The print lifts off the bed mid-print, slides around, or peels up from a corner while the rest keeps printing into the air. Sometimes it fails in the first 5 minutes; sometimes it holds through 2 hours then pops loose on a tall, heavy section.
Confirm This Is Adhesion, Not a Z-Offset Problem
Run your fingernail under the first layer after it prints. If you can slide it cleanly off the bed with almost no resistance, your Z-offset is too high — the nozzle never squished the filament down. That’s a calibration problem, not an adhesion problem, and cleaning the bed won’t help.
If the first layer looks well-bonded but the print lifts later, that’s a thermal or surface problem. They need different fixes.
The Most Common Cause Nobody Checks First
Fingerprints. One touch on a PEI sheet after a print leaves enough skin oil to ruin adhesion on the next print. Wipe with 90%+ isopropyl alcohol before every single print, even if you haven’t touched the surface. This fixes more “adhesion problems” than any settings change.
Fix Sequence
1. Clean the surface first. IPA wipe, let it dry fully. If it’s been weeks since you cleaned with soap and water (not just IPA), do a thorough wash — IPA redistributes oils over time without removing them.
2. Verify Z-offset squish. The first layer should look slightly wider than the line coming out of the nozzle, with edges touching the adjacent line. Distinct round lines that aren’t touching means Z-offset is too high.
3. Check bed temperature against material minimums. PLA: 60°C on smooth PEI, 55°C on textured. PETG: 75–80°C. ABS: 105°C. At 5°C below these values, adhesion drops sharply on anything larger than a business card.
4. Slow the first layer. 15–25mm/s gives the filament more contact time with the surface. Most slicers default to 30–40mm/s first layer, which is marginal for difficult materials.
5. Add a brim. For parts with small footprints or sharp corners, a 6–8mm brim adds enough contact area to survive the full print. Use it on anything with corners or under 30mm² base area.
Surface-Specific Notes
PEI sheet: Textured PEI is more forgiving than smooth — use textured as your default. For PETG on smooth PEI, increase Z-offset slightly and use a thin PVA glue stick layer as a release agent, or the part can fuse permanently to the surface.
Glass: Needs higher bed temps (5–10°C above PEI targets) and won’t release until cooled below 35°C. Don’t pull parts off warm glass. Hairspray on glass dramatically improves ABS adhesion.
BuildTak / Garolite: Better initial adhesion than PEI for Nylon and PP. Replace when you see deep gouges from the nozzle; worn BuildTak loses adhesion unpredictably.
What Doesn’t Work
Applying adhesive over an oily surface — you’re gluing on top of the problem. Glue stick on PEI for PLA usually makes adhesion worse, not better. Raising bed temperature above 65°C for PLA softens the already-printed layer and increases warping.