Cotton sweaters can shrink when heat is used during the cleaning process. Hot water, steam and hot air can cause the new popular cotton manufacturing yarns to tighten into undesirable shapes when the cleaning process is not monitored closely. Garment manufacturers use a blocking process to ensure that each cotton sweater arrives at the store in a specified shape. It is easy to mimic this blocking process at home on all types of cotton clothing.
Wash the cotton sweater by hand or machine gently in warm water.
Lay a large, thick bath towel on the floor.
Arrange the damp cotton sweater on top of the towel in the desired shape. Gently pull and smooth the sweater fabric away from the centre of the garment in the direction that the sweater must be stretched.
Pin the sweater to the towel when the correct shape has been achieved. Add books or weights to the edges of the towel when necessary to keep your project straight.
Hold a clothing iron six inches above the garment. Use the steam function to mist the cotton sweater with heat to set the desired shape into the cotton fibres.
Cover the steamed sweater with a second towel while it is drying.
Iron the cotton sweater before it is removed from the towels after the garment is dry. Press a lightly heated iron down onto the top towel and lift it up quickly to prevent unwanted stretching during the ironing process.
Remove the top towel. Unfasten the pins. Wear your freshly stretched sweater.
Do not place a hot iron onto the sweater fabric.