With the rapid rise of resin-based 3D printing, choosing the right UV light wavelength—typically 385nm or 405nm—has become a crucial decision that directly affects print quality, resin compatibility, and production efficiency. While both are common in SLA, DLP, and LCD systems, they serve different needs depending on your application.
This guide offers a comprehensive breakdown of 385nm vs 405nm, including the science, differences in practice, and tips for choosing the right wavelength for your use case.
🔬 Wavelength Basics: 385nm vs 405nm
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385nm (UV-A): Shorter wavelength, higher energy. Usually sourced from UV LEDs or lasers. Offers faster curing and better resolution.
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405nm (Near-UV/Violet): Slightly longer wavelength, lower energy. More commonly used in consumer printers due to affordability and LCD screen compatibility.
💡 In general, shorter wavelengths penetrate less deeply but cure more precisely, while longer wavelengths cure more gradually and uniformly.
⚙️ Key Technical Differences
| Attribute | 385nm | 405nm |
| Energy Output | Higher; fast surface curing | Lower; cures more gradually |
| Cure Speed | Rapid, 2–3s in advanced systems | Moderate, requires longer exposure |
| Cure Depth | Shallow; high precision | Deeper penetration; good interlayer adhesion |
| Printing Accuracy | Ideal for fine features and micro details | Lower precision; better for thick layers |
| Transparency | Superior; less light scattering | More prone to edge blur and yellowing |
| Hardware Cost | Higher; used in professional DLP systems | Lower; supports affordable LCD printers |
| Safety | Requires better shielding (stronger UV) | Safer; lower protection threshold |
| Printer Type | Common in DLP and high-end SLA | Common in LCD printers |
🧪 Application-Based Recommendations
✅ Use 385nm if you need:
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High-resolution prototypes (e.g. microfluidics, MEMS, or dental models)
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Transparent or optically critical parts (e.g. lenses, jewelry masters)
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Fast curing at lower heat (e.g. silver nanowire conductive inks)
Example: In the dental industry, 385nm DLP printers enable the fabrication of crowns, bridges, and surgical guides with exceptional dimensional accuracy and smooth surface finish. Thanks to the shorter wavelength and higher energy output, the light penetrates less deeply, minimizing overcuring and preserving fine details—critical for components that must fit precisely within the human mouth.
✅ Use 405nm if you want:
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Affordable general-purpose printing (e.g. prototypes, figurines)
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Flexible or thick-layer parts (e.g. TPU-like materials)
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Entry-level or educational applications where budget matters
Example: For small studios and DIY users printing cosplay parts or batch models, 405nm printers offer cost efficiency, broader resin availability, and less need for high-precision tuning.
❓ Common Industry Questions
Q1: What happens if I use the wrong wavelength?
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No curing: A 385nm-only resin won’t cure under 405nm light.
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Print failures: Mismatch leads to incomplete cross-linking, weak layers, or tacky surfaces.
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Blurry details: 405nm can cause unwanted scattering in transparent prints.
Q2: Why do some resins only work with 385nm or 405nm light?
Different resins use photoinitiators that are sensitive to specific wavelengths. If the printer's light source doesn't match the resin's absorption peak, curing will be incomplete or fail entirely. Always check the resin’s datasheet for compatible wavelengths before printing.
Q3: Does wavelength affect the surface quality of the print?
Yes. Shorter wavelengths like 385nm reduce light bleed and cure more precisely, resulting in sharper details and smoother surfaces—especially noticeable in small features or transparent parts. 405nm tends to have slightly more diffusion, which may blur fine edges in high-resolution prints.
Q4: How to improve success with thick prints?
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Extend exposure time under 405nm to boost penetration.
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Use layered curing strategy: cure outlines first, then infill, to reduce internal stress.
🧾 Conclusion: Choose Based on Use Case, Not Just Specs
| Need | Best Choice |
| High-precision & transparency | 385nm |
| General use & affordability | 405nm |
| Thick layers & bonding | 405nm |
| Short cure time & conductivity | 385nm |
Final Tip: Don’t just look at the printer specs—understand your resin’s absorption curve, part geometry, and desired finish quality. For high-performance industrial applications, 385nm is often the smarter long-term investment. For quick prototyping or hobbyist use, 405nm continues to offer unbeatable value.
