Whether it's pure cotton or a cotton blend, any clothing that contains cotton is susceptible to shrinking when subjected to heat. To prevent shrinking you should use the proper techniques -- cold water and low dryer heat settings -- and follow the care label -- take clothes labeled as dry-clean-only to the cleaners, for example. You can safely wash other cotton articles, either by hand or machine, so long as you do it properly. Be especially careful about drying, as the rapid drying of the cotton fibers is most likely to shrink them.
To wash cottons in your washing machine, set it to use cold water and to wash on the delicate cycle. Hot water shrinks cotton.
When the washing is over, line dry the clothes to prevent shrinking in the dryer. Reshape cotton sweaters and other delicates and dry them flat on top of the dryer or on a drying rack. If you want to dry your garments in the dryer, do so on a low or no-heat setting. Then take the garments out of the dryer and hang them before they are completely dry to help prevent both shrinking and wrinkles.
If you prefer to hand wash your cotton and cotton-blend clothes, do so in a clean sink or tub. Fill the sink with warm water and add some laundry soap made for hand washing. Place the cotton garments in the wash water, agitate them gently by hand and then allow them to soak for the amount of time indicated on the detergent packaging. This time will vary from one manufacturer to another.
To rinse the items, drain the tub and then refill it with cool water, agitating the garments by hand until soap bubbles no longer come out of them. You may need to repeat this process several times to remove all the soap.
Squeeze excess water out of the clothing but do not wring out the items, as this will cause wrinkling. After you've removed the excess water, line dry the garments, lay them flat to dry or place them in the dryer on a low or no-heat setting to prevent shrinking.