Almost every failed print shares one thing: the first layer didn’t stick. If that foundation fails, the print is already lost — everything above it depends on that single layer bonding to the bed. So when you’re chasing first layer adhesion problems, you’re really chasing the three things that break it: the nozzle sitting too high or too low, the bed temperature being wrong for your material, or the build surface being dirty or unsuitable.
This guide walks through each cause in the order that actually matters, with concrete numbers you can dial in. If you’d rather have the diagnosis handed to you, you can diagnose a failed print from a photo and get slicer-specific settings back — but the fundamentals below will fix the vast majority of cases.
Get the nozzle height (squish) right first
The distance between the nozzle and the plate decides how well the filament grabs. Too high, and the filament lands as round beads with barely any contact — it doesn’t really stick and gets knocked off easily. Too low, and the nozzle scrapes the bed and chokes normal extrusion. What you want is a first layer that looks slightly flattened and smooth, not round and not overly squished.
The margins here are brutal. Differences of 0.01–0.1 mm decide whether the first layer succeeds or fails. As a working gap, aim for roughly 0.06–0.2 mm from the bed — about the width of a sheet of paper — though the exact figure depends on your nozzle diameter and layer height.
Levelling vs Z-offset — they’re not the same thing
These get conflated constantly, and confusing them is why people fight their beds for weeks.
- Levelling (tramming): making the build plate parallel to the nozzle’s movement across it.
- Z-offset (zeroing): telling the printer where the build surface actually begins.
The technical levelling target is Z=0 — the nozzle exactly at the height of the bed. There’s no such thing as a 0 mm feeler gauge, of course, which is where the paper method comes in. But be aware: levelling from home with a sheet of paper raises your first layer height by the thickness of that paper, which is a common source of a slightly-too-high first layer. If you need a thicker first layer for a material like PETG, don’t fudge it with levelling — control it in the slicer via First Layer Height (e.g. change 0.20 mm to 0.28 mm).
One more thing that quietly ruins results: level warm. The bed expands slightly when heated, so levelling or measuring cold gives you inaccurate numbers.
Auto bed levelling doesn’t replace a good Z-offset
ABL probes multiple points, collects height data, and applies Z compensation while printing, making the nozzle-to-bed distance uniform across the surface. It’s excellent at compensating for a bed that isn’t perfectly flat — but it does not reliably nail the nozzle origin on its own. Contamination on the sensor tip or minor mechanical drift can shift results too.
The workflow that works: establish parallelism, apply mesh compensation, then dial in the Z-offset while watching your first-layer squish live.
First layer height and speed
For a standard 0.4 mm nozzle, keep layer heights between 25% and 80% of nozzle diameter. Go below 25% and you risk over-squishing and poor adhesion; exceed 80% and you get gaps and weaker parts.
A good starting first layer height for a 0.4 mm nozzle is 0.24–0.25 mm. A thicker first layer holds more heat energy, so it has more time to bond before cooling and is more forgiving of small imperfections in bed flatness. For PETG specifically, 0.28 mm helps stop the nozzle picking up strings of material.
Speed matters too. Print the first layer too fast and the filament doesn’t get the time it needs to bond to the bed, and it can detach almost immediately. Slow it to roughly 40–50% of your normal print speed. Suggested figures vary by source — anywhere from 30–50 mm/s down to a conservative cap of 15 mm/s — so treat it as a range and back it off if you’re still seeing lift.
Clean the bed — properly, every time
Fingerprints, dust and oils are the fastest way to ruin adhesion, and they’re invisible until the print curls off. Handle this before you touch any settings:
- General surfaces: wipe with isopropyl alcohol (IPA) before every print.
- Glass beds: window cleaner or dish soap and water work well.
- Stubborn residue: 100% acetone — but only if your bed supports it.
- PEI: clean with alcohol; avoid acetone on it.
- Glue or adhesive spray: apply a thin, even coat rather than layering fresh product over old residue.
Bed temperature by material
The wrong bed temperature undermines everything else. These are starting points — always verify against your filament’s data sheet.
- PLA: 50–60°C (some sources cite up to 65°C). It’s rare for standard PLA to need above 70°C.
- PETG: around 70°C as a starting point; sources differ, so treat it as a range and tune from there.
PLA and PETG behave very differently on the plate. PLA usually suffers from not sticking, while PETG often sticks too well and needs managing so you don’t tear chunks out of your build surface. We’ve written dedicated guides for each: first layer adhesion problems with PLA and first layer adhesion issues with PETG.
A sensible order of operations
- Clean the bed with IPA (or the right cleaner for your surface).
- Heat the bed to your material’s temperature and level warm.
- Set first layer height to ~0.24 mm (0.28 mm for PETG) in the slicer, not via levelling.
- Drop first layer speed to 40–50% of normal.
- Watch the first layer print and fine-tune Z-offset live for a slightly flattened, smooth line.
Work top to bottom and change one thing at a time. If you want the exact slicer values spelled out, see our guides on the best first layer settings in PrusaSlicer and OrcaSlicer first layer adhesion settings. For the broader picture, our roundup on how to get better first layer adhesion covers the checks that actually move the needle. Related: if you’re on PrusaSlicer, our guide to PrusaSlicer settings to fix first layer problems lists the exact values to change.
And if extrusion itself looks patchy — gaps, thin lines, missing material — that’s a separate problem worth ruling out with how to fix under-extrusion.
FAQ
What is the ideal first layer squish?
The first layer should look slightly flattened and smooth — not round beads (nozzle too high) and not scraped or gapped (nozzle too low). The workable gap is roughly 0.06–0.2 mm, and tolerances are tight: a difference of 0.01–0.1 mm can decide success or failure.
Does auto bed levelling fix adhesion problems on its own?
No. ABL compensates for an uneven bed surface, but it doesn’t reliably set your nozzle origin. You still need to dial in the Z-offset manually, and sensor contamination or mechanical drift can shift results. Establish parallelism, apply mesh compensation, then tune Z-offset by eye.
Why is my first layer slightly too high even after levelling?
Most likely the paper method. Levelling from home with a sheet of paper adds the paper’s thickness to your first layer height. Level warm, then fine-tune the Z-offset while watching the first layer print rather than trusting the paper gap alone.
Should I change my first layer height per material?
Yes — but do it in the slicer, not by re-levelling. Around 0.24 mm suits most materials on a 0.4 mm nozzle; bump PETG to 0.28 mm to stop the nozzle dragging strings. A thicker first layer holds heat longer and bonds more forgivingly.