Reducing contamination

A method for maintaining print quality of images printed with a liquid electrophotographic printing apparatus, the method comprising:

• purifying an imaging oil by:
• filtering the imaging oil through an imaging oil filter;
• and
• then filtering the imaging oil through a polar absorbent filter, thereby forming a purified imaging oil;
• detecting that a contamination level of the purified imaging oil ranges from 0 pico Ohms/cm up to 10 pico Ohms/cm;
• applying the purified imaging oil to an amorphous silicon photoconductor of the liquid electrophotographic printing apparatus prior to a charging portion of a print cycle to remove residue from the amorphous silicon photoconductor, thereby forming a contaminated imaging oil;
• and
• removing the contaminated imaging oil from the amorphous silicon photoconductor.

A liquid electrophotographic printing apparatus, comprising:

• an amorphous silicon photoconductor;
• a cleaning station to periodically apply a purified imaging oil to the amorphous silicon photoconductor and to remove contaminated imaging oil from the amorphous silicon photoconductor;
• and
• a recycling unit in fluid communication with the cleaning station, the recycling unit including:
• a first compartment to receive the contaminated imaging oil from the cleaning station, the contaminated imaging oil including printing fluid particles and polar molecules;
• an imaging oil filter to receive the contaminated imaging oil from the first compartment and to remove at least some of the printing fluid particles to form a filtered imaging oil;
• a second compartment to receive the filtered imaging oil from the imaging oil filter;
• and
• a polar absorbent filter to receive the filtered imaging oil from the second compartment and to remove the polar molecules to form the purified imaging oil.