Resin Wash & Cure Time Calculator
Created by: Liam Turner
Last updated:
Calculate optimal IPA wash and UV cure times for resin prints based on resin type, part size, and your curing equipment.
Resin Wash & Cure Time Calculator
3D PrintingCalculate optimal wash and cure times for resin 3D prints based on resin type, part size, and cleaning method.
What is a Resin Wash & Cure Time Calculator?
A resin wash and cure time calculator determines the optimal post-processing schedule for SLA and MSLA 3D printed parts based on the resin formulation, part size, cleaning method, and curing equipment. Proper post-processing is essential for resin prints — uncured or poorly processed parts are sticky, weak, and may off-gas harmful fumes.
Post-processing for resin prints involves three stages: washing to remove uncured liquid resin from the surface, drying to allow the solvent to evaporate, and UV curing to fully crosslink the remaining photopolymer. Each stage has an optimal time window — too short and the part is not properly processed, too long and the part can be damaged.
The wash stage removes uncured resin using IPA (isopropyl alcohol), water (for water-washable resins), or alternative solvents like Mean Green. The curing stage uses 405nm UV light to fully harden the part. Both stages are time-sensitive: under-washing leaves tacky residue, over-washing causes brittleness; under-curing leaves soft spots, over-curing causes yellowing and embrittlement.
This calculator adjusts processing times based on resin chemistry, part size (larger parts have more surface area and internal cavities that trap resin), wash solution effectiveness, and curing equipment power. The result is a customized post-processing timeline that ensures good part quality without the common pitfalls of over-processing.
How the Resin Wash & Cure Time Calculator Works
Wash time starts with a base value per resin type — standard resin needs 3-4 minutes per stage, while tough and engineering resins need 5-7 minutes due to higher viscosity. Part size applies a multiplier: small parts (under 5cm) use 0.7×, medium parts use 1.0×, and large parts use 1.5×.
Temperature affects wash effectiveness — IPA cleans more slowly below 20°C, so a 50% time increase is applied in cold environments. The calculator also recommends the number of wash stages: two stages for IPA and degreaser, one for water-washable resin.
Cure time similarly starts with a resin-specific base value and scales with part size. UV lamp wattage affects the cure speed — a 40W lamp cures roughly twice as fast as a 20W lamp. Sunlight curing uses a 4× multiplier to account for lower and inconsistent UV intensity compared to a dedicated curing station.
Post-Processing Time Formulas
Wash Time = Base × Size Factor × Temperature Factor
Size Factor: Small 0.7, Medium 1.0, Large 1.5
Cold Factor: <20°C adds 50% wash time
Cure Time = Base × Size Factor × (20 / Lamp Wattage)
Sunlight Cure = UV Lamp Time × 4 (approximate)
Total = (Wash × Stages) + Dry Time (5-10 min) + Cure Time
Example Calculations
Small Miniature — Standard Resin, IPA Wash
A small standard resin miniature: wash 2.8 minutes per stage × 2 stages = 5.6 minutes, dry 5 minutes, cure 5.6 minutes with 20W UV lamp. Total post-processing: ~16 minutes. Quick and straightforward for small parts — the entire process fits between removing the part from the printer and starting the next print.
Medium Functional Part — Tough Resin, IPA Wash
A medium tough resin part: wash 7 minutes per stage × 2 stages = 14 minutes, dry 10 minutes, cure 12 minutes with 20W lamp. Total: ~36 minutes. Tough resin needs longer washing due to higher viscosity and longer curing for full mechanical properties.
Large Model — Water-Washable Resin
A large water-washable resin model: wash 6 minutes × 1 stage in water, dry 15 minutes (water takes longer to evaporate than IPA), cure 12 minutes. Total: ~33 minutes. Water-washable resin simplifies cleanup but parts must dry thoroughly before curing to avoid surface hazing.
Common 3D Printing Applications
- Workflow planning — knowing exact post-processing times helps schedule resin printing sessions and plan total project timelines.
