Activity 001: Resin Print Wash and Cure Lab¶

Activity ID: U2M4-ACT-001 Duration: 40 minutes Objective: Students will perform the complete wash and cure post-processing workflow on a freshly printed resin part, documenting each step and evaluating the results. Group Size: 2-3 students per station Materials Cost: ~$5-8 (resin part from previous module, IPA, UV cure electricity)

Overview¶

Students take a freshly printed (or instructor-prepared) green-state resin part through the complete wash and cure workflow. They time each stage, evaluate surface quality at each step, and compare green-state properties to fully-cured properties through hardness and flexibility tests.

Materials & Equipment Needed¶

Green-state resin print (from Module 3 activity or instructor-prepared)
Two IPA wash containers (labeled "DIRTY" and "CLEAN"), 500mL each, 90%+ IPA
Timer/stopwatch
UV post-curing station (405nm, with turntable)
Nitrile gloves (3-4 pairs per student)
UV-blocking safety glasses
Lab coat
Paper towels
Compressed air can (for drying crevices)
Shore D durometer (if available) or fingernail scratch test reference
Magnifying glass
Process documentation worksheet

Instructions & Procedure¶

Phase 1: Green State Evaluation (5 min) 1. Don PPE: lab coat, safety glasses, nitrile gloves 2. Examine the green-state part (still on the build platform or freshly removed): - Note the tacky surface feel (through gloved fingers) - Observe the glossy, wet appearance - Test flexibility: gently flex a thin section — note how much it bends - Perform fingernail scratch test: how easily does a scratch appear? - Record all observations on worksheet as "Green State" baseline

Phase 2: Two-Stage IPA Wash (10 min) 3. Start the timer 4. Submerge the part in the DIRTY IPA bath 5. Gently agitate by swirling the container or moving the part back and forth 6. Wash for exactly 3 minutes — observe the IPA becoming cloudy as it dissolves resin 7. Remove the part and transfer to the CLEAN IPA bath 8. Wash for exactly 3 minutes with gentle agitation 9. Remove the part and blot dry with paper towels 10. Use compressed air (short bursts, 15cm distance) to remove IPA from crevices, support marks, and concave features 11. Place the part on a clean paper towel and allow to air dry for 10 minutes 12. Record: total wash time, IPA cloudiness after wash, and surface feel (should now be smooth, not tacky)

Phase 3: Support Removal (5 min) 13. While the part is still in the green state (before UV curing): 14. Identify all support contact points 15. Using flush cutters, remove supports by cutting as close to the surface as possible 16. Count the number of supports removed and rate the ease of removal (easy/moderate/difficult) 17. Examine support marks — note their size and depth 18. Set aside any broken tips for later comparison

Phase 4: UV Post-Curing (10 min) 19. Verify the part is completely dry (no visible IPA, no wet feel) 20. Place the part in the UV curing station on the turntable 21. Set the timer for the recommended cure time (typically 8-10 min for standard resin) 22. Start the UV cure cycle 23. While curing, record predictions: how will the part's hardness, color, and flexibility change? 24. When the timer completes, remove the part (it may be warm — handle carefully) 25. Allow 2 minutes for cooling

Phase 5: Post-Cure Evaluation (10 min) 26. Repeat all green-state evaluations on the now fully-cured part: - Surface feel: should be hard, non-tacky - Flexibility test: same thin section — should be noticeably stiffer - Fingernail scratch test: should be harder to scratch - Color comparison: hold next to a photo of the green-state part (or a saved green-state sample) — note any color shift - Shore D hardness: if durometer available, measure and record 27. Compare support marks before and after curing — did curing make them more or less visible? 28. Complete the comparison table on the worksheet: Green State vs. Fully Cured for each property 29. Write a 2-3 sentence summary of the most significant changes observed

Discussion Points¶

How much harder did the part become after post-curing? Was the change obvious to the touch?
Did you observe any color shift? Was it subtle or dramatic?
Would the support marks have been easier or harder to remove after full curing?
If you had over-washed the part (15+ minutes in IPA), what would you expect to see?

Expected Outcomes¶

Green-state parts should be noticeably softer and more flexible than fully-cured parts
Surface should transition from tacky/glossy to hard/matte-to-satin after washing and curing
Support removal should be easy in the green state (before curing)
Students should observe a subtle color shift (typically slightly darker or more saturated)

Assessment Rubric¶

Criterion	Excellent (5)	Proficient (3)	Needs Improvement (1)
Wash Procedure	Both stages timed accurately, proper agitation, thorough drying	Correct procedure with minor timing deviations	Incorrect timing, inadequate drying, or single-stage wash
Support Removal	Clean removal with flush cutters, minimal surface marks	Supports removed but larger marks remaining	Supports torn off or part damaged during removal
Cure Process	Correct cure time, verified dryness before curing, controlled process	Cure completed but timing or drying not verified	Incorrect cure time, wet part cured, or process errors
Documentation	Complete comparison data for all properties, insightful observations	Most data recorded with reasonable observations	Incomplete data or no meaningful observations

Safety Considerations¶

Nitrile gloves mandatory throughout — uncured resin remains a skin sensitizer until fully post-cured
UV-blocking glasses required during UV curing and whenever the curing station is open
IPA is flammable — keep wash containers away from the UV curing station and any heat source
Compressed air: wear safety glasses, never point at eyes or skin, keep distance from part (15cm)
Post-cured part may be warm (40-60°C) immediately after curing — allow cooling before handling without gloves
Dispose of all contaminated materials per waste protocol (UV-cure paper towels before disposal)

Last Updated: 2026-03-19