Vase mode came up briefly in the Christmas tree project post as the technique behind that build’s clean spiral walls, but it deserves the full settings-guide treatment the rest of this “Properly Explained” series gets. It is a genuinely different printing mode from everything else in the slicer, not just a tickbox that makes things print faster, and understanding exactly what it is doing mechanically is what separates a vase that holds water from one that leaks through a hundred microscopic gaps.
What vase mode actually does
Standard printing builds a model from discrete, closed layers — the nozzle completes one full loop, retracts slightly, lifts, and starts the next layer from a defined point. Vase mode — called Spiralize Outer Contour in Cura, Spiral Vase in PrusaSlicer and OrcaSlicer — abandons that structure entirely. The nozzle traces one continuous, unbroken spiral from the base of the model to the top, with the Z-axis rising gradually and constantly rather than stepping up in discrete increments. There is no Z-seam, because there is no layer transition to create one. There are no retractions anywhere in the print, no travel moves between features, and no start/stop artifacts of any kind, because the entire object is one uninterrupted extrusion wound into a tight helix from bottom to top.
The direct consequence of this is the single most important constraint to understand before using vase mode at all: it produces exactly one wall, with zero infill and no top layer whatsoever. There genuinely is no “top” in the conventional sense — the print simply stops rising once it reaches the model’s final height, leaving an open top rather than a closed surface. This is why vase mode is sometimes described as producing hollow objects by definition rather than as an option — a solid or closed-top vase-mode print is not something the technique can produce at all without switching out of vase mode for that specific section.
Why a standard 0.4mm nozzle at default settings produces an eggshell
This is the single most important practical lesson in this whole post, and it is worth stating plainly: printing a vase-mode model at the slicer’s default 0.4mm line width on a 0.4mm nozzle produces a wall as fragile as an eggshell. With no infill and no second wall backing it up, that single 0.4mm-thick wall is the entire structural substance of the object, and a line width matched exactly to the nozzle diameter is the thinnest, weakest version of that wall possible.
The fix is to deliberately widen the line width well beyond the nozzle’s own diameter — a 0.4mm nozzle can reliably extrude lines up to roughly 0.8mm wide, 200% of its own diameter, without losing layer adhesion between the spiral windings. This produces a wall twice as thick and significantly stronger than the default, and it is genuinely the single highest-leverage setting in the entire vase mode workflow. Line width, not layer height and not wall count, since there is only ever one wall, is what actually determines whether a vase-mode print is structurally sound or paper-thin.
The settings, properly explained
| Setting | Recommended value (0.4mm nozzle) | Why |
|---|---|---|
| Line width | 0.6-0.8mm | The genuine strength lever — a wider single wall is dramatically more durable than a default-width one, at the cost of slightly less fine surface detail |
| Layer height | 0.2mm for detail; 0.28-0.3mm for speed | Finer layer heights resolve surface texture and gradient colour transitions, exactly as used in the Christmas tree vase mode post, more cleanly; coarser heights print faster with more visible layer lines |
| Print speed | 40-50mm/s on the outer wall | Printing too fast introduces ringing even in a continuous spiral, since the toolhead’s own momentum and vibration do not disappear just because retraction has been eliminated — see the ghosting and ringing post |
| Infill | 0% (enforced automatically by vase mode) | Not user-adjustable once vase mode is enabled — the whole technique depends on there being no infill at all |
| Wall loops | 1 (enforced automatically) | Vase mode only functions with a single wall; most slicers will not expose the spiralize checkbox at all until wall count is set to 1 |
| Top shell layers | 0 (enforced automatically) | There is no top surface to generate in vase mode |
| Flow rate | 105-110% | A small, deliberate flow boost helps close the tiny gaps between spiral windings and improves layer-to-layer bonding within the continuous wall |
| First layer height | Slightly taller than normal — around 120% of nozzle diameter | A thicker first layer gives the spiral a solid, well-adhered foundation to build from before the wall thins out for the rest of the print |
Where to find it
Bambu Studio and OrcaSlicer: Process → Others → Spiral Vase (sometimes labelled Spiralize or Special Mode depending on version), with a toggle that becomes available once wall loops is set to 1. Enabling it automatically forces infill to 0% and top shell layers to 0, since both would be structurally meaningless in a single continuous wall. The slicer will typically prompt if other enabled settings conflict with vase mode — worth reading that prompt rather than dismissing it, since it usually flags something genuinely incompatible rather than a false alarm.
