First-layer failures are the single most common 3D printing problem, and thankfully the easiest to fix. This guide walks the 9 fixes in order from cheapest to most invasive — in practice, the first three solve about 80% of cases on Bambu, Prusa, Creality and any other FDM machine.
Wash the build plate with dish soap and water (not isopropyl — that smears oils around). Drop the first-layer speed to 20 mm/s . Verify your Z-offset by watching the first layer print: lines should be squished smooth , not stringy and not transparent. If you can still peel the print off easily after that, the plate needs more aggressive cleaning or a fresh nozzle.
Before you fix anything, calibrate what "good" looks like. Print any standard first-layer calibration square (most slicers ship one) and inspect:
Skin oils from one fingerprint are enough to break adhesion. A "brand new" sheet still has residue from packaging and manufacturing. Clean before every multi-day print and at the first sign of trouble.
It dissolves the PEI coating. Acetone is for ABS smoothing and glass beds only.
Z-offset (also called "live Z" on Prusa and "Z calibration" on Bambu) is the height of the nozzle above the bed for the first layer. Too high → lines don't stick. Too low → nozzle gouges the sheet and back-pressures the hotend.
Bed probes measure tilt and warp, not the gap between the nozzle and the bed. Your Z-offset is still the human-set "go this much lower than what the probe says" value. Bambu printers calibrate this every print but you can fine-tune it under Device → Cal → Vibration & Z offset .
Bed temperature controls how well the plastic bonds to the sheet. Too cold and the first layer never grabs; too hot and you get elephant's foot (the bottom layers squish out wider than the rest of the print).
The first layer is the one place where slow always beats fast. Modern slicer defaults aren't always conservative:
Beds move — thermal expansion, transport, even a hard print failure can tilt one corner. Run a mesh-bed-leveling pass any time you notice the first layer is good on one half of the plate and bad on the other.
A brim is a single-layer skirt that attaches to the print and dramatically increases the bed-contact area. It's the difference between a 30 cm² first layer and a 15 cm² one for tall, narrow prints.
Sheet surface and filament together dictate what adhesion aid (if any) you should use.
"Glue stick" means a Pritt-style PVA glue stick. Magigoo and 3DLac work too. A thin even layer beats a thick blotchy one every time.
If you've worked through everything above and still can't get adhesion, the hardware itself is suspect.