The first layer of a 3D print is the most important—if it fails, the entire print likely will too. Along with bed temperature, leveling, and surface prep, one of the most overlooked yet powerful tools to ensure a solid first layer is build plate adhesion settings in your slicer software.
Modern slicers such as Cura, PrusaSlicer, Bambu Studio, and SuperSlicer offer built-in options like skirts, brims, and rafts. These settings influence how your print adheres to the build plate during the early layers and can make a significant difference, especially with challenging filaments or large models.
This guide breaks down how each setting works, when to use them, and how to configure them effectively—ensuring greater print reliability and fewer failures.
What Are Build Plate Adhesion Settings?
Build plate adhesion settings control how the first few layers of a print interact with the build surface. Rather than altering the model itself, these features add auxiliary structures around or beneath the model to improve contact, balance, and grip.
Slicer software generally provides three main options:
- Skirt – Outline around the model
- Brim – Flat extension around the model’s base
- Raft – A separate printed base under the model
Each has distinct use cases depending on the model shape, filament behavior, and bed condition.
1. Skirt: Priming the Nozzle Without Touching the Print
What It Does:
A skirt prints one or more perimeter lines around the model without touching it. It serves as a nozzle primer rather than an adhesion aid.
Key Benefits:
- Primes the nozzle and clears partial clogs or oozing.
- Allows the user to observe the first layer before actual printing.
- Verifies bed leveling and extrusion consistency.
Ideal Use Cases:
- Small models with reliable adhesion.
- Every print, as a diagnostic check.
- Multicolor or multi-material prints to stabilize transitions.
Settings to Configure:
- Skirt Line Count: 2–3 is typical.
- Skirt Distance: 3–5 mm from the model is common.
- Minimum Length: Forces the printer to lay a longer line for nozzle priming.
Best Practices:
- Always enable for daily printing, even if not using brims or rafts.
- Helps confirm filament flow before wasting material.
2. Brim: Adding Grip Around the Base of the Model
What It Does:
A brim prints additional lines attached to the model’s first layer, radiating outward from its base. Unlike a skirt, it is physically connected to the print.
Key Benefits:
- Increases surface area for the first layer.
- Strongly improves adhesion for small bases or tall models.
- Helps anchor corners to reduce warping.
- Easy to remove post-print.
Ideal Use Cases:
- Narrow, tall prints that risk tipping or detaching.
- Warping-prone materials like ABS or PETG.
- First prints on a new or untested build surface.
Settings to Configure:
- Brim Width: Typically 5–10 mm.
- Brim Line Count: Determines how many lines expand from the model’s base.
- Brim Only on Outside (if available): Keeps the brim from entering holes or inner geometry.
Best Practices:
- Combine with a well-leveled bed and proper Z-offset.
- Remove brims using tweezers or a deburring tool for clean edges.
- Adjust slicer profiles per material (e.g., more brim lines for PETG than for PLA).
3. Raft: A Full Support Base Beneath the Print
What It Does:
A raft is a multi-layer platform printed underneath the model. The actual part begins a few layers above this raft, which acts as a sacrificial foundation.
Key Benefits:
- Compensates for uneven or damaged build plates.
- Greatly improves first-layer adhesion and print leveling.
- Prevents warping on large or high-temp prints.
- Ensures even print bases regardless of bed surface condition.
Ideal Use Cases:
- Unreliable or damaged build surfaces.
- Very large prints with wide cross-sections.
- Materials with extreme warping (ABS, Nylon, PC).
- Models with very small contact points.
Settings to Configure:
- Raft Layers: The number of interface and base layers.
- Separation Distance: Space between raft and model (affects removal ease).
- Extra Margin: Space the raft extends beyond the model’s base.
- Raft Top Layers: Smooths the surface the model begins printing on.
Best Practices:
- Ensure good first-layer height for the raft itself.
- Increase raft air gap for easier separation but lower it for better quality.
- Be prepared to spend more filament and time—rafts use significantly more resources.
