What is warping in 3D printing?
Warping is the deformation of a 3D print caused by plastic cooling and shrinking unevenly. The bottom layers contract, building up tension and pulling the corners or edges away from the print bed. You’ll see this most often with large, flat prints and materials that shrink significantly, like ABS and ASA.
Plastic expands when heated and shrinks when it cools. An FDM printer lays down a layer of hot plastic onto a layer that is already cooling. Each new layer wants to shrink and pulls on the layer beneath it. The force is small per layer, but it accumulates until the print pulls harder than the bed adhesion can hold.
Corners are the weak point. That’s where the shrinkage forces from two sides meet. A long, straight edge ending in a sharp corner is therefore the classic victim of warping.
Warping is different from shrinkage. Every plastic shrinks a little, and as long as it happens at the same rate everywhere, your print will just be a fraction smaller. Warping only occurs when one area cools faster than another.
Where your print warps tells you the cause
Before you start tweaking settings, take a good look at where and when things go wrong. The pattern says a lot about the cause.
- All corners come loose during the first few layers. This almost always points to adhesion issues: a greasy bed, a nozzle that’s too high, or a bed that’s too cold.
- The corners only come loose after a few centimeters of height. The adhesion was fine, but the accumulated shrinkage tension became too great. Look into temperature, drafts, or the design itself.
- One side curls more than the other. High chance of drafts or cold air from one side, for example from a window, door, or air conditioning.
- The layers split open halfway through. The same shrinkage force, but between the layers instead of at the bottom. You see this mainly with ABS and ASA in a cold room.
Preventing warping: what actually works
The solutions below are roughly ordered from quick and free to more significant adjustments. Start at the top.
Start with a grease-free print bed
Fingerprints leave behind a thin layer of oil, which prevents filament from sticking properly. Wipe the bed down with isopropyl alcohol (90% or higher) before every print and avoid touching the surface afterward. Washing it once a week with water and dish soap will also remove stubborn residue.
If we had to point to the most overlooked cause, this is it. You can read about which type of bed works best for your filament in our article on print beds.
Stick to your filament's bed temperature
A heated bed keeps the bottom layers warm, which reduces the risk of shrinking. Use the value listed on your filament spool. For PLA this is usually between 55 and 65°C, and for PETG between 70 and 85°C. You can read more about why hotter isn't always better below.
Give the first layer time
A first layer that moves too fast won't have a chance to adhere properly. Set your first layer speed to 20 to 30 mm/s. Also, check that your bed is level, or let your printer auto-level if it has that feature.
Use a brim, mouse ears, or adhesive
A brim is a border a few millimeters wide around the first layer. It gives your print more grip on the bed, and the brim absorbs the pulling force instead of your corners. You can trim or cut it off afterward.
Is the problem only in the corners? Then mouse ears are more convenient: small, round discs a few layers thick, placed right under each corner. They require less cleanup than a full brim.
A thin layer of glue stick or adhesive spray also helps. It acts as a release layer, which reduces wear on your bed. Test it on a small print first, though, because too much adhesion can damage your print or your bed when you try to remove it.
Keep cooling low during the first few layers
The print fan blows cool air onto your print. This is great for overhangs, but disastrous for the first layers, which need to stay warm. Turn the fan off or keep it low for the first three to five layers. For ABS, ASA, and PC, you shouldn't be using the fan much anyway.
Keep drafts and cold air away from your printer
A printer placed by a window, in a hallway, or next to an air conditioner will constantly be hit by cold drafts. An unheated attic in winter is also asking for trouble. Place your printer in a quiet spot with a stable temperature.
Are you printing with ABS, ASA, PC or nylon? Then an enclosure is almost essential. It keeps the air around your print warm and still.
If you don't have an enclosure, enable a draft shield in your slicer. This is a thin, single-line wall that grows along with your model to trap warm air. Printing multiple objects at once also helps, as they retain each other's heat.
Choose a material that shrinks less
Not every filament shrinks at the same rate. PLA and PETG shrink very little and therefore rarely warp. ABS, ASA, PC, and nylon shrink significantly more and require a heated bed and a warm environment.
Fiber-reinforced filaments, such as carbon fiber nylon, are an interesting middle ground. The fibers inhibit shrinkage, making them more stable than the base material. If you're torn between two materials, our comparison of PLA and ABS will help you get started.
Design with warping in mind
Sometimes the solution isn't in the printer, but in the model itself. A few rules of thumb:
- Round off vertical corners. A rounded corner distributes stress, while a sharp corner concentrates it.
