Before ironing a sweater, you should be ready to open the shelf of the sweater, because when ironing a sweater, it will expand with heat and contract with cold at a certain high temperature, so to ensure that the size of the sweater will not change, you must have a hanger. In addition, the temperature should not be too high. Generally, sweaters should be ironed with a steam iron to ensure a certain degree of wetness when ironing.