Resin 3D Print Post Processing: Wash, Dry, and Cure an MSLA Part

Why post processing makes or breaks a resin part

Unlike an FDM part that comes off the printer already solid, an MSLA resin print is only halfway done when the machine stops. UV light from the screen cured the material just enough to hold its shape, but the surface is still coated in a film of liquid resin that was never exposed, and the inside of thicker parts often hasn't reached full hardness yet. That gap between a print that merely holds its shape and a part that has its final mechanical properties is easy to underestimate the first time you switch from FDM to resin.

That post-processing cycle, washing followed by curing, is what largely determines the part's mechanical strength, dimensional accuracy, and surface finish. For background on why a resin printer works so differently from an FDM machine, our how a 3D printer works page covers the LCD screen and UV LED array in detail.

Popping the part off the plate and clearing excess resin

Start by prying the part off the build plate, usually with a metal or plastic scraper slid under the raft or support base. Do this over the vat or a dedicated container to catch dripping resin, not over a sink drain.

Before washing, let the part drip for a few minutes with the plate turned over, so any still-liquid resin falls back into the vat instead of contaminating the wash bath and wearing out the solvent faster. Nitrile gloves are a must from this point on, since uncured resin is listed as a skin irritant on manufacturer safety data sheets.

Washing the part: IPA, an alcohol-free solution, or water-washable resin

Isopropyl alcohol (IPA) at 90% or higher is still the most common wash medium: the part gets submerged and agitated, either by hand or in an automated wash station. Per Anycubic's cleaning guide, a small part typically washes in a couple of minutes while a large part can take ten to twenty minutes by hand, and soaking well past that risks swelling or cracking the material.

Alcohol-free cleaning solutions, tripropylene glycol methyl ether being a common one, exist for workshops that want to avoid a flammable solvent; Anycubic recommends capping soak time at roughly three to five minutes depending on part thickness. Water-washable resins also exist, formulated to clean up without any solvent at all, though that convenience generally comes with a longer wash time, on the order of ten minutes per the same guide. None of these numbers are hard rules; they're starting points from the manufacturers, and the part itself, not the clock, is the better guide to when it's clean.

Drying and removing supports: which comes first?

Once washed, the part needs to dry completely before anything else: compressed air speeds this up on recessed areas where solvent tends to pool, followed by air-drying out of direct light. Per Formlabs, a part that still carries solvent when it goes into a UV curing chamber can let that solvent evaporate and re-condense inside the machine, clouding its reflective interior surfaces.

Support removal can happen before or after curing: pulled off before curing, the material is still slightly pliable and comes away more easily, at some risk of distorting a thin feature; removed after, the part is harder and the support nubs snap off cleaner, though it takes a steadier hand to avoid marking the surface.

UV curing: the station, cure time, and the risk of over-curing

Final curing happens under UV light, either in a dedicated station with LEDs and usually a rotating plate for even exposure, or in direct sunlight for a rougher result. Per Anycubic's post-processing guide, a full cure cycle generally runs at least around thirty minutes, with the part rotated through multiple angles so light reaches every face.

Leaving a part under UV longer does not make it indefinitely stronger: past the point needed to hit target mechanical properties, over-curing can leave the material more brittle and shift its color, particularly on clear or translucent resins. Formlabs also recommends placing the part in the machine right as preheating starts rather than waiting for it to reach temperature, since a sudden thermal shock can crack the part.

Finishing: sanding and priming before paint

Once cured, a part can be sanded to smooth out support marks and layer lines, starting with a medium grit and working finer. A rattle-can primer then evens out the surface and reveals any remaining flaws before paint, a step common in the miniatures and cosplay space. Wet sanding with a fine grit and some water cuts down on dust and gives a smoother result than sanding dry.

These finishing steps are cosmetic: they do not change the part's mechanical strength and are no substitute for a proper wash-and-cure cycle. If the goal is a functional part rather than a display piece, get the washing and curing right before worrying about sanding.

Handling resin waste and protective gear

Liquid resin and used solvent should never go straight down a drain or into regular household trash. The generally recommended practice is to expose leftover resin, soaked rags, and the residue in the wash bath to UV light or sunlight until it cures fully solid; once it's hard and no longer tacky, it becomes inert and can follow whatever hazardous or special waste stream applies where you live, since rules vary by state and municipality. Small studios sometimes pool leftover resin from several prints into one container specifically to cure it in a single batch, rather than handling a dozen small amounts separately.

Nitrile gloves, eye protection, and a ventilated workspace are recommended by manufacturers throughout the process, since liquid resin and its vapors can irritate skin, eyes, and airways. A resin workflow is easier to manage in an enclosure or a well-ventilated room than in shared living space.

Sources and limits

• Elegoo — How to Do Resin 3D Printing, Beginner's Guide
• Anycubic — How to Wash and Clean 3D Resin Prints
• Anycubic — Mastering Post-Processing: 5 Steps to Post Process Resin Prints
• Formlabs Support — Best Practices for Post-Curing Prints

We organize manufacturer and community documentation; we have not measured these products ourselves. The manual for your exact model takes precedence over general guidance.