Washing and curing resin prints

Why does a resin print still need work after it comes off the printer?

A part straight off the build plate has only been shaped by the printer; it has not finished chemically hardening, and its outer surface is coated in a layer of resin that was never exposed to UV light during printing. That coating is fully uncured and remains a skin sensitiser until it is removed and the part is properly cured.

Washing removes the uncured surface layer and curing finishes hardening the resin all the way through. Treating a freshly printed part as "done" before both steps is the most common way resin printers end up with sticky, weak or unsafe parts.

What is actually happening when I wash a print in isopropyl alcohol?

Isopropyl alcohol dissolves the thin, uncured resin film clinging to the surface of the part without meaningfully attacking the resin that has already cured underneath. Agitating the part in IPA, whether by hand or in a wash station, speeds this up by constantly bringing fresh alcohol into contact with the surface.

A part is adequately washed once the surface no longer feels tacky or slick; a genuinely clean surface should feel dry to a gloved touch. Under-washing leaves sensitizing resin on the surface, and over-washing for extended periods can dull fine surface detail on some resins.

Why does curing still matter after the part is already washed and dry?

Washing only removes uncured resin from the surface; it does not finish the chemical reaction inside the part. A washed-but-uncured part is typically still soft, slightly flexible and dimensionally not at final strength, and any washed part will still have areas that have not been fully exposed to UV, particularly at the surface.

Curing under UV light, either from a dedicated cure station such as the ANYCUBIC Wash and Cure Machine 3.0 or from sunlight, completes the hardening reaction so the part reaches its final strength, stiffness and dimensional accuracy.

Do I need to wear gloves during washing if the part already went through IPA?

Yes. A part coming out of the wash step is cleaner than it was straight off the printer, but it has not been cured yet, and any resin still dissolved on the surface or in surface texture remains a skin sensitiser until curing is complete. Keep nitrile gloves on through the entire wash-then-cure sequence, not just during the printing and initial handling stages.

Sensitization from resin exposure is cumulative, so the risk from a "mostly clean" part handled barehanded repeatedly over months is a real one, not a hypothetical.

What is the correct way to get rid of the isopropyl alcohol once it is full of dissolved resin?

Used wash IPA is not a drain matter. It contains dissolved uncured resin, and pouring it down a sink sends that resin into the wastewater system. Instead, pour the used IPA into a clear, sealable container and leave it in direct sunlight or under a UV light source until the dissolved resin cures and drops out as solid material.

Once the resin has fully separated and hardened, filter the solids out, let them cure completely if they are not already hard, and throw them away as solid waste. The remaining IPA is often clean enough to reuse for another wash or two before it needs replacing outright.

How do I know when a part is actually finished versus just dry to the touch?

A part that only feels dry has passed the wash stage but may not have completed curing. Fully cured parts are noticeably harder, resist a fingernail scratch far better, and no longer have any give when you flex a thin section. Comparing a suspect part against one you know is fully cured is the simplest gut check available without lab equipment.

If a part still feels slightly rubbery or tacky at edges or in recessed areas after a normal cure cycle, give it additional cure time, since shaded or recessed surfaces receive less direct UV exposure than flat, exposed faces.

Safety