Image forming apparatus

An image forming apparatus comprising:

• an image former that forms an image on a recording material;
• a fixer comprising a first fixing member having an elastic layer, a second fixing member that forms a fixing nip with the first fixing member, and an external heater that heats the first fixing member from outside, the second fixing member having a second heater for heating the second fixing member to a temperature during normal printing such that the fixer fixes the image on the recording material by heating and pressing the conveyed recording material at the fixing nip;
• and
• a hardware processor that executes a thermal expansion mode,
• wherein in the thermal expansion mode, the hardware processor causes the external heater to heat the first fixing member to a temperature higher than the temperature during normal printing, and wherein the thermal expansion mode is executable during printing.