Clothing can shrink when dried in a dryer but not when hung outside to air-dry due to differences in the drying processes and the effects of heat on fabric fibers.
1. Heat and Agitation in the Dryer: When you put clothing in a dryer, it is exposed to heat, and the tumbling action can create friction between the fabric fibers. The combination of heat and agitation can cause the fibers to contract and tighten, leading to the fabric's shrinkage.
2. Evaporation of Water: In a dryer, the water in the clothing evaporates rapidly due to the high heat and air circulation. As the water evaporates, it leaves gaps between the fibers, and when the fibers cool down and contract, the gaps result in shrinkage.
3. Gentle Drying with Air-Drying: When you hang clothing outside to air-dry, there is no heat or agitation involved in the drying process. The fabric fibers are allowed to dry gradually through evaporation, but without the rapid evaporation caused by the high heat of a dryer. The fibers retain their natural state, and the chances of shrinkage are minimized.
4. Fabric Type and Care: The type of fabric also plays a significant role in shrinkage. Natural fibers like cotton and wool are more prone to shrinking because of their cellulosic or protein-based structure. Synthetic fibers like polyester are generally more resistant to shrinkage. However, even natural fibers can be treated and processed to minimize shrinkage, which is why reading and following the care instructions on clothing labels is essential.
5. Overdrying: Overdrying clothing in the dryer can also contribute to shrinkage. It is best to remove clothing from the dryer while they are still slightly damp and let them finish drying naturally. This can help prevent excessive shrinkage.
To summarize, clothing shrinks in the dryer due to the combination of heat, agitation, and rapid evaporation of water, which causes the fabric fibers to contract. When hung outside to air-dry, the absence of heat and gentle drying through evaporation helps maintain the fabric's original size and shape. Choosing the appropriate drying method based on the fabric type and following proper care instructions can help minimize shrinkage and extend the life of your clothes.