Advanced Adhesion Settings and Features
In addition to the three main types, many slicers include other options to refine adhesion:
A. Z Offset Adjustments (Initial Layer Height)
Your slicer allows you to set a specific height for the first layer, often slightly thicker than the rest to promote better contact.
- Initial Layer Height: Typically 0.2 mm or more for better adhesion.
- Initial Layer Line Width: 110%–120% is common to ensure a solid base.
These settings improve adhesion even without skirts, brims, or rafts.
B. Flow Rate for First Layer
Increasing the flow rate for the initial layer enhances bed bonding:
- Use 105%–110% flow on the first layer.
- Combine with slightly lower speed for best results.
C. Initial Layer Speed
Slower speed during the first layer gives the filament time to melt and grip:
- Recommended: 15–30 mm/s depending on the material and printer.
This is often one of the most overlooked factors affecting adhesion success.
Choosing the Right Adhesion Setting by Situation
Here’s a quick reference chart to help you decide:
| Scenario | Best Adhesion Method |
|---|---|
| Small part with narrow base | Brim |
| Large flat model using ABS | Raft |
| PETG on smooth PEI (to prevent damage) | Glue + Brim |
| Model on dirty or uneven bed | Raft |
| Routine PLA print with no issues | Skirt |
| Delicate model with small supports | Brim |
Use these settings strategically, not by default. Adding unnecessary brims or rafts slows down prints and increases post-processing work.
Common Misconceptions About Adhesion Settings
“A raft guarantees a perfect first layer.”
Not always. Rafts hide bed imperfections but don’t solve poor leveling or incorrect Z-offset. They consume more filament and time, and are hard to remove cleanly if misconfigured.
“A skirt improves adhesion.”
False. A skirt only helps prime the nozzle—it does not affect bed grip. It’s still valuable for catching issues early but should not be relied on for adhesion help.
“Brims always work for every material.”
Incorrect. While brims help with warping, some filaments like PETG may bond too aggressively to textured PEI, damaging the surface even with brims. In such cases, use a glue stick as a barrier.
“All slicers handle brims and rafts the same way.”
Not true. Cura, PrusaSlicer, and Bambu Studio handle brim expansion, interface layers, and removal differently. Always test your slicer’s behavior before assuming universal results.
Maintenance Tips After Using Adhesion Helpers
- Clean the bed surface after every print, especially after rafts or glue.
- Inspect nozzles for filament residue caused by overly squished first layers.
- Check calibration if rafts and brims are becoming necessary for previously successful prints—something else may be off (e.g., leveling or wear).
FAQs
Do I need adhesion settings for every print?
No. For well-calibrated printers using materials like PLA or PETG on clean PEI, a skirt may be all you need. Reserve brims and rafts for problem prints or tricky geometries.
How do I remove a brim or raft cleanly?
Use flush cutters or a deburring tool. In slicers like PrusaSlicer, enable settings to reduce contact between the brim and model for easier separation.
Is a raft always better for large prints?
Rafts offer maximum adhesion, but they also increase time and filament use. A well-leveled bed with a brim and correct temperature is often sufficient for large prints.
Can I combine adhesion types?
Yes. A skirt and brim combo is common. Most slicers won’t let you use all three (skirt, brim, raft) at once, but layering brim + glue or brim + slow speed works well.
Why are my brim lines detaching mid-print?
Check for:
- Dirty build surface
- Incorrect first-layer height
- Nozzle too high
- Uneven bed
Brims must be squished enough to hold tight. Recalibration often solves this.
Conclusion
Build plate adhesion settings are an essential tool in any slicer’s toolbox. Knowing when and how to use skirts, brims, and rafts can drastically improve first-layer success, reduce failed prints, and improve overall print quality.
Use skirts for monitoring, brims for grip, and rafts as a last resort when the bed or material demands it. Combine these settings with proper calibration, clean surfaces, and thoughtful material handling—and you’ll eliminate adhesion problems before they even begin.