Warping: how to stop 3D prints curling and lifting

Short answer

The more a material shrinks, the more it warps. PLA almost never warps and PETG rarely does, while ABS, ASA and nylon want a hot bed and preferably an enclosure.

Warping: the short answer

Warping means the print bends and its corners lift off the bed. It happens because plastic shrinks as it cools: if the part cools unevenly, the cooler areas contract and pry the corners loose. The fix is always the same at heart: more even heat around the print and better grip on the bed.

Rule of thumb: The more a material shrinks, the more it warps. PLA almost never warps and PETG rarely does, while ABS, ASA and nylon want a hot bed and preferably an enclosure.

Why prints warp

When molten filament cools, it contracts. The bottom layers have time to cool while the upper ones are still warm, and the stress that builds up pulls the corners of the part upwards. Large, flat parts and high-shrinkage materials are hit hardest. Cold rooms and draughts make it worse because the cooling becomes even more uneven.

Fixes in the right order

1. Raise the bed temperature. A hot bed keeps the lowest layers soft so the stress cannot take hold. According to our data sheets, ABS and ASA want 90–110 °C and nylon 70–100 °C. If you are already at the top of the range and it still warps, the environment around the print is the next step.

2. Protect against draughts and keep the heat even. Place the printer out of any draught and keep the room temperature up. For ABS and ASA, an enclosure makes more difference than any other measure, because it keeps the air around the part evenly warm throughout the print. We go through how to set up the environment for each material in How to print ABS and How to print ASA.

3. Turn the fan off or keep it low. Layer cooling is designed for PLA. For materials that shrink a lot, the fan does more harm than good: turn it off or keep it below 20 percent for ABS, ASA and nylon. It also improves layer adhesion.

4. Improve the grip on the bed. A brim of 5 to 10 millimetres gives the corners much more contact area to hold on with. A glue stick strengthens the grip further. Also make sure the plate is clean and the first layer is pressed down properly, the same basics as in the guide on prints that won't stick.

5. Adapt the model. Sharp corners concentrate stress. Rounded corners in the model, or so-called mouse ears, meaning small discs added at the corners in the slicer, reduce the lifting force markedly. These are general tricks that designers have used for a long time.

How much do different materials warp?

The table ranks the materials in our range by how prone they are to warping, with the bed temperatures from our data sheets.

PLA Very low warping risk — bed 40–65 °C

TPU Very low warping risk — bed 25–75 °C

PETG Low warping risk — bed 50–70 °C

ASA High warping risk — bed 90–110 °C

ABS High warping risk — bed 90–110 °C

Nylon PA6-CF High warping risk — bed 70–100 °C

Would you rather avoid the problem?

If you would rather avoid the problem than solve it, the choice is simple: for parts that do not need heat resistance, PLA or PETG does the same job with no warping risk, a trade-off we discuss in PETG vs ABS.

Frequently asked questions about warping

Why does ABS warp so much?

ABS shrinks more than most other filaments as it cools, and that shrinkage is the driving force behind warping. That is why a hot bed (90–110 °C according to our data sheets) and an enclosure are essentially mandatory for larger ABS parts.

Can PLA warp?

It is unusual, but it does happen on large flat parts if the plate is dirty or the room is cold and draughty. The basics almost always suffice: a clean plate, correct levelling and a bed at around 60 °C.

Do hairspray or glue stick help against warping?

They increase the grip on the bed and help against mild warping, but they do not remove the cause. If the material shrinks strongly and the environment is cold, the corners will lift anyway, so always combine them with the right bed temperature and a draught-free space.

Why do layers crack higher up the part?

It is the same mechanism as warping, but between layers, often called delamination. Too much layer cooling or too low a nozzle temperature are the most common causes. Turn the fan off and raise the temperature slightly.