The print goes perfectly for the first twenty minutes. Then you glance at the bed and see that one corner has lifted by a millimetre — and the whole wall of the model has bent with it. That is warping: the most common and most frustrating problem in FDM printing.
The good news is that warping has a single physical cause and a handful of very concrete fixes. Below we explain where it comes from, which materials are most prone to it and what to do about it — from the simplest step to the most advanced.
What warping is and where it comes from
Plastic expands when heated and shrinks as it cools. In FDM printing the material is laid down layer by layer, so the lower layers cool while the upper ones are still hot. Every layer wants to shrink slightly more than the one beneath it, and that tension has to go somewhere.
It goes to the weakest point, and that is always the edge of the first layer. This is why corners lift first, and why large flat models are far harder to print than small tall ones.
A simple rule follows from this: either you fight the shrinkage itself by keeping the temperature around the print even, or you fight the peeling force by improving adhesion to the bed. Good settings do both at once.
Which filaments warp the most
| Material | Tendency to warp | What it means in practice |
|---|---|---|
| PLA, Hyper PLA, Silk PLA | low | a clean bed and 50–60 °C are usually enough |
| PLA/CF | low | carbon fibre noticeably limits shrinkage |
| PETG, Eco PETG | medium | sticks well, but likes a warmer bed |
| HT PETG | medium | higher temperatures, worth enclosing the printer |
| HIPS | medium | behaves much like a mild ABS |
| ABS, ABS/CF | high | without an enclosure large models almost always lift |
| ASA | high | like ABS, only more resistant to UV and weather |
| PC/ABS | high | needs a hot bed and a closed chamber |
| PA (nylon) | very high | on top of that it absorbs moisture from the air |
| TPU 98A, Easy Flex | very low | a flexible material releases the tension itself |
If you are just starting out and want to avoid the problem, stick with PLA. If you need strength, PETG is a sensible compromise between durability and ease of printing.
Ten ways to beat warping
1. Raise the bed temperature
The simplest and most effective step. A warm bed keeps the lower layers plastic, so they do not shrink abruptly. Raise it in 5 °C steps and watch the result — too high a temperature makes the first layers spread out instead.
2. Clean the bed with isopropyl alcohol
Grease from your fingers is the most common invisible cause of poor adhesion. Wipe the plate with IPA before every larger print and do not touch the surface where the model will stand.
3. Slow down and squash the first layer
The first layer should be printed at half the speed of the rest and pressed lightly into the bed — a flattened line has a larger contact area. A first layer height of 0.2–0.25 mm with a 0.4 mm nozzle is a safe starting point.
4. Turn the fan off for the first layers
Cooling is the enemy of adhesion. With PLA, switch the fan off for the first two or three layers; with ABS, ASA and PA keep it off or at a few percent for the whole print.
5. Add a 5–10 mm brim
A brim is an outline printed around the model in the first layer. It increases the bonded area exactly where the tension is greatest, and afterwards it comes off with a fingernail. With technical materials a brim is cheaper than a reprint.
6. Shield the print from draughts
An open window or air conditioning can ruin an ABS print in a quarter of an hour. A closed enclosure stabilises the temperature around the model and with ABS, ASA, PC/ABS and PA it is practically a condition of success. An improvised cardboard shield works too.
7. Check levelling and Z-offset
If the nozzle sits even 0.05 mm too high, the first layer only touches the bed instead of fusing into it. Re-level from scratch and print a first layer test — the lines should touch side by side, with no gaps.
8. Round the corners or add “mouse ears”
A sharp 90° corner concentrates all the tension in a single point. Rounding it with a 2–3 mm radius in the model spreads that force out. If you cannot change the geometry, add “mouse ears” — small flat discs in the corners, removed after printing.
9. Dry the filament
Damp material steams in the nozzle, the layers bond more weakly and the whole print is more prone to deformation. PA, PETG and TPU absorb water fastest. More in our guide to storing and drying filament.
10. Reach for adhesion promoters
A PVA glue stick, PVA diluted in water or hairspray create an intermediate layer that holds better than bare glass. A textured PEI plate handles most materials with no additives at all. For ABS, ABS juice also works well — filament scraps dissolved in acetone.
Starting temperatures
Below are starting points, not final settings — every printer and every colour behaves a little differently.
| Material | Nozzle °C | Bed °C |
|---|---|---|
| PLA, Hyper PLA | 200–230 | 50–60 |
| PETG, Eco PETG | 230–250 | 70–80 |
| HT PETG | 240–260 | 80–90 |
| ABS, ABS/CF | 240–260 | 90–110 |
| ASA | 250–270 | 90–110 |
| PC/ABS | 260–280 | 100–110 |
| PA | 250–270 | 70–90 |
| TPU 98A | 220–240 | 40–60 |
An honest note: the range for PLA comes from the print profile supplied by Porima. The remaining values are general starting ranges for each material group, not official manufacturer data — treat them as a point of departure and compare them with our temperature table and with the description of the specific product.
Design so that warping never gets a chance
Part of the problem is solved in CAD, before printing even starts. A large flat base is the worst possible case — if you can, split the model into smaller parts or rotate it so that it meets the bed with a smaller area. Thick, solid bodies shrink more than parts with 15–25 % infill, and abrupt changes in wall thickness create points where tension accumulates. Chamfers and fillets at the base are not only a matter of looks: they spread the peeling force over a longer distance.
With technical materials it is also worth remembering dimensional shrinkage. ABS and ASA shrink enough as they cool that fitted parts need it factored into their dimensions — ASA and ABS demand more patience here than PLA, but in return they offer temperature resistance PLA will never reach.
Frequently asked questions
Is a brim enough to print ABS without an enclosure?
With small models, usually yes. With parts whose base is more than a few centimetres across, a brim only delays the problem — what you need is a stable temperature around the print, which means an enclosure or at least a shield that limits draughts.
Raft or brim?
A brim in most cases. A raft uses more material and spoils the quality of the underside; it mainly makes sense on difficult bed surfaces or with parts that have a very small contact area.
My PLA lifts too — what am I doing wrong?
Most often it is a dirty bed or too high a Z-offset, not the material itself. Wash the plate with isopropyl alcohol, re-level from scratch and set the bed to 55–60 °C.
Does a higher nozzle temperature help against warping?
Indirectly. Hotter material bonds better to the layer below it, but it does not reduce the shrinkage itself — and overheating brings stringing and poorer detail. Fix the bed, the cooling and the adhesion first.
Why do large models lift more often than small ones?
Shrinkage is proportional to length. On a twenty centimetre wall the accumulated tension is many times greater than on a two centimetre one, while the point of support — the edge of the first layer — stays exactly the same.
If you are choosing a material for a specific job, take a look at our comparison of PLA and PETG and at the guide to PLA printing temperature.