A build plate can look clean and still be covered with enough skin oil to ruin the first layer. Modern textured and smooth PEI surfaces are particularly good at showing this: one touched corner can fail while the rest of the print sticks perfectly.
Why fingerprints matter
Skin oil reduces surface energy and creates local areas where molten plastic does not wet the plate consistently. That is why random adhesion problems often follow where the plate was handled.
Routine cleaning
Remove loose debris and use the cleaning method recommended for your plate. For many removable PEI plates, warm water and a grease-cutting dish soap are effective for deeper cleaning. Rinse thoroughly and dry with a clean lint-free towel.
Isopropyl alcohol
IPA is convenient for quick wipe-downs, but it does not always remove a heavy grease film as effectively as washing. Use a clean cloth; wiping with an already contaminated rag can simply redistribute oil.
Do not use aggressive abrasives blindly
Some surfaces tolerate light conditioning, others can be damaged. Coated, patterned or specialty plates may have manufacturer-specific restrictions. Treat the plate type as part of the cleaning procedure.
Glue can be adhesion aid or release layer
On some material/plate combinations, glue is used not to make the part stick harder but to prevent excessive bonding and protect the surface. TPU and PETG are common examples where the role of glue can differ by plate.
When cleaning is not the root cause
If the entire first layer is consistently too high or too low, inspect probing, nozzle cleanliness and calibration. A dirty nozzle wiper can even affect automatic Z reference on some modern systems. See our nozzle-wiper guide.
Simple habit that prevents many failures
Handle removable plates by the edges, keep a dedicated clean cloth nearby and wash the plate whenever quick cleaning stops restoring reliable adhesion.
