First layer won't stick to the bed

Symptom

When the print starts, the plastic doesn't stay on the bed: lines drag, curl up or stick to the nozzle, or the part comes loose shortly after starting. Sometimes it only fails on some areas of the bed.

Likely causes, from most to least likely

1. Dirty or greasy print surface: a few fingerprints or residue from earlier prints are enough to stop the plastic from gripping.
2. Nozzle too high on the first layer (Z offset): the line lands round, not squished, and doesn't bond to the bed or to the neighbouring lines.
3. Bed or nozzle temperatures that don't suit the material, or the wrong material or build surface profile selected in the slicer.
4. First layer printed too fast: the plastic has no time to grip.
5. Part with a small footprint, or a material that needs a thin layer of glue stick on that surface.
6. Partially clogged nozzle: little plastic comes out and the lines are thin and weak.

Checks to tell which one it is

• Inspect the surface for fingerprints, grease stains or leftovers from earlier prints, especially where the plastic doesn't grip.
• Look at the first-layer lines: round lines with gaps between them mean the nozzle is too high; flat, almost see-through lines or ridges mean it is too low.
• Compare bed and nozzle temperatures with the material profile and make sure the slicer has the build surface you actually have installed.
• Purge some filament: if it comes out thin, in spurts or curls around the tip, suspect a partial clog.
• Check whether it fails across the whole bed or only in one area: a specific area points to levelling rather than cleaning.

Before you start

Before taking anything apart, cleaning or adjusting it, switch the printer off and unplug it, unless a step says otherwise, and do not touch the nozzle, the heater block or the bed until they have cooled down. If in any doubt about electricity, heat or moving parts, stop and ask a professional.

Step-by-step fix

1. Clean the surface while it is cold

   With the bed cold, wipe it with unscented paper towel and isopropyl alcohol of at least 90% (cosmetic-grade alcohol contains oils and won't do). On smooth PEI sheets, if that isn't enough, wash it with warm water and a few drops of dish soap. Never use acetone on textured or satin sheets.

   Check: The surface looks even and the next first layer sticks across the whole part.

   If that does not fix it: Check the first-layer height in the next step.

2. Adjust the first-layer height

   Use your printer's first-layer calibration or fine Z adjustment (Live Adjust Z, babystepping or Z offset) and lower the nozzle gradually until the lines come out slightly squished and joined together. Don't lower it too far to make up for poor adhesion: the nozzle can damage the surface.

   Check: Lines are flat, with no gaps between them and no ridges.

   If that does not fix it: If some areas look right and others don't, the problem is levelling or the mesh: check bed levelling.

3. Use the material profile temperatures

   Print with the temperatures the slicer profile suggests for that material and surface. If a new material won't stick, Prusa suggests raising the bed by 5-10 °C as a starting point.

   Check: Edges and corners stay down during the first layers.

   If that does not fix it: Slow down the first layers.

4. Print the first layers slower

   Reduce first-layer speed in the slicer, or from the printer screen during the print. As a guideline, Prusa suggests dropping to about 75% for the first three layers and then going back to normal speed.

   Check: Lines settle without dragging or lifting in curves.

   If that does not fix it: Add a brim to the part.

5. Add a brim

   Enable a brim in the slicer to increase the first-layer contact area, especially for small, tall or narrow-based parts.

   Check: The brim stays down and holds the part until the end.

   If that does not fix it: Try a thin layer of glue stick.

6. Apply a thin layer of glue stick

   With the bed cold, spread a very thin layer of glue stick (PVA) only over the print area. On smooth PEI it is recommended for PETG, ABS, ASA, PC, nylon and flexibles; it isn't needed for PLA.

   Check: The first layer grips and the part releases well once cooled.

   If that does not fix it: Check that the nozzle is extruding normally.

7. Rule out a partial clog

   If the purged filament comes out thin, in spurts or curls around the tip, treat the nozzle as clogged (push fresh filament by hand, thin needle or cold pull) before adjusting the first layer any further.

   Check: Filament comes out straight, steady and at its normal thickness.

   If that does not fix it: If nothing works, the surface may be worn out: ask your printer manufacturer whether it should be renewed or the sheet replaced.

Prevention

• Don't touch the print surface with your fingers or dirty tools: then you won't need to clean it before every print.
• Redo the first-layer calibration after changing the sheet or nozzle and after moving the printer.
• Always start from the slicer's material profiles.

Still not fixed?

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Printers it applies to

Any FDM (filament) 3D printer, from any brand.

Official sources

This guide summarises the official documentation linked here:

• First layer issues · Prusa Research
• Print surface preparation · Prusa Research
• First Layer Calibration (i3) · Prusa Research