Polyester fabric is one of mankind's great inventions -- it's stain resistant, wrinkle resistant and water resistant. On the downside, it's super durability also makes it shrink resistant, which can be a major headache if you're trying to resize clothes such as a cotton/polyester-blend sweatshirt. Cotton is natural cellulose material, which is susceptible to shrinkage when exposed to heat. Although polyester is not a cellulose, water temperatures exceeding 176 degrees Fahrenheit can alter the chemistry of this man-made material and force it to shrink.

Machine Wash on Shrink

Step 1

Load the sweatshirt into a washing machine. Read the garment care labels of any other garments you plan to wash with the sweatshirt to ensure that they can be safely washed with hot water.

Step 2

Adjust the washing machine's temperature setting to hot -- the heat will naturally shrink the cotton fibers in the sweatshirt but will have little effect on the polyester. Run the washing machine through a full cycle.

Step 3

Transfer the garment to the dryer and add your preferred fabric softener. Adjust the dryer to it's highest temperature setting and dry the sweatshirt for no less than 15 minutes. The heat in the dryer will further shrink both the cotton and polyester fibers in the sweatshirt.

Step 4

Remove the sweatshirt from the dryer and inspect it for shrinkage. Return the garment to the dryer for an additional 15 to 20 minutes if it has not adequately shrunk. Let the garment air-dry if it shrank to an acceptable size.

Boiled Down to Size

Step 1

Fill a large cooking pot with 2 gallons of hot water and place it on the stove. Use enough hot water for the sweatshirt to move freely.

Step 2

Rinse the garment in warm water until it is wet throughout. Wring out the excess water and place the sweatshirt in the pot.

Step 3

Heat the water on the stove to boiling; the water must be hotter than 176 degrees Fahrenheit to disrupt the polymer bonds in polyester and make them shrink.

Step 4

Boil the sweatshirt for 15 to 20 minutes. Use tongs and heat-resistant rubber gloves to periodically check the progression of the sweatshirt's shrinkage.

Step 5

Carefully transfer the sweatshirt from the pot to a sink or tub and let it cool for 10 minutes. Use rubber gloves to wring out the excess water and then load it in the dryer with your preferred fabric softener.

Step 6

Dry the sweatshirt on the dryer's highest temperature setting. Remove the sweatshirt from the dryer after 20 minutes and inspect it for shrinkage. Dry for an additional 20 minutes to shrink more or let it air-dry if the desired size has been achieved.