Print Quality
Z-Seam & Scarf Seam Guide
Use scarf seams on smooth curves; use aligned or corner placement on edged parts. Here are the current controls and a safe tuning order.
TL;DR
- Smooth curved wall: start with a contour scarf seam and the slicer's defaults.
- Edged part: use aligned, back or corner placement, or paint the seam onto a hidden face.
- Calibrate pressure advance and retraction before changing scarf length, speed or flow.
- Change one control at a time on a small test cylinder; there is no universal material recipe.
Scarf seam settings: start here
These are current OrcaSlicer defaults or official recommendations, not universal best settings. Bambu Studio and PrusaSlicer use related controls, but names and defaults must be checked in each slicer.
| Control | Safe starting point | Evidence status |
|---|---|---|
| Scarf type | Contour; use conditional application on smooth curved walls | Official Orca/Prusa behavior[1][2] |
| Scarf length | Leave the profile default first; Orca documents 20 mm as its example default | Official Orca default[2] |
| Scarf steps | Leave at 10 until a test print shows a stepped transition | Official Orca default[2] |
| Scarf speed | Do not exceed the relevant wall speed; Orca recommends less than 100 mm/s | Official Orca recommendation[2] |
| Scarf flow ratio | Start at 100%; reduce only to diagnose measured over-extrusion | Official Orca recommendation[2] |
| Entire wall / inner walls | Leave off unless the model or an inner-hole seam gives you a reason to test it | Official Orca guidance[2] |
Tune in this order: pressure advance and retraction, seam placement, scarf speed, scarf length, then flow ratio. Save the original profile and compare one change at a time.
A scarf seam (also called a scarf joint seam) ramps extrusion through an overlap at the start and end of a perimeter. It can reduce the visible Z-seam on smooth surfaces, but the result depends on geometry, extrusion calibration and the slicer's implementation.[1][2]
What Is a Z-Seam?
Every perimeter loop on every layer has to start somewhere and end somewhere. Where those two points meet is the seam.
When your printer finishes one perimeter and moves to the next layer, the nozzle has to stop extruding, retract, travel up, and start extruding again. That stop-start transition leaves a small bump, zit, or line on the surface of the print. On parts with flat faces or sharp corners, you can often hide this transition in geometry. On cylinders and organic curved shapes, there is nowhere to hide it — and it shows.
The Z-seam gets its name because the nozzle moves in the Z direction (up) between layers. Every FDM print has one, and on most prints it is the single most visible surface imperfection. Glossy and silk filaments make it worse because they reflect light off the bump. Transparent filaments are even more unforgiving — you can see the internal overlap through the wall.
Your slicer controls where the seam lands and, in more recent slicers, how the extrusion starts and stops at the seam point. Understanding the options is the first step to dealing with it.
Seam Types Compared
Every slicer offers multiple seam placement strategies. Each has tradeoffs — there is no single best option for all parts.
Aligned
All seams stacked on a single vertical line. Predictable and easy to sand or post-process. Creates one visible line on the surface — very obvious on cylinders but easy to orient toward the back of a part. Best when you can control part orientation on the build plate.
Random
Seam position randomized every layer. Eliminates the single vertical line but scatters small zits across the entire surface. Generally the worst option for surface quality. Each random point is a tiny blob that catches light differently. Avoid unless you are sanding the entire part anyway.
Sharpest Corner
Slicer tucks the seam into the sharpest available corner on each layer. Hides the seam in geometry where it is least visible. Best automatic option for parts with corners and edges. Struggles on cylinders and organic shapes that have no sharp corners to hide in.
Nearest
Minimizes nozzle travel by placing the seam at the closest point. Slightly faster print times but unpredictable placement with poor cosmetic results. Rarely a good choice for visible parts. Useful for internal structures or functional prints where speed matters more than appearance.
Scarf Joint
Instead of a blunt start and stop, the slicer gradually ramps extrusion through a tapered overlap. This can reduce the seam bump on suitable geometry. It still needs a calibrated extrusion profile and a test print.
