Bed Adhesion Guide: When You Need Glue and When You Don't

A print that lets go of the bed halfway through is the most common way to lose a spool's worth of filament and an evening. The fix usually isn't more glue — it's knowing which surface and filament combination actually needs it, and which ones do worse with it.

The Short Version: Plate Type Decides Almost Everything

Most bed adhesion advice online still assumes you're on bare glass or an aluminum bed, which is where the "always use glue stick" habit came from. Modern PEI-coated plates change the math. According to a 2026 bed-surface comparison from UAVMODEL, PEI "sticks to PLA and PETG at temperature, releases them automatically when the bed cools below 40°C, and requires zero adhesive" in the normal case — the exceptions are specific, not universal.

The same guide splits PEI into two finishes that behave differently:

• Textured PEI — PETG "releases cleanly... without any release agent," and PLA adhesion is described as slightly weaker than smooth PEI, with very small parts sometimes needing a brim.
• Smooth PEI — best suited to PLA, but PETG "can bond too aggressively... and tear the surface on removal," so a release agent (glue stick or Windex, per the same source) is recommended as a barrier layer specifically for PETG on smooth PEI.

That's the core rule worth remembering: on PEI, glue stick is usually acting as a release agent to protect the plate from PETG, not as an adhesion booster.

What Bambu Lab's Own Settings Table Says

Bambu Lab's official product page for its Textured PEI Plate publishes a materials table with a "Glue Stick Required?" column, which is about as direct a source as you'll get. Per that table:

• PLA / PLA-CF / PLA-GF: 45–60°C bed, no glue stick required
• PETG / PETG-CF: 60–80°C bed, no glue stick required
• TPU 85A/90A and 95A (AMS): 35–45°C bed, no glue stick required
• ABS (not A1 mini): 90–100°C bed, glue stick required
• ASA (not A1 mini): 90–100°C bed, glue stick required
• PC/PC-CF (not A1 mini): 90–110°C bed, glue stick required
• PA/PA-CF/PAHT-CF (not A1 mini): 90–110°C bed, glue stick required

That's a manufacturer's own guidance for one specific plate, and it lines up with the general pattern from the UAVMODEL comparison: standard PLA, PETG, and TPU are fine bare on a properly finished PEI surface, while high-shrinkage or high-temperature engineering filaments (ABS, ASA, PC, nylon) are the ones that consistently call for adhesive help. The plate's PEI coating is also listed at 0.075mm over a 0.5mm/0.4mm magnetic steel sheet, rated to 180°C surface temperature — worth knowing since it's a thin coating, not a thick one, and it's treated as a wear part rather than a permanent surface.

PETG Specifically Wants a Heated Bed and Sometimes a Barrier

Raise3D's PETG printing guide is blunt about the heated-bed requirement: PETG "requires a heated print bed to achieve reliable first layer adhesion and minimize warping," recommending a bed temperature in the 65–90°C range. The same guide notes that smooth surfaces like glass or PEI "can grip too tightly, so a release agent such as a glue stick or painter's tape is often necessary to protect the build plate" — which is the same protect-the-plate logic as the UAVMODEL piece, just from a different source.

Worth flagging: Bambu's own table lists PETG/PETG-CF as not requiring glue stick on its Textured PEI plate specifically. The apparent conflict isn't really a conflict — it comes down to smooth vs. textured PEI. Textured finishes tend to release PETG on their own; smooth ones are the ones where PETG welds itself to the coating. If your plate is smooth, treat PETG as needing a barrier. If it's textured, try it bare first.

Glass Plates Play by Different Rules

If you're on a glass bed rather than PEI, the calculus flips. UAVMODEL's comparison describes glass as giving "the flattest surface possible" with effectively unlimited lifespan if it isn't scratched or chipped, but notes it "requires a sacrificial adhesive layer for nearly every filament." PLA on bare glass is called "inconsistent" without hairspray or glue stick; PETG on bare glass is flagged directly — "do not do this," since PETG can rip chunks out of the glass surface on removal. TPU is described as working fine with a glue stick barrier since its flexibility lets it peel away even from a bonded surface.

Maintenance Actually Matters More Than People Think

Two maintenance details from the UAVMODEL comparison are easy to overlook:

1. Fingerprints cause real adhesion dead spots. Skin oils leave a film that blocks PLA from sticking to PEI in that exact spot — described as leaving "fingerprint-shaped adhesion failures" as the tell.
2. Isopropyl alcohol alone stops working over time. IPA dissolves oils but "just spreads them thinner" rather than removing them, so the guide recommends a warm water and dish soap wash every 10–20 prints (it specifically calls out unscented dish soap without moisturizers) to fully strip the residue that IPA wiping alone won't catch.

The same source estimates PEI sheet life at 6–12 months of regular use before adhesion degrades even with good cleaning, and notes BuildTak sheets typically last 3–6 months given how aggressively they grip.

What This Means Practically

If your printer shipped with a textured PEI plate — which covers most current Bambu, Prusa, Creality, and similar machines — start with nothing on PLA, PETG, and standard TPU, and only reach for adhesive if a specific print is actually failing to stick. Reserve glue stick, Magigoo, or a dedicated release agent for the filaments that consistently need it: ABS, ASA, PC, and nylon, per both the manufacturer table and the independent comparison above. If you're on a smooth PEI or glass bed, treat PETG as a special case that wants a barrier layer regardless of what you're printing otherwise. Wipe with IPA between prints, but don't assume that alone is doing the whole job — plan on an occasional soap-and-water wash of the plate itself.

None of this is a reason to throw out old adhesion habits developed on older printers — bare-aluminum and glass-bed machines are still common and still need the adhesive layer they always did. The point is just to match the method to your actual plate instead of applying a blanket rule that was written for a different generation of hardware.