First layer won’t stick: causes and fixes

Before buying a new plate, try washing it. In most cases adhesion drops not because the coating is worn but because of skin oils — and it comes back after an ordinary wash with dish soap.

Why grease is to blame

A PEI coating holds the part thanks to the micro-texture of its surface. A thin film of grease fills that texture — and adhesion is gone. Touching the print surface with your fingers a few times is enough.

Isopropyl alcohol, which people often wipe the bed with, removes glue residue and dust well but does a poor job on grease. That’s why “I wiped it with alcohol and it still won’t stick” is so common.

How to wash a textured PEI plate — the manufacturer’s way

1. Remove the plate from the printer.
2. Wash it with an ordinary sponge and dish soap — it works as a degreaser.
3. Scrub the surface so the soap gets into the texture rather than just gliding over the peaks.
4. Rinse with warm water.
5. Dry it with a paper towel.

Two important warnings

• The soap must not contain oils or moisturisers — they stay on the plate and reduce adhesion themselves. Check the label: anything “with balm”, “with glycerin” or “hand care” won’t do.
• Don’t clean a textured PEI plate with acetone — it damages the coating.

How to check the plate is clean

A simple test from the manufacturer: pour water over the surface. If it spreads as an even, continuous film, the plate is clean and will hold well. If the water beads up, there’s still grease — wash it again.

Other causes of a bad first layer

• Calibration. After replacing the nozzle, hotend or plate, always recalibrate the printer.
• The wrong plate for the material. Different coatings are designed for different plastics — check the manufacturer’s compatibility table.
• Mechanical damage. Spatula scratches and bare patches don’t recover — that really is a reason to replace the plate.
• A difficult material. ABS, ASA and nylon often need a glue stick even on a clean plate.
• A draught in the room. Sudden cooling makes the part lift at the corners — especially with high-shrinkage materials.

The opposite problem

Sometimes it’s the other way round: the part sticks so hard it risks tearing off a piece of the coating. Most often it’s PETG on a smooth PEI plate. In that case a thin layer of glue stick acts not as an adhesive but as a release layer.

What you may need: PEI build plates, glues and adhesives.