If you've ever looked at a finished print and thought the top surface looks rough and lined compared to the sides — ironing fixes that. It's a post-processing pass the slicer adds after the final top layer, and when it's set up correctly, it turns a textured surface into something that looks almost injection-moulded.
It's one of those features that sounds fiddly but takes about two minutes to set up, and the results speak for themselves.
Ironing is an extra pass the printhead makes over the top surface after it finishes the final layer. The nozzle moves slowly back and forth across the surface, either extruding a very small amount of filament or nothing at all, remelting and smoothing the top layer as it goes.
The effect: instead of parallel ridged lines from the last top layer, you get a flat, smooth, slightly glossy surface.
Ironing works best on:
It's less useful on:
Quality settings > Ironing > Enable ironing. Set to "Top surfaces only" to start.
Print settings > Infill > Ironing > Enable ironing.
Search "ironing" in settings (make sure All settings are shown). Enable "Iron top surface".
The percentage of normal extrusion used during the ironing pass. Lower flow means the nozzle is mostly just remelting existing plastic rather than adding new material.
How fast the nozzle moves during the ironing pass. Slower means more time for heat to transfer and flatten the surface.
How far apart the ironing passes are. Wider spacing is faster but leaves more texture. Tighter spacing is slower but smoother.
Most slicers offer concentric or linear options. Linear (back and forth) is the most common and works well for most shapes. Concentric follows the outer edge of the surface inward, which can look good on circular parts.
The best way is to print all four settings side by side using the Ironing Test at tools.print3dbuddy.com. It prints four flat tiles — one with no ironing as a baseline, then 10%, 15%, and 20% flow — so you can see the difference directly.
Otherwise, start at 15% flow and 50% speed, run a quick test tile, and adjust from there.
Still looks rough after ironing
Visible ridges or raised lines on the surface
Blobs or zits on the ironed surface
Ironing takes forever
For decorative prints, yes. The difference between an ironed and unironed flat top is immediately visible and gives prints a much more finished look.
For functional prints, it's usually not worth the time. A bracket or a tool holder doesn't need a polished top face.
The one thing to be aware of: ironing adds print time, sometimes significantly on large flat areas. Run it on the prints where it counts.
The Ironing Test at tools.print3dbuddy.com gives you all 4 tiles in one STL — no ironing, 10%, 15%, and 20% flow. Print them all at once, compare the tops, and you'll have your ideal setting in under 30 minutes.