Ironing is a slicer feature that runs the hot nozzle over the top surface of a print after completing the normal top layers, at a very slow speed with minimal extrusion. The nozzle heat slightly remelts and flattens the top surface, filling micro-gaps between extrusion lines and producing a noticeably smoother finish than the standard top surface pattern. It’s one of the highest-value quality improvements available as a single slicer toggle.
How Ironing Works
After printing the final top surface layer normally, the slicer generates an additional pass across the entire top surface. The nozzle moves at 10-15% of normal print speed (very slowly) with extrusion set to approximately 10-15% of normal flow. The combination of slow movement, residual nozzle heat, and minimal fresh plastic remelts the surface lines into a smooth, near-glossy plane.
The result is a top surface that looks and feels distinctly different from the normal textured top layer. On a flat lid like a deck box cap, the improvement is immediately obvious in both appearance and tactile feel. The surface looks machined rather than printed.
When to Use Ironing
Ironing works best on large flat horizontal surfaces like lid tops, flat panels, and any face that will be highly visible from above. It doesn’t improve vertical walls or curved surfaces. Enable it for deck box caps, flat prop panels, and display bases where the top face is the primary visible surface. The time cost is 10-20% per top surface area ironed, which is worthwhile for a deck box lid but unnecessary for a fully enclosed structural box body.
In Bambu Studio: Quality settings, then enable Ironing. The default ironing settings work well for standard PLA without adjustment. More on slicer quality settings at the PLA settings reference.
Frequently Asked Questions: Ironing in 3D Printing
What does ironing do in 3D printing?
It smooths the top surface of a print by running the hot nozzle over it slowly with minimal extrusion after the normal top layers are complete. The nozzle heat remelts and flattens the surface, producing a noticeably smoother finish than the standard top layer pattern.
Does ironing work on all filament types?
Yes, for any thermoplastic FDM material. The ironing temperature uses the same nozzle temperature as the print, so no special settings are needed. Results are best on flat surfaces. On textured or matte filaments, the improvement is still visible but the finish remains matte rather than producing a gloss.
Does ironing slow down printing significantly?
It adds time proportional to the top surface area being ironed. For a flat lid (100 x 75mm), ironing adds 5-15 minutes. For a small accessory with limited top surface, it adds 1-3 minutes. Only meaningful for large flat top surfaces.
