How to Wash and Cure Resin Prints

A resin print is not finished when the printer stops. It comes off the plate covered in liquid resin and only partly hardened. Washing removes the wet resin, and curing with UV light hardens the part fully. This guide explains the order of steps, typical times from maker documentation, and the mistakes that cause sticky, cracked or yellow parts. If you are new to resin, read what is resin 3D printing first.

The steps at a glance

Step 1: Remove the print safely

When the print finishes, open the printer lid and place a tray around the resin vat to catch drips. Prusa's instructions say to wear gloves when removing the printing platform. Let the resin drip off the part for a short while before moving it, and use paper towels to catch the drips. Treat everything that touches liquid resin as contaminated.

Step 2: Wash the print

The wash removes uncured resin. Most standard resins are washed in isopropyl alcohol (IPA), which Prusa calls a volatile flammable liquid. Keep it away from heat and ignition sources. Water-washable resins are rinsed in water instead, and Elegoo markets its water-washable range as rinse-under-water.

Prusa's own process for its CW1 machine works like this:

1. Fill the tank with isopropyl alcohol, leaving the surface about 2 to 3 cm (about 1 in.) below the edge.
2. Submerge the print, either on the platform or removed and placed in the basket.
3. Run the wash for 3 minutes, which is the default.
4. Remove the object wearing protective gloves.

Do not leave prints in IPA for long. Prusa recommends against washing objects in IPA for more than 10 minutes, because tiny cracks may appear on the surface, even after more than 24 hours. A longer wash is not a better wash.

If you do not have a wash station, the same principle applies: the part needs a bath that removes liquid resin without a long soak. Follow your resin's datasheet for the solvent and the time.

Step 3: Dry the print

Prusa's guide says to dry the washed part with a paper towel before curing. After that, the CW1 has a drying mode that, by default, runs for 3 minutes. Check your resin's guidance on how dry the part should be before curing. Used paper towels and solvent are waste; dispose of them as the SDS and your local rules require.

Step 4: Cure with UV light

Curing finishes the chemical reaction. Prusa's CW1 default curing time is 3 minutes. Elegoo's Wash and Cure Station 3.0 lets you set the wash and cure duration up to a maximum of 30 minutes. A cheap alternative is sunlight, since resin cures in UV light, including sunlight. That takes longer and is less consistent. A reply in the comments on Prusa's curing page says a part can be left outside, but that it takes more time.

Three practical rules from the maker documentation:

• Expose the part evenly. Prusa notes that some surfaces, such as the base of a model, can remain uncured on a rotating platform. Flip the part during curing, and remember that flipping splits the time: a 6 minute cure with one flip gives each face 3 minutes.
• Do not over-cure. Prusa says yellowing becomes more significant with long post-curing, and that after 60 minutes a model can stay yellowish. For its model resins it suggests starting with shorter times, at least 3 minutes.
• Use the resin's own advice. Different colors and materials need different times.

Step 5: Remove supports and finish

Removing supports comes after washing. Whether to cut them off before or after curing depends on the resin, so follow the resin maker's guidance, and clean the part again if it picks up resin or dust.

Troubleshooting

If the print itself failed, see fixing failed resin prints. To pick a printer and the extras that go with it, see best resin 3D printers.

Quick check that the cure worked

A fully cured part feels dry and not tacky on every face, including the base. If one face is still tacky, cure again with that face towards the light. Do not keep curing indefinitely: if the part is dry, stop.