LAYER SEPARATION (DELAMINATION)
Cracks between layers, prints that snap along layer lines - delamination is a thermal fusion failure. Fix temperature, cooling and layer height to bond layers properly.
⚡ 10–25 minintermediatehigh confidencelayer adhesiondelaminationtemperature
Quick Fixes
Raise nozzle temp 5-10C
Reduce part cooling fan (PETG 30-50%, ABS 0-30%)
Dry filament if you hear popping
Layer height max 75% of nozzle (0.3 mm on 0.4 nozzle)
Lower print speed by 10-20 mm/s
WHY THIS HAPPENS
Layers bond by thermal fusion. When a fresh layer is deposited on top of the previous one, the heat in the new plastic re-melts the surface of the layer below. Polymer chains from both layers intermix at the boundary, then solidify into a continuous fused mass as everything cools. If that re-melt doesn't happen, the new layer just sits on top of the old one with no chemical bond and almost no mechanical bond.
Four things suppress thermal fusion. Low nozzle temperature delivers plastic that isn't hot enough to re-melt the previous layer. Excessive cooling chills the previous layer's surface so completely that even hot fresh plastic can't re-soften it. High print speed reduces the dwell time the new layer has to fuse before more layers pile on top. Tall layer heights reduce the contact area between adjacent layers - a 0.32 mm layer on a 0.4 mm nozzle has only ~70% of the contact pressure of a 0.2 mm layer.
Moisture is a hidden multiplier. Water in filament boils to steam in the nozzle and creates microscopic voids in every layer. Those voids are crack-initiation points. A part that should have 80 MPa interlayer strength might have 30 MPa with wet filament - structurally fine for a vase, structurally useless for a bracket.
WHEN THESE FIXES FAIL
**If you can see clear gaps between layers in the print** - severe under-temperature or layer height too tall.
**If the print looks fine but snaps along layer lines under stress** - moderate under-temperature, excessive cooling or moisture.
**If popping sounds during printing** - moisture. Dry the filament and retry.
**If the issue only happens with high cooling settings (PETG, ABS at high fan)** - reduce fan first.
**If layer separation only happens at certain heights** - usually where the model has thin walls or single perimeters. The thinner the wall, the more vulnerable to weak fusion.
**If layer separation appeared after switching to a new spool of the same brand/type** - filament quality or moisture. Try drying first; if that fails, the spool may be defective.
MOST LIKELY CAUSES
1
Nozzle temperature too low
high confidence
Layers do not bond properly if filament is not hot enough to fuse into the previous layer.
→ Raise nozzle temperature by 5-10C
→ Run a temperature tower to confirm the bonding range
→ Use the hottest clean-printing temperature within the safe range
2
Cooling too strong
high confidence
Excess cooling chills each layer before the next layer can fuse to it.
→ Reduce part cooling fan speed
→ Use 30-50% fan for PETG-style profiles instead of 100%
→ Use 0-30% fan for ABS/ASA-style profiles
3
Layer height too tall
medium confidence
Tall layers have less contact area and weaker pressure between layers.
→ Keep layer height at or below 75% of nozzle diameter
→ Use 0.16-0.24 mm layer height with a 0.4 mm nozzle
→ Lower print speed by 10-20 mm/s
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Generate SettingsWhat It Looks Like
Visible gaps or cracks between layers, or prints that snap cleanly along a layer line with very little force.
Why It Happens
Layers bond by thermal fusion. When a fresh layer is deposited on top of the previous one, the heat in the new plastic re-melts the surface of the layer below. Polymer chains from both layers intermix at the boundary, then solidify into a continuous fused mass as everything cools. If that re-melt doesn't happen, the new layer just sits on top of the old one with no chemical bond and almost no mechanical bond.
Four things suppress thermal fusion. Low nozzle temperature delivers plastic that isn't hot enough to re-melt the previous layer. Excessive cooling chills the previous layer's surface so completely that even hot fresh plastic can't re-soften it. High print speed reduces the dwell time the new layer has to fuse before more layers pile on top. Tall layer heights reduce the contact area between adjacent layers - a 0.32 mm layer on a 0.4 mm nozzle has only ~70% of the contact pressure of a 0.2 mm layer.
Moisture is a hidden multiplier. Water in filament boils to steam in the nozzle and creates microscopic voids in every layer. Those voids are crack-initiation points. A part that should have 80 MPa interlayer strength might have 30 MPa with wet filament - structurally fine for a vase, structurally useless for a bracket.
What The Community Data Says
Based on 174 confirmed fixes from r/FixMyPrint, these are the causes ranked by how often they actually worked:
1. Nozzle temperature too low - raising 5-10C above current was the most common single fix. Many users were running at the bottom of the manufacturer's range and didn't realise their hotend reads cold.
2. Cooling fan too high - dropping fan from 100% to 30-50% on PETG, or 0-20% on ABS, fixed cases where users had cranked up cooling for stringing reasons.
3. Wet filament - drying solved cases where temperature changes alone didn't help. Wet filament delaminates regardless of how hot you run.
4. Layer height too tall relative to nozzle - going from 0.32 mm to 0.2 mm on a 0.4 mm nozzle restored interlayer bonding.
