Surface Topography and Finishing of Vat-Printed Photopolymers: Roughness Metrology, Orientation, Stair-Stepping, Polishing and Functional Transfer

Vat-photopolymerised parts are often described as having smooth or high-quality surfaces, yet published studies show that the realised topography depends on both process physics and measurement method. DLP formulation can change feature size and stair-stepping; LCD projection discontinuities can generate lateral texture; build direction alters roughness; post-curing and polishing change the measured surface state; and finishing can simultaneously change roughness, gloss and other functional outputs. This Engineering Review develops a state-based qualification framework for surface topography of SLA, DLP and LCD/MSLA photopolymers. It distinguishes profile from areal parameters, separates form/waviness/texture scales, requires explicit filter and instrument reporting, and treats orientation and surface identity as experimental variables rather than nuisance metadata. Polishing and chemical or abrasive smoothing are treated as manufacturing operations that create a new surface state, not as universal corrections. 3Dresyns Cleaning Paste CP1 Bio, Cleaning Paste CA1 Bio, Cleaning Fluid WS1 and ophthalmic material collections are included only as manufacturer implementation examples. Their commercial descriptions do not establish a universal roughness reduction or functional surface specification.