A method of providing a printhead assembly having a hydrophilic ink pathway and a hydrophobic ink ejection face. The method includes the steps of: providing a printhead assembly comprising a printhead attached to an ink supply manifold, the printhead comprising a nozzle plate having a hydrophobic coating and a protective metal film disposed on the hydrophobic coating; treating surfaces of an ink pathway in the printhead assembly with a solution comprising an alkoxylated polyethyleneimine; drying the surfaces; and removing the protective metal film so as to reveal the hydrophobic coating.