Some fabrics shrink in the dryer, and it is always useful to know which ones will shrink before you toss them in the dryer. That favorite pair of cotton blue jeans or your prized wool sweater may never fit again if they shrink in the dryer. If there is more than one fabric on a piece of clothing, such as two sections of a skirt, one part may shrink and the other may not. Read the labels on your clothing before you throw anything in the dryer, so you will know if it is going to shrink or not.
Cotton can shrink up to 20 percent every time it is put in the dryer. Although many believe that it is the heat of the dryer that causes the shrinkage, according to Cotton Incorporated, that is not actually the case. The tumbling of the dryer evaporates moisture from cotton clothing, causing it to shrink.
Testing by Cotton Incorporated shows that cotton clothing that is tumbled dry in a dryer at various heats (100, 150 and 200 degrees Fahrenheit) all showed the same amount of shrinkage. Clothes that were dried at higher heats shrank faster than those at the lower heat.
Hemp garments that are washed in hot water or put into the dryer will shrink. The natural fibers of the material will physically shrink, making the garment smaller. The fact that hemp will shrink is important to remember when you are thinking of its similarity in appearance to linen and the softness of the fabric. The material is also three times as strong as cotton fibers and takes fabric dye easily.
When wool is washed, the natural fibers of the fabric tend to stick together, making the garment appear smaller. If you lay the garment flat and pin it to an underlying board in the proper shape, the fibers will begin to dry out and the garment will return to its original size.
When a wool garment is placed in the dryer, the fibers set with the heat of the dryer and the shrinkage becomes permanent. Once the garment has been washed and dried in the dryer, there is no way to return it to its proper shape.