Default recommendation
Use sharpest corner as your everyday default. Switch to scarf joint for cosmetic prints with curved surfaces. Use aligned when you plan to sand or hide the seam against a wall.
Scarf Seams Explained
A scarf joint changes the start and end of a perimeter to reduce visible seam defects. Here is how the documented implementations work.
A traditional seam works like this: the nozzle starts extruding at full width, prints the entire perimeter, then stops extruding and retracts. Where the start meets the end, you get a double-thickness overlap — a visible bump. No amount of retraction tuning fully eliminates it because the fundamental problem is geometric: two blunt ends overlapping.
A scarf joint seam takes a different approach. Instead of an abrupt start and stop, the slicer ramps extrusion through an overlap. The goal is a smoother transition with a less visible bulge or gap; actual results depend on the profile, printer and geometry.[1][2]
The name comes from woodworking. A scarf joint connects two boards by cutting matching angled faces, so they overlap into a flush joint instead of butting end-to-end. The same principle applies here — a gradual taper instead of an abrupt transition.
Current slicer support
Reviewed September 2026: OrcaSlicer and PrusaSlicer both document scarf controls in their current official guides.[1][2] Bambu Lab also provides an official Bambu Studio settings walkthrough.[3] Treat each as a separate interface: similar labels do not establish parity in defaults or behavior.
This guide does not claim current Cura support because no stable official Cura scarf-seam documentation was available for this review. Use your installed slicer's own documentation and release notes rather than an old compatibility claim.
How the Flow Ramp Works
Start of Perimeter
The slicer ramps the scarf transition across its configured length. Leave the current profile default first, then change it only after a controlled test shows a specific defect.[2]
End of Perimeter
Extrusion width ramps down from full to near zero over the same distance. The taper zone at the end overlaps the taper zone at the start. Combined, they equal one normal extrusion width.
Why It Works
Traditional seams fail because full width + full width = double width at the overlap. Scarf seams succeed because half width + half width = normal width. The transition is smooth enough that the surface looks continuous.
Slicer Settings
Setting names from official documentation, reviewed September 2026. Defaults and available controls vary by slicer and profile.
| Slicer | Setting Name | Location | Key Options |
|---|---|---|---|
| OrcaSlicer | Scarf joint seam | Quality → Seam | Type, conditional application, speed, height, entire wall, length, steps, flow ratio and inner walls.[2] |
| Bambu Studio | Scarf joint seam | Quality → Seam | Use the controls shown in Bambu Lab's current walkthrough; do not copy Orca values blindly.[3] |
| PrusaSlicer | Scarf joint placement | Print Settings → Seam | Placement, smooth-perimeter behavior, start height, entire perimeter, length, segment length and inner perimeters.[1] |
OrcaSlicer scarf speed
OrcaSlicer recommends less than 100 mm/s and will cap scarf speed at the relevant wall speed if that is lower. This is Orca guidance, not a universal Bambu Studio or PrusaSlicer default.[2]
Inner walls
OrcaSlicer documents inner-wall scarf as usually unnecessary for appearance. Leave it off initially; test it only when an inner-hole seam is part of the visible problem.[2]
Other slicers
Do not transfer names or numbers from this table to another slicer. Check the installed version's official documentation first; unsupported capability claims age quickly.
When to Use Scarf Seams
Scarf seams help most on materials and geometries where seams are most visible. Not every print needs them.
Biggest Benefit
Silk & Glossy PLA
Glossy surfaces reflect light directly off the seam bump, making it the most obvious imperfection on the part. Scarf seams make the biggest visible difference here. Silk PLA is also where brand quality varies most, so it pays to compare the cheapest PLA filament prices across stores. See all material types →
PETG
PETG is prone to blobbing and stringing at seam points due to its higher melt viscosity. The gradual flow ramp of scarf seams avoids the pressure spike that causes PETG seam blobs. Still deciding between the two materials? See PLA vs PETG.
