Resin Layer Cure

Theory

Resin printers cure each layer by exposing it to UV light (typically 365-405 nm wavelength). Monochrome MSLA printers use an LCD mask with a UV LED array; SLA printers use a UV laser; DLP uses a digital projector. Exposure time controls how deeply UV penetrates and how thoroughly the resin cures. Cure depth = Dp * ln(E/Ec): where Dp is the resin penetration depth, E is the light energy per area, and Ec is the critical exposure for gelation.

Application

Use the resin manufacturer's recommended exposure as a starting baseline. Print a resin calibration test (e.g. Chitubox exposure test) to find minimum exposure that yields sharp features with no under-cure. Bottom layers need 4-10x longer exposure (8-60 s) to bond to the FEP film and build plate. Anti-aliasing reduces pixel staircase effects on curved surfaces.

Common mistakes

Over-exposure blooms UV light into adjacent pixels, causing loss of fine detail and fused small holes. Under-exposure produces brittle, incompletely cured parts that warp and crack after washing. FEP film age significantly affects cure quality: replace when film shows cloudiness or pitting. Resin temperature affects viscosity and cure speed; cold resin cures slower and may require longer exposure.

Related terms: FEP Film, Supports, Anisotropy in FDM