- Batch processing — when processing multiple prints, knowing the per-part timing helps batch-optimize wash and cure station usage.
- Quality control — consistent post-processing times ensure uniform part properties across a production run.
- Resin selection — comparing post-processing requirements between standard and water-washable resins helps choose the best option for your workflow.
- Equipment justification — understanding how cure lamp wattage affects processing time helps justify investing in higher-power curing stations.
Tips for Better 3D Printing Results
Let parts dry completely between washing and curing — at least 5-10 minutes for IPA, 15-30 minutes for water. Curing a wet part traps moisture under the cured surface layer, causing hazing, white spots, and reduced mechanical properties.
Rotate parts during UV curing to ensure all surfaces receive even exposure. Shadows from supports or part geometry can leave uncured spots. Most wash-and-cure stations include a rotating turntable for this purpose.
For water-washable resin, do not wash in water for more than 5-7 minutes total. Water-washable resin absorbs water more readily than IPA, and prolonged soaking causes dimensional swelling and weakened parts. Quick, thorough washes produce better results than extended soaking.
Frequently Asked Questions
How long should I wash resin prints in IPA?
Wash standard resin prints for 3-5 minutes per stage in 90-99% IPA, typically using two stages (wash, rinse). Over-washing causes brittleness — never exceed 10 minutes total. Larger parts may need slightly longer due to surface area and trapped resin in cavities. Water-washable resins use the same duration but with water instead of IPA.
Do I need two wash stages?
Two stages produce significantly cleaner results. The first wash removes the bulk of uncured resin, and the second rinse in clean IPA removes residue. Single-stage washing works but leaves a tackier surface. For water-washable resin, a single water rinse is often sufficient because water is cheap and easy to replace.
How long should I cure resin prints under UV?
Standard resin needs 5-10 minutes under a 405nm UV curing station at 20+ watts. Tough and engineering resins may need 10-15 minutes. Flexible resins should not be over-cured as it reduces flexibility. Rotate the part halfway through for even curing. Sunlight works but takes 30-60 minutes and is less consistent.
Can I over-wash or over-cure resin prints?
Yes to both. Over-washing (more than 10 minutes in IPA) causes the part to absorb IPA, leading to brittleness, cracking, and a white or cloudy surface appearance. Over-curing makes parts yellow and brittle, especially clear and flexible resins. Follow recommended times and check the part between stages.
What concentration of IPA should I use?
Use 90% IPA or higher for best results. 99% IPA is ideal — it evaporates quickly and leaves minimal residue. 70% IPA (rubbing alcohol) works in a pinch but contains 30% water that slows evaporation and can leave a hazy surface. Always use fresh IPA — contaminated IPA loses cleaning effectiveness.
How often should I replace the IPA in my wash station?
Replace IPA when it becomes visibly cloudy or yellow, typically after 15-30 prints depending on part size. Contaminated IPA does not clean effectively and deposits partially cured resin back onto parts. You can extend IPA life by straining it through a paint filter and exposing the filtered waste resin to sunlight to cure it for disposal.
Can I cure resin prints in sunlight instead of a UV station?
Yes, sunlight contains 405nm UV light that cures resin. Place parts in direct sunlight for 30-60 minutes, rotating every 15 minutes. Results are less consistent than a UV curing station because sunlight intensity varies with weather, time of day, and season. A $20-40 UV nail lamp works as a budget curing station for small parts.
Sources and References
- Elegoo — "Mercury Plus 2-in-1 Washing and Curing Station Manual" (recommended wash and cure times by resin type).
- Anycubic — "Wash & Cure Machine V3 User Guide" (post-processing best practices and timing guidelines).
- Siraya Tech — "Resin Post-Processing Guide" (detailed wash and cure procedures for standard and engineering resins).
- All3DP — "How to Wash and Cure Resin 3D Prints" (comprehensive post-processing guide with time recommendations).