If you’ve come from PLA, PETG breaks your instincts. The most common first layer adhesion issues with PETG aren’t about prints lifting off the bed — they’re about prints fusing to it so hard you chip the glass or tear the PEI coating getting them off. Then, on the same printer, the next print won’t stick at all. That paradox is exactly what trips people up, and it’s almost always down to two things: bed temperature sitting in the wrong place relative to the glass transition point, and a Z-offset copied straight from your PLA profile.

This guide gives you the real physics and the exact numbers to fix it. No hype, no copied-and-pasted “increase your bed temp” advice — just what actually works for PETG.

Why PETG First Layer Adhesion Behaves Differently

PETG has higher adhesion strength than PLA but needs more precision in bed preparation than ABS. Get it wrong in one direction and you get nothing on the bed; get it wrong in the other and you damage your build surface. That narrow window is the whole problem.

The single most important number is the glass transition temperature (Tg) — roughly 80°C (sources put it anywhere from ~75°C to 85°C). This is where the material starts to soften and lose its solid structure. The melting point is much higher, around 260°C, while the heat-deflection temperature — the point of deformation under load — is lower, around 70°C. Chemically, PETG is PET modified with cyclohexanedimethanol (CHDM) groups, which prevents crystallisation and lowers the melting point. That’s the background; the practical takeaway is that your bed temperature wants to sit right around the Tg. At that point the base of the print is soft and sticky enough to bond to the platform.

The second counter-intuitive trait: PETG prefers to be laid onto the bed, not squished into it. Almost every other material likes squish. PETG doesn’t. Raise your nozzle slightly so the first layer isn’t crushed flat, and adhesion actually improves.

Bed Temperature: Hotter Isn’t Always Better

The consensus working range is 70–90°C. Sensible starting points by surface:

  • Smooth or textured PEI: 70–80°C
  • Glass: 80–90°C (it needs more heat, but read the surfaces section below first)
  • General starting point: 80°C is a safe first guess for most setups

The biggest misconception in PETG troubleshooting is that more bed heat always means better adhesion. With PETG, overheating the bed is a genuine, common mistake. Too much heat makes the plastic squish out and stick too hard, turning removal into a risk to your bed surface. Don’t exceed the Tg by much — keep 90°C as a practical maximum. If you’re in a cold or draughty workshop, bump the bed by 5–10°C temporarily to compensate for the ambient, then drop it back.

Rule of thumb: if PETG won’t stick, you’re more likely too cold or your Z is too high than anything else. If it sticks too well and damages the bed, you’re too hot or your Z is too low.

Z-Offset: The Most Common PETG-Specific Culprit

This is where PLA habits do the most damage. PETG needs more gap than PLA — roughly 0.02 to 0.10 mm higher. PLA likes squish; PETG does not.

Read the extruded line:

  • Too low: the first layer looks smeared and translucent, and the nozzle ploughs through the plastic, causing it to glob onto the heater block rather than stay on the bed. This is why a too-low Z often reads as “won’t stick” — the material isn’t being laid down, it’s being dragged.
  • About right: the line has a slightly rounded top profile with visible layer lines. The first layer should look slightly squished, but not flattened out.

If you’re dialling in a fresh profile, our OrcaSlicer first layer adhesion settings and PrusaSlicer first-layer settings guides give you the exact values to start from — just remember to nudge the Z up from your PLA baseline rather than reusing it wholesale.

Bed Surfaces: Where PETG Causes Real Damage

PETG’s over-bonding makes surface choice and release agents non-negotiable.

Smooth PEI

The best all-rounder — but PETG can fuse to it and tear the coating. Use a thin, even layer of glue stick as a release agent, not an adhesive. It stops the plastic bonding permanently to the PEI. Counter-intuitive, but correct.

Textured PEI

Releases PETG more reliably than smooth PEI. Some PETG blends (and a few PLA silks) can still be stubborn, but this is the lowest-stress option for most makers.

Bare glass

Never print PETG on bare glass without a release agent. PETG bonds covalently to clean glass — people have genuinely torn chunks out of their glass bed pulling a print off. A glue stick or hairspray barrier is mandatory here.

BuildTak

Printing too close can permanently bond the PETG and the BuildTak surface together. Keep your Z honest and use the gap PETG wants.

A Quick Diagnostic Order for PETG First Layer Problems

  1. Won’t stick at all? Bed too cold (raise towards 80°C), Z too high, or — counter-intuitively — Z too low and globbing onto the nozzle. Check the first-layer line shape.
  2. Sticks too hard / damages the bed? Bed too hot (cap at 90°C), Z too low, or wrong surface for the job (bare glass, no release agent).
  3. Smeared, translucent first layer? Raise Z by 0.05 mm and re-test.
  4. Elephant’s foot at the base? Bed slightly too hot and/or Z too low — back both off a touch.

If you’d rather not eyeball it, upload a photo of the failed first layer to our Diagnose tool. It identifies the defect and returns slicer-specific settings — including downloadable .ini patches for PrusaSlicer and OrcaSlicer — instead of generic advice. If you want to understand the process first, our guide on how to diagnose a failed 3D print from a photo walks through it. And before you commit a long PETG print to the bed, run the file through our G-code checker to catch problems while they’re still cheap to fix.

FAQ

What bed temperature should I use for PETG first layers?

Start at 80°C for PEI, and 80–90°C for glass. Stay near the glass transition temperature (~80°C) and don’t exceed 90°C — too much heat makes PETG stick so hard it can damage your bed surface.

Why does my PETG stick too well and damage the bed?

Because PETG over-bonds. The bed is likely too hot, your Z-offset is too low, or you’re printing on a surface like bare glass or BuildTak without a release agent. Lower the bed temperature, raise the Z slightly, and use a glue stick as a release layer.

Why won’t my PETG first layer stick at all?

Usually the bed is too cold or the Z-offset is wrong. Note that a Z that’s too low can also fail to stick, because the nozzle ploughs through and globs PETG onto the heater block instead of laying it on the bed.

Should I squish the first layer like I do with PLA?

No. PETG wants to be laid onto the bed, not crushed into it. Set your Z-offset about 0.02–0.10 mm higher than your PLA value and aim for a slightly rounded first-layer line with visible layer lines.

Related: First Layer Adhesion Problems with PLA: The Real Causes and Exact Fixes