Which Fabrics Shrink the Most in the Wash? Does Washing or Drying Cause This?

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Author: Jennifer Penn-Chiu

Grade Level: 5th-7th; Type: Physical Science


In this experiment, we will discover which fabrics shrink the most in the wash and why. In theory, the fabrics should be expanded because of heat...but why do they shrink instead?

Research Questions:

  • Is there a way to prevent fabric shrinkage?
  • Do all fabrics, regardless of size, shrink the same percent of their total size?

Many people complain about their clothes shrinking in the wash. Many more complain, but much fewer know why this happens. Well, there are a few possibilities. It could be that the heat denatures the protein present in the fabric to cause shrinkage or that when fabrics are made, the fibers are stretched, but when heat is applied, they want to go back to their original state.


  1. Washer & Dryer
  2. Ruler
  3. Fabric of the Same Dimensions
  • 100% Cotton Fabric x 2 pieces
  • 100% Polyester Fabric x 2 pieces
  • 100% Rayon Fabric x 2 pieces
  • 100% Wool Fabric x 2 pieces
  • 100% Nylon Fabric x 2 pieces

Experimental Procedure:

  1. Take a ruler and measure the length and width of the fabrics before they are washed.
  2. Put the pieces of fabric in the washing machine and start the cycle to “warm”. Wait until the time is up (which is most likely 30-45 mins.)
  3. Take the pieces of fabric out. Check the dimensions again.
  4. Put one of each of the fabric samples into the dryer and let the other samples air-dry on a flat drying surface.
  5. Wait for the dryer to complete the cycle. Take the samples out and measure again.
  6. After the air-dried samples are done drying, take their dimensions.
  7. Is there any difference?
  8. Do some research to find out why certain fabrics shrink.


Suggested Chart



Initial Dimensions

After Wash

After Dried











































Terms/Concepts:  Fabric Shrinkage;  Protein denaturation; Properties of Heat; Properties of Water; Expansion/ Contraction


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