Resin: the part stays sticky after printing

Likely causes

In order: the most frequent cause comes first.

1. 01No post-curing: the resin on the surface remains unpolymerised
2. 02Insufficient washing, or washing in alcohol already saturated with resin
3. 03Liquid resin trapped inside a hollowed part with no drain holes
4. 04Curing in a cold room or with a UV lamp of the wrong wavelength
5. 05Over-washing, which at the other extreme produces micro-cracks from prolonged alcohol exposure

How to fix it

Apply one fix at a time and reprint the same test part. Changing three settings at once tells you nothing about which one worked.

1. 01

   Complete the wash, dry, cure cycle

   Easy

   A freshly printed part is soft and sticky by definition: it retains unpolymerised resin on its surface. The full process is wash in isopropyl alcohol or water depending on the resin, dry thoroughly and cure under ultraviolet light. Without post-curing the part will never stop being tacky.

2. 02

   Do not wash for more than ten minutes in alcohol

   Easy

   Prusa warns against washing for more than ten minutes in isopropyl alcohol, because prolonged exposure causes micro-cracks on the surface. If ten minutes leaves the part still tacky, the problem is not the time but saturated alcohol: change it.

3. 03

   Dry the part before curing it

   Easy

   Alcohol or water left on the surface interferes with curing and leaves matte, soft patches. Dry it with air, a blower or by letting it drip, and only then send it to the UV lamp. Prusa describes the cycle as washing, drying with hot air and curing with ultraviolet light.

4. 04

   Check that a hollowed part has drain holes

   Medium

   A hollowed part with no holes retains liquid resin inside that seeps out through the pores over days and makes the surface tacky again. The fix is redesigning with two holes of at least 3 mm, one in and one out, in the least visible area.

How to prevent it

• —Always handle the part with nitrile gloves until it is post-cured
• —Change the wash alcohol when it looks cloudy, not when it has stopped working
• —Hollow with drain holes from the design stage, not afterwards
• —Cure in sunlight or with a 405 nm UV lamp, not with any lamp to hand

Sources

1. [1]Using the CW1 - Washing | Prusa Knowledge BasePrusa Research · Manufacturer · accessed July 27, 2026
2. [2]Resins | Prusa Knowledge BasePrusa Research · Manufacturer · accessed July 27, 2026