Image forming apparatus and method of manufacturing printed material

A method of manufacturing a printed material using an image forming apparatus including

• a transport mechanism that transports a recording medium,
• a coating device that coats the recording medium with a pretreatment liquid,
• an ink jet head that jets an ink, and
• a processor that controls a transportation speed of the recording medium and a coating operation by the coating device in a case where an image is formed on the recording medium by jetting the ink from the ink jet head, the method comprising:
• receiving an input of an instruction to change the transportation speed by the processor;
• in a case in which a first transportation speed is designated as the transportation speed, transporting the recording medium at the first transportation speed by the transport mechanism, coating the recording medium with the pretreatment liquid by the coating device, and allowing the ink jetted from the ink jet head to adhere to the recording medium coated with the pretreatment liquid to form the image on the recording medium;
• in a case where a second transportation speed higher than the first transportation speed is designated as the transportation speed, transporting the recording medium, which is the same type of recording medium as that transported at the first transportation speed, at the second transportation speed by the transport mechanism, not coating the recording medium with the pretreatment liquid by the coating device, and allowing the ink jetted from the ink jet head to adhere to the recording medium not coated with the pretreatment liquid to form the image on the recording medium;
• and
• forming, on the recording medium transported at the second transportation speed, an image lower in print image quality than the image to be formed on the recording medium transported at the first transportation speed.