Why a larger nozzle is sometimes the better answer than line width alone
This connects directly to the nozzle size guide‘s broader argument about matching nozzle diameter to the job rather than defaulting to 0.4mm for everything. Pushing a 0.4mm nozzle to 0.8mm line width is already stretching that nozzle toward the upper edge of what it can reliably extrude. Switching to a genuine 0.6mm nozzle and running a 1.0mm line width at 0.2mm layer height achieves a reliably watertight result more comfortably than forcing a 0.4mm nozzle to its limit — worth considering specifically for anything intended to actually hold water or liquid rather than just stand decoratively on a shelf.
Making it genuinely watertight
A vase-mode print that will actually hold water needs more than just a wide line width. PETG is the better material choice here over PLA specifically because of its superior layer adhesion, covered in the PETG materials post — a single continuous wall with imperfect bonding between spiral windings is exactly the scenario where PETG’s toughness advantage over PLA matters most. For genuine water-tightness, the combination that comes up consistently is 0.8mm line width on a 0.4mm nozzle printed in PETG, or 1.0mm line width on a 0.6mm nozzle — and coating the interior afterward with epoxy or a clear spray sealant as a belt-and-braces finish, since even a well-printed single wall can have microscopic pinholes that only reveal themselves once water is actually standing against them for a while.
Designing or choosing a model that actually works in vase mode
Not every model that looks simple is actually suited to vase mode, and this catches people out regularly. The outer wall must be a single continuous profile from bottom to top with no overhangs that would require support — vase mode cannot be printed with supports at all, since a support structure would need its own separate wall loops and infill logic that the technique simply does not have room for. Models designed specifically for vase mode typically flare slightly outward at the base for print stability, favour gentle curves over sharp angles, and either taper gradually or remain vertical throughout rather than including a genuine undercut anywhere in the profile — exactly the geometry the Christmas tree in the earlier project post relied on, tapering steadily from a wide base to a narrow tip with no undercut at any point along that taper.
Before committing a model to a full vase-mode print, switch to the slicer’s layer preview and confirm the toolpath genuinely shows one continuous, unbroken spiral rather than multiple separate loops. A model with an unintentional thickness variance — common in files exported from Tinkercad or produced through a boolean operation in other CAD software — can silently force the slicer back into multiple walls or introduce a break in the spiral that defeats the whole point of the technique, and this is something worth catching in the preview rather than discovering on the finished print.
When vase mode genuinely wins, and when it does not
Vase mode is the right choice for decorative vases, lampshades, and thin-walled ornamental pieces — exactly the Christmas tree project category — where the complete absence of a visible seam, combined with genuinely fast print times and low material use, matters more than raw structural strength. It is also the ideal delivery mechanism for a height-dependent colour gradient, since the whole print is one continuous vertical run with no seam or wall-junction interruption to break the colour transition up, exactly as covered in the earlier project post’s discussion of rainbow gradient PLA.
It is the wrong choice for anything that needs genuine structural strength, anything with overhangs that cannot be designed around, and anything requiring batch printing of multiple different models on one plate — vase mode’s continuous single-spiral nature means a plate is typically dedicated to one model at a time rather than the kind of multi-item plate layout covered in the print queue post. For a functional container, a load-bearing part, or anything that needs to survive being knocked or dropped, standard multi-wall printing with proper infill remains the correct choice regardless of how appealing the seamless vase-mode finish looks.