Transparent Filament
Translucent and clear filaments show internal overlap through the wall. A scarf seam's flush overlap is far less visible than the double-wall bump of a traditional seam.
Cylinders & Organic Shapes
No corners to hide the seam in. On a smooth cylinder, every seam type except scarf leaves a visible mark. This is where scarf seams earn their keep.
Moderate Benefit
Standard PLA
Seams are visible but less glaring than on glossy variants. Scarf helps, especially on curved surfaces, but the improvement is less dramatic.
ABS / ASA
These materials handle retractions reasonably well, and their matte finish helps hide seams naturally. Scarf still improves curved parts but the baseline is already decent.
Least Benefit
Matte PLA / Textured Filaments
Matte surfaces scatter light and naturally hide seam bumps. Wood-fill, carbon fiber fill, and other textured filaments do the same. Scarf still works but the visual improvement is marginal.
Skip For These
Vase / spiral mode: There is no layer seam in spiral mode — scarf does not apply. Very small perimeters: If the perimeter is shorter than the taper distance, the ramp cannot develop properly and may cause artifacts instead of fixing them.
Scarf Seam Gotchas
Scarf seams work well when the conditions are right. Here is what can go wrong and how to avoid it.
Short perimeters cause artifacts
Pressure advance must be calibrated first
Scarf seams rely on your extruder responding predictably to flow changes. If pressure advance (Klipper) or linear advance (Marlin) is uncalibrated, the actual flow will lag behind what the slicer expects, and the taper will not be smooth. Calibrate pressure advance before enabling scarf →
Taper zone landing on sharp corners
If the scarf taper happens to overlap a sharp corner, the reduced extrusion width at that corner can cause a visible gap or under-extrusion. Use the seam position setting (e.g., aligned to a flat area) to steer the taper zone away from corners.
High print speeds reduce precision
If a scarf transition is inconsistent, test a lower scarf speed after pressure advance and retraction are calibrated. In OrcaSlicer, stay below the relevant wall speed and its documented recommendation of 100 mm/s.[2]
Not retroactive
Changing the seam setting in your slicer does not fix already-sliced G-code. You need to reslice the model and send the new file to your printer. Sounds obvious, but it catches people who change settings mid-queue.
Bowden extruders are harder to tune
A long filament path can change pressure response, but that does not prescribe one length or speed. Calibrate the filament profile, print the same test geometry, and adjust only the control tied to the observed defect.
Seam Optimization Tips
These apply to all seam types, not just scarf. Get these right first — they make every seam strategy work better.
Calibrate pressure advance / linear advance first
This is the single most impactful tuning step for seam quality. Pressure advance compensates for the delay between extruder motor commands and actual filament flow. Without it calibrated, every seam type will blob at the start and gap at the end. Speed & pressure advance guide →
Use slicer-specific seam controls
Seam gap, wiping and coasting are not interchangeable across slicers. Use the installed version's terminology and defaults, then tune against one repeated test print.
Align the seam to the back of the part
If you are using aligned seam positioning, rotate the model on the build plate so the seam line faces a wall, the back of a display piece, or any surface that will not be seen. This costs nothing and hides the seam for free.
Use sharpest corner as your default
For everyday prints with mixed geometry, sharpest corner gives the best automatic results without any manual positioning. Switch to scarf for cosmetic curved parts, aligned for parts you plan to sand.
Clean your nozzle tip
Residual filament on the nozzle tip gets dragged to the seam start point, adding extra material to an already-sensitive area. A quick wipe with a brass brush before starting a cosmetic print makes a noticeable difference.
Tune retraction before blaming the seam type
Under-retraction causes oozing at the seam. Over-retraction causes gaps. If every seam type looks bad, the problem is likely retraction distance or speed, not the seam positioning itself. Troubleshooting guide →
Reduce outer wall speed for cosmetic parts
If scarf seams remain inconsistent after calibration, reduce scarf or outer-wall speed in one controlled step and compare the same geometry. Preserve the original profile so the result is reversible.
