Gradient filament — also called rainbow filament — is one of the most exciting materials in 3D printing. With a single spool, you can create beautiful, seamless color transitions that flow naturally from one hue to the next, turning ordinary prints into eye-catching works of art. No multi-extruder system or manual color changes required.
In this guide, we’ll show you exactly how to get the smoothest, most predictable rainbow gradients using SUNLU’s high-quality Rainbow filament series, including PLA Rainbow, Transparent PLA Rainbow, and PLA+ Silk Rainbow.
Understanding Gradient / Rainbow Filament
SUNLU Rainbow filaments are specially designed so the color changes gradually every 8 meters along the filament. As your printer consumes material layer by layer, the model naturally transitions through a full rainbow spectrum — usually from bottom to top — creating a stunning gradient effect without any post-processing.
SUNLU Rainbow Product Line Overview
| Product | Base Material | Surface Finish | Special Characteristics | Color Change Cycle | Best For |
|---|---|---|---|---|---|
| PLA Rainbow | Standard PLA | Matte / classic | Excellent layer bonding, vibrant colors | Every 8 meters | General rainbow prints, toys, decor |
| Transparent PLA Rainbow | Transparent PLA | Clear / glossy | High transparency, good toughness, not easy to break | Every 8 meters | Light-diffusing models, vases, jewelry |
| PLA+ Silk Rainbow | Silk-enhanced PLA | Silky-smooth, shiny | Luxurious silky surface, very vibrant colors | Every 8 meters | Premium decorative items, figurines |
All three variants share these common specs:
- Diameter: 1.75 ± 0.02 mm
- Net weight: 1 kg / spool
- Gross weight: 1.3 kg / spool
- Filament length: ≈ 330 meters (1 kg)
- Bubbles: 100% zero bubbles
- Packaging: Vacuum-sealed with desiccant
Recommended Printing Parameters
Getting perfect color transitions starts with stable, consistent extrusion. Below are the manufacturer-recommended settings for each SUNLU Rainbow variant.
Nozzle Temperature & Print Speed
| Filament Type | Slower Speed (50–100 mm/s) | Higher Speed (100–200 mm/s) |
|---|---|---|
| PLA Rainbow | 200–210 °C | 210–240 °C |
| Transparent PLA Rainbow | 195–205 °C | 205–220 °C |
| PLA+ Silk Rainbow | 205–215 °C | 215–235 °C |
Tip: For the smoothest color transitions, we recommend staying in the lower-to-middle temperature range and printing at 50–100 mm/s when you want more gradual changes. Higher temperatures and faster speeds can slightly accelerate color shifts.
Bed Temperature & Adhesion
- Unheated bed: Apply a thin layer of glue stick
- Heated bed (recommended): 50–60 °C — usually no glue needed
A stable first layer is especially important with rainbow filaments because any adhesion failure will ruin the gradient pattern right from the start.
How to Achieve Perfect, Predictable Color Transitions
1. Match Model Height to Color Cycle
The color changes every ~8 meters of filament. Approximate filament usage per layer depends on your settings:
- Larger models / higher infill / thicker layers → faster color changes
- Smaller models / lower infill / thinner layers → slower, more gradual changes
Quick reference (rough estimates for 0.4 mm nozzle):
- ~0.15–0.20 mm layer height → color change visible roughly every 35–55 layers
- ~0.25–0.30 mm layer height → color change visible roughly every 20–35 layers
2. Control the Speed of Color Change
Want faster rainbow cycling? Print several small models at once, use higher infill (20–30%), or increase the number of perimeters. Want very slow, dreamy gradients? Print tall, thin objects (like vases) with low infill (5–15%) and thin layers (0.12–0.16 mm).
3. Optimize Slicer Settings
- Layer height: 0.12–0.28 mm (thinner = smoother transitions)
- Infill: 10–25% (higher infill = faster color change)
- Wall/perimeter count: 2–4 (more walls = faster color change)
- Flow rate: 98–102% (avoid under-extrusion)
- Cooling: 70–100% after first few layers (especially important for Silk Rainbow)
4. Start at the Right Color
If you want a specific color at the bottom of your print:
- Preview the filament on the spool
- Pull out and load filament until the desired starting color enters the extruder
- Purge until that color starts extruding cleanly
Best Application Scenarios for SUNLU Rainbow Filaments
PLA Rainbow
- Rainbow fidget toys
- Phone stands, cable organizers
- Children’s toys and cartoon figures
- Artistic planters and vases
Transparent PLA Rainbow
- Light-up lampshades and diffusers
- Crystal-style jewelry and ornaments
- Transparent vases and decorative bottles
- LED diffuser covers
PLA+ Silk Rainbow
- High-end figurines and collectibles
- Cosplay accessories
- Luxurious home decorations (candle holders, trays)
- Artistic sculptures and display pieces
Troubleshooting Tips
- Colors change too quickly → Reduce infill, decrease wall count, print taller single object
- Colors change too slowly → Print multiple objects at once, increase infill or walls
- Stringing or oozing → Lower temperature by 5–10 °C, increase retraction distance
- Poor layer adhesion → Slightly increase temperature, make sure bed is perfectly leveled
- First layer issues → Use 50–60 °C bed temperature instead of glue when possible
Conclusion: Start Creating Rainbow Magic Today
With SUNLU’s PLA Rainbow, Transparent PLA Rainbow, and PLA+ Silk Rainbow filaments, you get consistent 8-meter color cycles, zero bubbles, tight diameter tolerance (±0.02 mm), and beautiful gradient results print after print.
Whether you want playful rainbow toys, elegant translucent light effects, or luxurious silky-smooth art pieces — the SUNLU Rainbow series has you covered.
Ready to see the rainbow? Explore the full SUNLU Rainbow collection now and bring vibrant, effortless color transitions to your next 3D printing project!
Happy printing!
