US Patent 7914108 Image forming apparatus and method, and ink set

The image forming apparatus comprises: a treatment liquid deposition device which deposits treatment liquid onto a recording medium, the treatment liquid containing a polymerization initiator and particles introducing electrorheological properties; an electric field application device which applies an electric field to the treatment liquid having been deposited on the recording medium; an ink ejection device which ejects ink toward the recording medium on which the treatment liquid has been deposited, the ink containing a coloring material and a radiation-curable polymerizable compound; and a radiation irradiation device which irradiates radiation to cure the ink having been deposited on the recording medium.