Tune Scarf Seams by Symptom
Material, moisture, temperature and extrusion hardware interact. Diagnose the visible defect instead of applying an unsupported material recipe.
| What you see | Check first | Next controlled test | Evidence status |
|---|---|---|---|
| Bulge at the seam | Pressure advance, flow and seam gap | After calibration, test a lower scarf speed or a small seam-gap change | Orca troubleshooting sequence[2] |
| Notch or under-extrusion | Pressure advance, retraction and flow ratio | Return flow ratio to 100%, then test one length or speed change | Orca default/recommendation[2] |
| Artifact on a corner | Placement and conditional scarf | Keep scarf on smooth contours; place a conventional seam on the corner | Official Orca/Prusa behavior[1][2] |
| Inconsistent result by filament | Moisture, temperature, flow and retraction | Dry and recalibrate that filament before changing scarf controls | SpoolHound diagnostic starting point, not a slicer default |
| No meaningful improvement | Whether geometry already hides the seam | Compare scarf off/on; keep the simpler setting if the result is equivalent | Project-specific visual test |
The repeatable test: print a small cylinder in your actual filament with scarf off, then on, from otherwise identical profiles. If scarf does not improve the result, return to the original profile and calibrate extrusion before adding more variables.
Appearance is project-specific. Gloss, pigment, layer height and lighting change how visible a seam looks. Treat material advice as a reason to test, not a guaranteed ranking.
Printer Compatibility
Scarf is generated by the slicer, while the printer and filament profile determine how closely the extrusion follows that toolpath.
Bambu printers with Bambu Studio
Use the controls and locations shown in Bambu Lab's current walkthrough.[3] Keep the selected printer and filament profile intact for the first test; do not import Orca defaults as though they were identical.
OrcaSlicer-supported printers
Use the printer's correct machine profile, then start with Orca's documented scarf defaults and limits.[2] Printer support does not prove that one setting works across models.
Prusa printers with PrusaSlicer
Use PrusaSlicer's documented scarf placement and smooth-perimeter controls with the matching printer profile.[1] Do not infer a version floor or copy Orca-only controls without an official release source.
Long-path and Bowden extrusion systems
The filament path can alter pressure response. Calibrate the material profile and compare identical test parts before deciding whether length or speed needs adjustment; there is no supported universal 15 mm / 50% recipe.
Voron / custom Klipper builds
Calibrate pressure advance per filament, then use scarf controls that the selected slicer version actually documents. Save a separate test profile rather than overwriting a known-good production profile.
Creality K1 / K1 Max / K2 Plus (direct drive, Klipper)
If using OrcaSlicer, verify the exact printer profile and firmware workflow before testing scarf. This guide makes no claim about current Creality Print feature parity.
Ender 3 / CR-10 series (Bowden, Marlin)
Confirm firmware and slicer compatibility first. If pressure advance or linear advance is unavailable, use seam placement and a calibrated retraction profile rather than assuming hardware changes are required.
Elegoo Centauri Carbon / Anycubic Kobra (direct drive)
Do not infer scarf support from a slicer's ancestry. Verify the installed vendor slicer's documentation, or use a supported OrcaSlicer profile and its documented controls.
Bowden owners
Start with calibration and a controlled comparison. Hardware upgrades are outside this settings guide and should not be prescribed without a measured extrusion problem.
Frequently Asked Questions
How do I get rid of the Z seam completely?
You cannot fully eliminate the start and end point on a normal closed FDM perimeter. You can reduce its visibility with a scarf transition, place it on a hidden edge or corner, use seam painting, or post-process the surface. Spiral vase mode removes the layer-to-layer start/stop seam, but it is limited to compatible continuous single-wall geometry.
What is a Z seam in 3D printing?