- Place the largest flat surface on the bed. More contact area means better grip.
- Avoid shapes that get wider towards the top. Every wider layer adds extra shrinkage force.
- Be extra careful with long, thin parts. They shrink along their entire length and are the most prone to curling.
In our guide on designing 3D models for 3D printing you can read about more design choices that make your print easier.
Let your print cool down on the plate
A print removed from the bed while warm cools unevenly and can still warp. Leave it attached until it reaches room temperature. This way, it cools down while the bed keeps it flat.
This doesn't work (or makes warping worse)
Turning the bed temperature up higher and higher
A warmer bed feels like the logical solution, but it only works up to a point. Are you already more than 15°C above your filament's recommended setting and your print is still curling? Then the problem lies elsewhere.
With PLA, a bed that is too hot actually works against you. Around 60°C, PLA starts to soften. The bottom layers become weak and bulge out (known as elephant's foot), while the layers above continue to shrink.
Pressing the first layer down extra hard
A nozzle that is slightly closer to the bed improves adhesion. Much closer does the opposite. The filament gets squashed, the bottom becomes rough, and you still end up with an elephant's foot. With PETG, the adhesion can become so strong that you might pull chunks out of your PEI sheet when removing the print.
PLA and PETG in a warm, enclosed housing
An enclosure is gold for ABS, but PLA and PETG actually need cooling. In a warm, enclosed cabinet, overhangs don't cool properly and your nozzle can clog because the heat creeps upward. Also, Prusa advises against an enclosure for PLA and PETG. Do you have a closed printer? Leave the door or lid open when printing with PLA.
100% infill for extra strength
More solid plastic means more plastic that shrinks, and therefore more pulling force on your corners. The strength of a print comes primarily from the walls, not from a solid interior. How much infill what you really need is often less than you think.
Drying filament as a solution for warping
Dry filament is always a good idea. Damp filament causes bubbles, stringing, and weaker layers. But moisture rarely explains curling corners. Have you dried your filament and the corners are still curling? Then take a look at your bed, your temperature, and the air around your printer.
Straightening a warped print afterwards
You can sometimes bend a slightly warped print back into shape with a heat gun. That might be fine for a decorative object, but not for a part that needs to fit precisely: the internal stress remains, the dimensions are no longer accurate, and the plastic can become weaker. By the way, that stress also makes a print less strong even if you don't see any warping. Reprinting after addressing the root cause is almost always the better choice.
Preventing warping in 7 steps
- Degrease your print bed with isopropyl alcohol.
- Check the bed temperature against the value on your filament spool.
- Print the first layer slowly, with the correct nozzle height.
- Turn the print fan off or low for the first few layers.
- Add a brim or mouse ears for large or angular prints.
- Keep drafts away, and use an enclosure for ABS, ASA, PC, and nylon.
- Let your print cool down completely before removing it from the plate.
Have you followed all seven steps and your print is still warping? Then the problem is often in the model itself: a sharp corner in the wrong place, a huge flat surface, or a shape that gets wider as it goes up. You don't always see that coming on your screen. Would you like someone to take a look with you before you start printing? Through the free printability check you will receive personal advice on your file, material, and settings within 48 hours.
Frequently asked questions about warping in 3D printing
Which filament warps the least?
PLA and PETG warp the least because they don't shrink much while cooling. Among technical materials, fiber-reinforced versions are more stable than their base materials. ABS, ASA, PC, and nylon are the most prone to warping, especially without an enclosure.
Can you straighten a warped 3D print?
Sometimes, using a heat gun or hair dryer. That works for objects that don't need to fit perfectly. For functional parts, dimensions and internal stress remain an issue, so reprinting is the better choice.
Does a brim always help against warping?
No. A brim gives your print more grip, but it doesn't eliminate the shrinkage force itself. If you print ABS in a cold, drafty room, a brim often just delays the problem. Temperature and environment are more important in that case.
Why does my PLA print warp if PLA is so easy to use?
Easy doesn't mean immune. Large flat prints, a cold room, drafts, a greasy bed, or a fan running at full power from the first layer can cause even PLA to warp. You'll notice this more often in the winter.
Can a 3D print warp after it's finished?
Yes. A print you remove from the bed while warm can still deform as it cools down. Heat can also warp a print later on: PLA starts to soften around 60°C, for example on a dashboard in the sun. You can read about which materials handle that better in our article on heat-resistant filament.
