Last updated: October 19, 2026

Why your 3D print corners lift (and how to fix warping)

You start a print, the first layers look great, and an hour later one corner is curling up off the bed like a potato chip. That's called warping. It's very common, and in most cases it's fixed with a few simple habits.

Why warping happens

Melted plastic shrinks a little as it cools. Each new layer cools on top of the layer below and pulls on it slightly. Across a whole print, those small pulls add up, and they're strongest at sharp corners and on long, flat parts. If the first layer isn't holding on firmly enough, the corners peel up.

So there are two ways to win: make the print stick better, and reduce how quickly or unevenly it cools. Prusa's own guide to warping describes it the same way: the goal is to reduce the "thermal shock" the plastic gets as it goes from the hot nozzle to the cooler room.

Material matters a lot. PLA and PETG shrink very little, so warping with them usually means an adhesion problem. ABS, ASA and polycarbonate shrink much more and are known for warping, especially on large parts.

Step 1: Clean the build plate

This fixes more warping than any setting. Skin oils from your fingers stop plastic from gripping the plate. Wash the plate with warm water and a drop of dish soap, rinse, dry, and then hold it by the edges. Wiping with isopropyl alcohol (Prusa recommends 90% or stronger) works well between washes. Always check your printer maker's care instructions for special coatings.

Step 2: Get the first layer right

If the nozzle is a little too high, the first layer just sits on the plate instead of being pressed onto it, and corners lift easily. You want lines that are slightly flattened and touching each other, with no gaps. Our bed leveling and first layer guide shows exactly what to look for and how to adjust the Z offset (the nozzle's height above the bed).

Don't overdo it: Prusa warns against "over-squishing" the first layer, and with PETG, too much squish can make it bond so strongly it damages a smooth PEI plate.

Step 3: Use the right bed temperature

Use the bed temperature printed on your filament spool, or your slicer's profile for that material. As a rough guide, PLA usually prints on a bed of about 50 to 60 °C and PETG at about 70 to 85 °C. Not sure which filament to use? See PLA vs PETG for beginners.

Going a few degrees warmer, within the spool's range, can help a stubborn corner. Going far above the range usually doesn't help and can make the bottom of PLA prints soft and bulging (often called "elephant's foot").

Step 4: Block drafts

Cool air hitting one side of a print makes that side shrink faster. That's why warping often happens on the corner nearest a window, door or fan. Move the printer away from open windows, air conditioning, heater vents and ceiling fans. Even a cardboard box or a folding screen placed nearby (not touching the printer) can help.

Step 5: Add a brim or "mouse ears"

A brim is a flat border of extra lines around the bottom of the print. It gives the print a much bigger grip on the plate, holding the corners down while it cools, and snaps or peels off afterwards. It's a simple checkbox or dropdown in most slicers (the program that prepares your model).

If you don't want a full brim, add small, thin discs at just the corners. People call them "mouse ears". Prusa suggests the same idea: a small, few-layers-tall shape added to the problem area.

Step 6: Leave the cooling fan settings alone (mostly)

Your slicer's default profiles usually keep the part cooling fan off or low for the first layer or two, then turn it up. For PLA and PETG that's right: they need cooling for clean detail. If you've been changing fan settings, go back to the default profile. For ABS and ASA, profiles use little or no fan, because fast cooling makes them warp more.

Step 7: Enclosures are for ABS and ASA, not PLA

An enclosure keeps the air around the print warm and still, which is exactly what high-shrink materials like ABS, ASA and polycarbonate need. Prusa notes that printing PLA or PETG inside an enclosure may not be a good idea, because they need plenty of cooling and a warm box makes that harder. If you print PLA in an enclosed printer, leave the door or lid open as your printer maker recommends.

Step 8: Change the design if you can

• Round the corners. Sharp corners warp more than rounded ones.
• Split huge flat parts into smaller pieces where possible.
• Lower the infill (the internal fill pattern) on big flat parts; less plastic means less pulling.

What about glue stick and hairspray?

A thin layer of glue stick, applied to a cold plate, can help adhesion on smooth plates and protects some surfaces. Hairspray works on glass beds, but avoid spraying near the printer's moving parts. Many modern textured PEI plates grip PLA well with nothing on them, so try a really thorough clean first.

Quick reference

Your next step

If you haven't already, run through the first print checklist. It builds plate cleaning and first-layer checks into every print, which prevents most warping before it starts. Did a curled corner knock your print sideways part-way up? See how to fix layer shifting.