The Z seam is the faint vertical line on a print's outer wall where each layer's perimeter starts and ends. Because slicers usually stack these start points on top of each other, the individual layer blobs line up into a visible seam running up the Z axis. It is a geometry artifact, not a defect in your filament or printer. The full explanation covers why it forms and the settings that control where it lands.
What does seam gap distance do in PrusaSlicer?
Seam gap stops extrusion slightly before the perimeter loop closes, leaving a tiny unfilled gap that the nozzle's residual pressure fills as it passes. It exists to prevent the bulging blob you get when a loop's end overlaps its start. The value is a percentage of nozzle diameter: raise it if your seams bulge outward, lower it if you see a visible notch or gap at the seam line. Tune it after pressure advance, not before, because pressure advance fixes most of what seam gap papers over.
What are the best scarf seam settings?
For a smooth curved wall, start with contour scarf and the correct printer and filament profile. In OrcaSlicer, leave the documented defaults of 20 mm length, 10 steps and 100 percent flow initially; keep scarf speed no faster than the relevant wall and below 100 mm/s. Leave entire-wall and inner-wall scarf off unless the geometry gives you a reason to test them. These are Orca settings reviewed in September 2026, not universal values for Bambu Studio or PrusaSlicer.
What is a scarf seam in 3D printing?
A scarf seam, or scarf joint seam, ramps extrusion through an overlap at the start and end of a perimeter. Its purpose is to reduce the visible bulge or gap caused by an abrupt seam. It can improve a suitable curved surface, but it does not guarantee an invisible seam; calibration, geometry and slicer behavior still matter.
Which slicers support scarf seams?
As reviewed in September 2026, OrcaSlicer and PrusaSlicer document scarf seam controls in their official guides, and Bambu Lab publishes a Bambu Studio scarf-settings walkthrough. Names, locations and defaults differ, so check the installed slicer's current documentation. This guide does not make a current Cura support claim without a stable official source.
Does scarf seam work with all filament materials?
Scarf seams work with most materials but benefit some more than others. Silk and glossy PLA, PETG, and transparent filaments see the biggest improvement because seams are most visible on shiny and clear surfaces. Matte PLA, wood-fill, and carbon fiber filaments already hide seams through surface texture, so the visual improvement is smaller. Very fast-oozing materials may not respond well to the gradual flow ramp.
Should I use scarf seam for every print?
Not necessarily. Scarf seams are best for cosmetic parts, especially curved or cylindrical shapes where traditional seams create a visible line. For functional parts, parts with sharp corners that naturally hide seams, or very small perimeters where the taper cannot develop properly, sharpest corner positioning is often a better default. Use scarf when appearance matters; use sharpest corner for everything else.
Can I combine scarf seam with aligned seam positioning?
Scarf treatment and seam placement are separate controls in documented slicers, but the available combinations and labels differ by product. In OrcaSlicer, choose a placement strategy and scarf behavior within the Seam controls. In PrusaSlicer, follow its scarf placement and smooth-perimeter options. Preview the sliced toolpath rather than assuming cross-slicer parity.
Do scarf seams affect print strength?
Do not assume a strength improvement. OrcaSlicer describes a possible slight benefit at the seam, but that is not a printed-part strength guarantee. For a structural part, test the actual geometry and orientation under its expected load; wall design, layer adhesion and process consistency remain separate variables.
Matte PLA hides residual seam artifacts better than silk or glossy finishes. Compare matte PLA from 30+ brands.
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- Prusa Knowledge Base, "Seam position." Official PrusaSlicer seam and scarf controls. Reviewed September 2026.
- OrcaSlicer official GitHub Wiki, "Quality settings: seam." Official OrcaSlicer seam settings. Defaults, recommendations and troubleshooting; reviewed September 2026.
- Bambu Lab Support, "Bambu Studio Scarf Seam Explained: Settings Walkthrough." Official Bambu Lab video walkthrough. Published May 2026; reviewed September 2026.
- Ellis' Print Tuning Guide, pressure advance calibration and seam tuning. ellis3dp.com/Print-Tuning-Guide. Independent tuning reference.