5. Print speed too high - dropping 10-20 mm/s gave layers more time to bond before the next layer arrived.
Data sourced from r/FixMyPrint - one of the largest 3D printing troubleshooting communities on Reddit. This represents real user-reported issues and community-confirmed fixes, not theoretical advice.
How To Diagnose Your Specific Cause
If you can see clear gaps between layers in the print - severe under-temperature or layer height too tall.
If the print looks fine but snaps along layer lines under stress - moderate under-temperature, excessive cooling or moisture.
If popping sounds during printing - moisture. Dry the filament and retry.
If the issue only happens with high cooling settings (PETG, ABS at high fan) - reduce fan first.
If layer separation only happens at certain heights - usually where the model has thin walls or single perimeters. The thinner the wall, the more vulnerable to weak fusion.
If layer separation appeared after switching to a new spool of the same brand/type - filament quality or moisture. Try drying first; if that fails, the spool may be defective.
Fixes By Cause
Cause 1: Raise nozzle temperature
Increase 5-10C and reprint. PLA: bring to 210-220C. PETG: 240-250C. ABS: 250-260C. ASA: 245-255C. PC: 270-290C. The higher the temperature within the safe range, the better the interlayer bond. Don't fear running PLA at 220C - layer adhesion improves significantly without major stringing penalty if Pressure Advance is calibrated.
Cause 2: Reduce part cooling fan
PETG: 30-50% (not 100%). ABS/ASA: 0-30% maximum. PC: 0%. PLA: keep 100% but watch for delamination on tall thin walls - drop to 60-80% there. Fan-induced delamination is most common when users copy PLA fan settings to PETG/ABS profiles.
Cause 3: Dry filament
PLA 45-50C / 4-6 hrs. PETG 55-65C / 4-6 hrs. ABS 60-80C / 4-6 hrs. Nylon 70-80C / 8-12 hrs. PC 80-90C / 8-12 hrs. Test after 2 hours - if popping has stopped and surface quality improved, drying is fixing it.
Cause 4: Reduce layer height
Maximum reliable layer height = 75% of nozzle diameter. 0.4 mm nozzle: 0.3 mm max. 0.6 mm nozzle: 0.45 mm max. Drop to 0.2 mm if delamination persists - the safest layer height for a 0.4 mm nozzle is 0.16-0.24 mm.
Cause 5: Reduce print speed
Drop print speed 10-20 mm/s and retest. Slower printing means more time for fresh plastic to fuse with the previous layer before being chilled by the moving fan or covered by the next layer.
Printer-Specific Notes
Bowden printers (Ender 3 family): Stock thermistors can read 5-10C high, meaning your 'PLA at 210C' is actually 200-205C. If layer separation appears at recommended temperatures, raise 10C. Replacing the thermistor with a quality genuine part fixes the underlying inaccuracy.
Direct drive printers (Bambu, Prusa MK4S): Thermistors are usually accurate. Layer separation here is more often caused by wet filament or excessive cooling than under-temperature.
Enclosed printers (Bambu P1S, K1 Max): Chamber heat improves interlayer bonding for ABS/ASA dramatically. If you're delaminating ABS in a P1S, check the door is closed and the chamber has come to ~35-45C before the print.
Filament-Specific Notes
PLA / PLA+: Strongest interlayer bonds among common filaments. Delamination is rare unless temperatures are wrong or filament is severely degraded.
PETG: Generally strong interlayer but very sensitive to fan speed. Run fan at 30-50% maximum. Print at 240-245C for best bonding.
ABS / ASA: Weak interlayer in open air, strong in enclosure. Delamination on these filaments without an enclosure is normal - don't try to fix it with settings, build an enclosure.
TPU: Bonds well but soft - 'delamination' on TPU usually means under-extrusion. Diagnose extrusion first.
Nylon / PC / PA-CF: Hygroscopic and delaminate readily if not dried. Always dry before printing. Print in an enclosure for best results.
How To Prevent It Next Time
Set part cooling fan presets per filament family in your slicer profiles. PLA 100%, PETG 40%, ABS 0-20%, never copy PLA cooling to other materials.
Keep all engineering filaments (PETG, ABS, nylon, PC) in dry boxes between uses. The strength loss from moisture is invisible until your part snaps in service.
For functional parts, prefer 0.2 mm layer height even if you can technically go thicker. The strength benefit per gram of plastic is significant.
Get An Exact Fix For Your Setup
Use FixMyPrint to get nozzle temperature, fan speed, layer height and print speed values tuned for your specific printer and filament - based on what actually worked for similar issues in the community.
Go to /settings-generator to generate yours.
Recommended Slicer Settings
Related Guides
Under-Extrusion (Gaps, Thin Walls, Missing Lines)
Gaps in walls, thin lines, missing infill - under-extrusion has five common causes. Diagnose which one applies to your print and fix only that one.
⚡ 15–45 minintermediatehigh confidenceunder extrusionclogs
Warping and Corner Lifting
Corners curling up off the bed mid-print? Warping is differential cooling shrinkage. Fix it with bed temperature, brim, enclosure and adhesion.
⚡ 10–25 minbeginnerhigh confidencewarpingadhesion
Weak or Sagging Overhangs
Overhangs sagging, curling up, or printing as fuzzy strings? This is a cooling and speed problem. Maximize cooling, slow overhangs, and reorient where possible.
⚡ 5–15 minbeginnerhigh confidenceoverhangscooling
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