Printheads of all types have historically had a difficult time keeping contamination from entering their apertures during the printhead maintanence cycle. This is due to a negative pressure at the aperture that must be maintained for jetting performance. The current study examined this problem analytically and experimentally. It has demonstrated that maintaining a low pressure during the entire printhead maintenance cycle almost completely eliminates this problem. Results are applicable to most ink-based printing technologies, and will improve print quality and reliability.