The bed plate must be kept clean to assure good adherence of the filament for your first layer.

Clean your bed plate by washing with dish soap (Dawn works great!) and hot water and let air dry before returning to the bed. An occasional scrub using a clean ScotchBrite pad can help remove surface build up and oxidation of the PEI textured coating.

Don’t use alcohol as this just puts the greases and oils on the plate surface into solution, it doesn’t break them down or act as a surfactant, so they just slosh around and remain behind on the plate as you wipe. Don’t use cloths or towels to dry as they can contain conditioners and can leave micro fibers on the build plate resulting in poor adhesion.