Few settings change the quality of an FDM print as much as the surface you print on. Get the plate wrong and even the best spool warps, elephants or slides. Get it right — matched to your material and kept clean — and first layers become a non-issue. This guide explains when to reach for Cold PEI, Smooth PEI, textured PEI or glass.
What each surface does
| Surface | Key Trait | Great For | Avoid When |
|---|---|---|---|
| Cold PEI | Prints PLA/PETG at cool bed | PLA, PLA+, PETG quick workflows | ABS/ASA without a heated box |
| Smooth PEI | Flat, glossy mirror face | PLA/PETG flat-bottom neat parts | High-bed materials that like texture |
| Textured PEI | Dusted slightly speckled grip | PETG, ABS, ASA, TPU | When you need a VESA-glass flat bottom |
| Glass (PEO/coated) | Ultra-flat, shinier bottom | PLA, PETG flat mirrors, jigs | Materials prone to shatter-release stress |
On many Bambu Lab-family machines this is the "texture" choice hidden in the plate profile. Each surface grips by a different mechanism: Cold PEI uses a controllable, cool-bed adhesive layer that releases as it cools, smooth/top PEI grips hard on a flat face, textured PEI applies mechanical keying that sticks stubbornly while warm, and glass-family coated sheets give the flattest possible polished bottom surface.
Cold PEI: the low-temperature workhorse
Cold PEI is designed to print PLA, PLA+ and PETG with the bed at a moderate 45-60 °C rather than the 60-70 °C many profiles assume — meaning cooler prints, faster cooldown and parts that pop off on their own when the sheet reaches room temperature. If you print mostly PLA and PETG, a Cold PEI build plate is the simplest daily driver: texture-free smoothness, easy release, no brim surgery for most parts.
Cold PEI habits that keep it flat
- Start PLA around 0.08-0.12 mm first layer height at 45-55 °C bed and check the skirt is a single pressed-on ribbon.
- Let the whole plate cool to near room temperature before flexing parts, so they fall rather than tear.
- For PETG, keep bed a touch warmer (~60 °C) and drop the part after a slow cool to avoid yanking the top layer of PETG off itself.
Smooth and textured PEI: when you need more grip
A Smooth PEI sheet yields a near-mirror flat bottom for display parts. Textured PEI adds a fine matte grain and clamps down on higher-temperature plastics — PETG, ABS and ASA stick reliably while warm and let go cleanly as the plate cools. The right rule is simple: want a smooth bottom with cool PLA in front of you → smooth or cold PEI; printing hot, sticky or easy-to-warp materials → textured PEI.
Keep PEI sticky
- Wash with a rinse after handling — skin oil is the #1 reason adhesion dies.
- Don't scrape with metal; use a plastic spatula or flex the sheet off.
- If a spot refuses to release, cool the bed fully, then flex from a corner — never pry the middle.
Glass-family plates: the most polished foot
Coated glass-family sheets give the flattest face and a glossy bottom finish, popular for jigs, mirrors and photo-style parts. PLA and PETG behave well; PETG on some coated glass sticks so well it can chip or pull glass when pried — release while the bed is fully cold and only from an edge. Keep glass cleaner than PEI because any speck shows as an empty first-layer spot.
Bulletproof cleaning, whichever sheet
The surface you print on is only as good as its cleanliness. Whatever the spool, adhesion fails first through contamination:
| Contaminant | Where From | Fix |
|---|---|---|
| Skin oils and grease | Handling the plate | Warm water + a rinse; avoid fingerprinting the centre |
| PETG/TPU residue residue build-up | Repeated same-area prints | IPA/soap cycle, then a cool re-dry |
| Old glue-stick or paint flecks | Cleaning compounds left over | Strip and start clean; avoid abrasive scrubs on coated sheets |
| Dust / fuzzy particles | Open-air printing | Lint-free wipe right before the first layer |
A clean, matched plate beat extra glue and brims every time. If a print keeps lifting after you fix orientation and temperature, the answer is usually a dirtier hidden face or a sheet whose coating has worn thin in its busy zone.
Match your plate to your material
| Primary Material | Try First | Tip |
|---|---|---|
| PLA / PLA+ | Cold PEI | 45-55 °C, pop off when cool |
| PETG | Smooth PEI or textured | Cool fully before release |
| ABS / ASA | Textured PEI | Warm, enclosed, release after cool |
| TPU | Textured or Cold PEI | Low speed, avoid prying |
| Flat cosmetic foot | Glass / smooth top | Keep spotless |
The best build-plate strategy is a small quiver: Cold PEI for everyday PLA and PETG, Smooth PEI for glossy bottoms, and a textured or glass sheet for the jobs that really demand it. Keep each clean and let the plate cool before release, and the first layer stops being a fight.
Build plates and full spools are at innostation3d.net.