Printing liquids concentration

A method comprising:

• concentrating first printing liquid on a first developer roller;
• transferring the first printing liquid to a conveyor;
• further concentrating the first printing liquid on the conveyor using a first squeegee unit;
• concentrating second printing liquid on a second developer roller;
• transferring the second printing liquid to the conveyor, wherein the second printing liquid is transferred to on top of the first printing liquid;
• and
• further concentrating the second printing liquid on the conveyor using a second squeegee unit,
• wherein the first printing liquid transferred to the conveyor has a non-volatile solid concentration of at least 15%.

An apparatus comprising:

• a conveyor;
• a first developer unit to:
• concentrate first printing liquid, and
• deliver the first printing liquid to the conveyor;
• and
• a second developer unit to:
• concentrate second printing liquid, and
• deliver the second printing liquid to the conveyor to form a thick layer of printing liquid comprising the first and second printing liquid,
• wherein the thick layer of printing liquid has a thickness of at least 5 micrometers.