471828

UDMA (Esstech X-850)

4 kg

Esstech X-850

Mixing Procedure

This is the procedure currently used in our lab. It is constrained by lab-scale equipment (small hot plates and magnetic stir bars rather than industrial mixers), so the mixing times below are conservative and could be shortened significantly with better equipment.

  1. Heat the UDMA base resin to 60 °C in a water bath, in a sealed container.

  2. Add the CQ and EDAB to the resin. Mix on a stir plate at 70 °C and 200 rpm. Wait approximately 12 hours, until fully dissolved.

  3. Turn the temperature down to 40 °C.

  4. Add the MDEA. Wait 1–2 days, until fully mixed.

Important

Two things are critical to a good batch:

  • Do not heat the resin while mixing in the MDEA. Cool to 40 °C first.

  • MDEA readily reacts with atmospheric oxygen and degrades itself. Always mix in a sealed or semi-sealed container to limit air exposure.