Accidentally ironed creases can be very stubborn. Even after a few passes with the hot iron, clear creases still remain.

 

Take an ice cube and rub it back and forth on the crease. When the crease is damp, you can run the iron over it. The creases will disappear quickly and easily.

 

You can also quickly make a creased jumper wearable again by wrapping an ice cube in a thin cloth and rubbing it over the creased areas of the jumper. Then iron over it and the jumper will look as good as new again.