UV Resin Cure Time per Layer

UV resin layer cure time in SLA and DLP printers

On masked SLA (MSLA) and DLP machines, almost all of the print time comes down to what each layer needs to cure: t_total ≈ n_layers · (t_cure + t_lift). Run a standard photopolymer on a typical 405 nm LCD at 8 W/cm² and a 50 µm layer sets in roughly 1–3 s. The bottom layers, the first 4–8, get 5–10× that for adhesion. Then there's the lift cycle that peels, raises and settles the plate, which tacks on another 4–8 s a layer and quietly becomes the bottleneck once your part gets tall.

Once the print comes off, you wash it (IPA or tripropylene glycol) and post-cure it under UV light for 5–15 min in a chamber like the Anycubic Wash & Cure, Elegoo Mercury Plus or Formlabs Form Cure. How much exposure you actually need comes down to the resin’s photoinitiator, which absorbs at 365, 385 or 405 nm. That's why engineering resins from Phrozen, Siraya Tech, Anycubic, Elegoo and Formlabs come with their own cure tables.

Applications

Think dental aligners and surgical guides, miniatures for tabletop games, investment-casting masters for jewelry, prototype electronics enclosures, hearing-aid shells, and functional parts in tough or ABS-like resin. Once you know the cure time per layer, the trade-off becomes clear: 25 µm layers when jewelry detail matters, 100 µm when you're churning out minis and want speed over fidelity.

FAQ

How do I find the right exposure? Run a calibration matrix like Cones of Calibration or RERF. It walks you through a range of cure times, and you keep the shortest one that still resolves your smallest features cleanly without blowing out the tolerances.

Why are bottom layers so much longer? Their job is to grip the build plate, so the printer hits them with 30–60 s instead of the usual 1–3 s. Skimp on the count and the print pops off the plate mid-job.

Is post-cure really necessary? Yes. A part straight off the printer is only partway polymerized. Skip the post-cure under 405 nm UV (or sunlight) and it stays tacky, weak and brittle, and it keeps off-gassing uncured monomer.