Glossary · Build plate

3D printing

PEI

A plastic with two roles: as a coating on print plates it makes prints stick well. As a printing material it is an extremely heat-resistant specialist plastic.

Explained in more detail

Polyetherimide, trade name Ultem. As a build plate coating (smooth or textured), PEI gives good adhesion with a warm bed, and parts usually release by themselves after cooling. As a filament, PEI is a high-performance plastic with printing temperatures of around 350 to 400 °C, a glass transition at about 215 °C and very good flame resistance; it can only be processed on industrial printers.

Where does the term come from?

PEI stands for polyetherimide, named after the ether and imide groups in the chain. The trade name Ultem comes from General Electric, and the brand now belongs to SABIC.

In practice

• Smooth PEI plates give a smooth, slightly glossy underside, textured ones a matt one, and they are considered more robust.
• For a quick clean in between, isopropyl alcohol of at least 90 % on a lint-free cloth is enough; washing-up liquid with warm water cleans more thoroughly.
• Fingerprints and grease are the most common reason why the first layer suddenly stops adhering.
• PETG, some TPU types and PC stick too strongly to smooth PEI; a thin film of glue stick acts as a release layer.
• Use acetone only if the manufacturer allows it, as it is usually not intended for textured plates.

Not to be confused

If you search for PEI in a shop, you will find build plates and filament. PEI filament (Ultem) cannot be printed on home printers.

Frequently asked questions

How do I clean a PEI print plate?

In between with isopropyl alcohol, thoroughly with washing-up liquid and warm water, then dry well. Acetone only if the manufacturer approves it.

Why does my print not come off the PEI plate?

Usually the plate is still too warm or the material sticks too strongly to smooth PEI. Let it cool, and with PETG, TPU or PC use glue stick as a release layer in future.