Resin (MSLA) Printing Basics

Resin (MSLA/LCD) printers cure liquid photopolymer with UV light, one whole layer at a time, instead of squeezing melted plastic through a nozzle. The payoff is resolution: crisp miniatures, jewelry, and fine detail that FDM can't match.

The trade-offs are a smaller build volume, a messier, more hands-on workflow, and real chemical-safety requirements. Resin is a complement to FDM, not a replacement.

Liquid resin is a skin irritant and sensitizer — repeated exposure can cause lasting allergic reactions. Treat it like a workshop chemical:

• Always wear nitrile gloves and eye protection
• Work in a well-ventilated space; many resins give off fumes
• Never let resin touch bare skin; wash spills immediately
• Cure all waste resin solid (sunlight/UV) before disposal, and never pour resin or IPA down a drain
• Keep resin away from children and pets

Resin parts come off the printer wet and only partially cured. Every print needs post-processing:

1. Print — the part builds upside-down on the plate
2. Wash — rinse off sticky uncured resin in isopropyl alcohol (or water for water-washable resin)
3. Remove supports — easier while the part is still slightly soft
4. Cure — finish hardening under UV (a curing station or sunlight)

Under-washed or under-cured parts stay tacky, brittle, or keep leaching resin.

The main setting to dial in is exposure time — how long each layer sees UV. Too little and layers don't stick or fine details wash away; too much and details bloat and small gaps fill in. Print a standard exposure-test model to find the sweet spot for your specific resin and screen.

Resin parts are almost always printed at an angle on heavy supports — this reduces suction forces, avoids huge flat layers, and keeps detail faces support-free. Modern slicers (Lychee, Chitubox) auto-generate supports, but check that every island has one.