Prusament's New Resin Is Safer and Faster — With One Catch

Prusa’s new photopolymer resin removes three chemicals that routinely appear in standard hobby resins — Bisphenol A, TPO, and ACMO — while also reducing layer exposure times and improving impact resistance. Those are meaningful improvements. The viscosity increase creates a workflow consideration that the headline specs don’t immediately reveal.

What Changed in Resin Model+

Prusament Resin Model+ is positioned as a next-generation upgrade to the original Prusament Model Resin, targeting improved health safety alongside better mechanical properties. The chemical reformulation removes Bisphenol A (an endocrine disruptor that appears in many standard resins), TPO (a photoinitiator with known sensitization risk at repeated exposure), and ACMO (a reactive diluent with respiratory and skin hazard profiles). The pine scent is a deliberate indicator of the cleaner formulation — an unusual but functional communication choice.

Exposure times are substantially faster: 2–2.6 seconds per layer at 0.05mm layer height, with a 16-second base layer. For Prusa SL1 and SL1S users, that’s a meaningful throughput improvement over the previous Model Resin. Mechanical properties also improve: better impact resistance, enhanced ductility, and significantly reduced pigment sedimentation in light-colored variants — a persistent problem in multi-color or light resin workflows where settling creates inconsistent batches.

The bio-based content is 14%, contributing to the safer profile. Shrinkage is 6–7%, on the lower end for photopolymers — an important factor for dimensional accuracy in precision parts or interlocking assemblies. Price is $71.99 per 1kg canister ($73.99 EUR), broadly consistent with premium hobby resins at this performance tier.

The Viscosity Tradeoff

Here’s what the spec sheet downplays: Resin Model+ has a viscosity of 300–400 mPas — notably higher than most hobby resins. High viscosity slows the peel cycle during printing and requires longer pre-exposure wait times between layers to allow the resin to flow back and level fully. In practice, this partially offsets the faster exposure times in terms of real-world print speed.

This isn’t a reason to avoid the resin — the health and mechanical property improvements are genuine — but it’s a calibration consideration. Prusa SL1S users may need to adjust lift speed and wait time settings to account for the higher viscosity, particularly on large cross-sectional prints where the peel force and reflow requirements are greatest. Prusa’s recommended settings in PrusaSlicer should be treated as a starting point rather than a final configuration.

Source: Prusa Blog

Content created with AI assistance and reviewed for accuracy.