Layer separation, also called delamination, is what happens when the layers of a print split apart along the layer lines. The part cracks, peels, or zips open at a seam, instead of holding as one solid piece. Per Prusa’s layer-separation guide, the cause is almost always poor bonding between layers, from a nozzle that runs too cold or layers laid too tall.
The split weakens the part, so it fails under load even if it looks fine at first glance. Work the causes in order and reprint the same test after each fix.
Your material sets the risk. ABS and ASA separate the most, PETG and nylon separate when they are wet, and PLA holds its layers best.
Likely causes, ranked
| Likely cause | Fix | Severity |
|---|---|---|
| Nozzle temp too low | Raise the nozzle 5 to 10 C so each layer bonds to the one below. | hi |
| Layer height too tall | Lower the layer height so the layers press together more. | md |
| Cooling too high | Cut part cooling for materials like ABS that need heat to bond. | md |
| Poor adhesion from wet filament | Dry the spool, then reprint. Wet filament bonds weakly. | md |
| Printing too fast | Slow the print so each layer has time to fuse. | lo |
Fast fixes to try first
Print a small part and try to split it by hand, then work top to bottom and reprint after each step.
Raise the nozzle temp
Add 5 to 10 C and reprint so each layer fuses to the last.
Lower the layer height
Drop the layer height a step and reprint for tighter bonding.
Cut the cooling
For ABS and ASA, reduce part cooling so the layers stay hot and bond.
Dry the filament
If the layers look rough or pop, dry the spool and reprint.
If the quick fixes stall
When temp and layer height do not end the split, the print setup is the next place to look.
Slow the print
Drop the speed so each layer spends more time hot against the last.
Add an enclosure
For ABS and ASA, an enclosure holds the heat in so the layers do not cool too fast.
Widen the extrusion width
A slightly wider line presses the layers together harder for a stronger bond.
What your material changes
ABS and ASA shrink as they cool, so they pull apart at the layers unless the chamber stays warm. PETG and nylon bond well when they are dry, but a wet spool weakens the bond and invites a split. PLA holds its layers the best, because it prints cool and sticks to itself easily.
Habits that backfire
A few common choices trade the split for a new problem.
Avoiddo not
- Raising the temp so far the filament degrades or strings.
- Leaving part cooling high on ABS or ASA, which kills the bond.
- Printing tall layers to save time, which weakens every seam.
- Skipping the dry step for PETG or nylon.
Key takeaways
- Layer separation splits a print along the layer lines from weak bonding.
- Raise the nozzle temp 5 to 10 C and lower the layer height first.
- Cut cooling and add an enclosure for ABS and ASA.
- Dry PETG and nylon. Wet filament bonds weakly.
For related problems, the under-extrusion guide covers thin walls that can read as weak layers, and the filament storage guide covers keeping spools dry.
Related guides
Related
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Cross-reference
Sources & methodology
2 citations · reviewed 2026-07-10- 01Prusa Knowledge Base: Layer separation and splittingaccessed 2026-07-09Tier 1
- 02All3DP: Delamination and layer separation tipsaccessed 2026-07-09Tier 2