When even PLA won't stick
PLA is the most forgiving filament to lay down, so when its first layer lifts or looks gappy, the fault is rarely the plastic. It is usually mechanical: the nozzle starts too high, the bed is not level, or the bed is too cool to hold the corners.
Why PLA lifts
A bed that is too cool or too hot, a first layer that is printed too fast or too high, and cooling that kicks in too early all hurt PLA adhesion. Polymaker's PLA printing data gives the temperature ranges for a clean first layer.
Nozzle, bed and cooling settings
Each value below is from Polymaker's PLA material page.
- Nozzle temperature — use 190–230 °C for standard PLA (lower than ABS or PETG). (Polymaker PLA guide)
- Bed temperature — set it to 40–60 °C; heating is optional but recommended for best adhesion. (Polymaker PLA guide)
- Cooling fan — run it at 100 % for sharp details, which also keeps overhangs and bridges clean. (Polymaker PLA guide)
Checking adhesion
Print a 75 mm one-layer square, let it cool, then try to pull the lines apart with a fingernail. A good PLA first layer comes up as one sheet with the lines fused and no gaps. If lines separate, lower the nozzle or raise the bed within 40–60 °C. If the corners still peel, level the bed before you change any temperature, and let a full print finish to confirm it holds.