Washing and Curing Resin Prints: The Complete Process
Wash in IPA or dedicated wash solution for 2–4 minutes, allow to air dry fully (10–15 minutes minimum), then UV cure for 2–5 minutes for small parts or 5–10 minutes for large parts. Do not cure without washing first — trapped uncured resin will polymerise and cause surface defects.
Resin parts come off the build plate in a partially-cured state coated in liquid resin. The wash and cure process removes the liquid resin and completes the polymerisation that gives the part its final mechanical properties. Cutting corners on either step produces tacky surfaces, weakened parts, and compromised dimensional accuracy.
Safety First
Uncured resin is a skin and respiratory irritant. Wear nitrile gloves throughout the wash and cure process. Work in a ventilated space. Do not pour waste resin or IPA down the drain — it must be disposed of responsibly. Cure waste resin under UV to solidify it before disposal.
Step 1: Remove from Build Plate
Use the removal tool to lever the print from the FEP plate gently. If it is adhering strongly, check that the bottom exposure was not excessive. Remove directly into the wash solution to minimise uncured resin contact with surfaces.
Step 2: Wash
Two wash approaches are common:
IPA (Isopropyl Alcohol) 99%: Most effective and widely available. Place the part in a sealed container of IPA and agitate — either by shaking manually or using an automated wash station. Wash time: 2–4 minutes for small parts, 4–6 minutes for large or complex parts. IPA becomes saturated with resin over time — replace when it becomes visibly cloudy or yellowish.
Dedicated wash solution: Manufacturers including Monocure 3D produce dedicated washing solutions that are less aggressive than IPA on some resin formulations. Follow the manufacturer's specific instructions for wash time and reuse limits.
Do not over-wash. Excessive time in IPA can cause some resins to absorb the solvent, leading to swelling and dimensional change. 2–4 minutes is adequate for most parts.
Step 3: Air Dry
This step is frequently skipped and is consistently the cause of tacky or frosted surface finishes. The part must be completely dry before UV curing. Any IPA or wash solution trapped on the surface will prevent proper cure of the outer layer.
Air dry for 10–15 minutes minimum, or use a compressed air blow-down to accelerate drying in cavities and undercuts. The part should feel completely dry with no visible liquid.
Step 4: UV Cure
Post-curing under UV completes the polymerisation and achieves the material's rated mechanical properties. Under-cured parts are weaker and more brittle than properly cured parts.
| Part Size | Recommended Cure Time (405nm, ~36W) |
|---|---|
| Small (< 50mm) | 2–3 minutes per side |
| Medium (50–150mm) | 3–5 minutes per side |
| Large (> 150mm) | 5–8 minutes per side |
| Engineering / Tough resin | +50% above standard times |
Cure in a UV station with a rotating turntable to ensure even exposure. If you do not have a UV station, direct sunlight works (clear/sunny day, 5–15 minutes) but is less consistent.
Over-Curing
Over-curing causes brittleness and yellowing, particularly in clear resins. The surface becomes dull and loses the semi-gloss finish of properly cured resin. If your parts are yellowing quickly or becoming very brittle, reduce cure time.
Support Removal Timing
Supports are easier to remove after washing (before full UV curing) when the part is still slightly flexible. Use this window for complex support removal — remove supports after washing, then cure.
Download PDF reference
Print-ready A4 landscape summary — keep it at the printer for quick reference.
Download PDFNeed help with your project?
Get in touch for a consultation, print quote, or just to talk through material selection.