Ironing in 3D printing: how the top surface is smoothed

How ironing works

The top surface is printed from adjacent lines, between which fine grooves remain. In ironing the nozzle passes over the finished surface once more at the same height, pressing the heat-softened plastic and filling the gaps. The setting is described in the OrcaSlicer wiki and in the Prusa knowledge base.

It works only on top surfaces that are flat or nearly flat. On walls and on rounded parts it does nothing.

The cost of ironing

Printing takes longer on parts with a large flat top, because the nozzle goes over every top surface again slowly and with a small step. That is why it is used only where the result is visible, for example on a lid, a plaque or a surface with text. At a layer height of 0.2 mm the difference between a top with and without ironing is visible mainly when viewed at an angle.

What ironing does not solve

• Sloped or rounded surfaces, where the steps between layers stay visible.
• Poor flow or too high a temperature, which give a rough top even without ironing.

When ironing is worth it. Ironing makes sense on large flat surfaces that you look at or touch: hatches, plaques, the top of a box, labels. On a surface that is never seen, it is wasted time. On a small part with a few millimetres of top, ironing adds almost nothing. Ironing is done on a fully continuous base, see top and bottom layers.

Ironing in your order

Ironing is not an option in the calculator and we do not use it as a special service. We choose these settings ourselves according to the model and material. In the calculator you choose the material, infill strength, scale and number of pieces, and the rest is in the price. If you need a very smooth surface, leave the top of the part flat and you can sand it yourself after printing. That procedure is for information only, as we do not offer sanding.