Science project

Removing Wrinkles From Polyester

Research Questions

  • Why do polyester garments become wrinkled?
  • What are the physical processes that counteract wrinkling?

Polyester fabrics become wrinkled during a washing machine’s spin cycle if they are washed in hot water during the regular wash cycle. If a permanent press washing cycle is used, however, the clothes are cooled before they enter the spinning cycle. This reduces wrinkling.

In the regular dryer cycle, the temperature remains high throughout the drying process. In the case of the permanent press dryer cycle, the temperature starts out high, then decreases to a cool-down temperature. This reduces wrinkling.  

Polyester fabrics undergo a change in physical properties at a characteristic temperature known as the glass transition temperature. Below about 70 deg C, the long chain-like molecules in polyester fabrics become locked in place. Above this temperature, the bonds that hold the chain molecules in place break, and the molecules are free to move around. If the temperature is decreased to below 70 deg C, bonds again form between the molecules that hold them in place.


  • Polyester garment (avoid wrinkle-free fabric), washing machine, dryer, clothes steamer
  • Materials can be found at home and are readily available.

Experimental Procedure:

  1. Familiarize yourself with the physical properties of polyester fabrics, and the heat characteristics of washing machine and dryer cycles.
  2. Wash a polyester garment in a washing machine using the regular wash cycle. Then dry it in a clothes dryer using the regular cycle. This should maximize wrinkling.
  3. Formulate a hypothesis to explain why the garment became wrinkled.
  4. Place the garment in the washing machine again and wash it using the regular wash cycle. Then hang it on a clothesline to dry. Observe the amount of wrinkling.
  5. Place the garment in the washing machine and wash it using the regular wash cycle. Dry it using the regular cycle.
  6. Spray the garment with a light mist of water. Then cover the wrinkled garment with a pressing cloth and iron it. Observe the amount of wrinkling.
  7. Wash the garment using the permanent press cycle and then dry it using the permanent press setting. Remove the garment from the dryer when the cycle is finished, and hang it. Observe the amount of wrinkling.
  8. Repeat these steps with another polyester garment
  9. Evaluate your hypothesis in light of your findings. If necessary, revise it and conduct additional tests.
Amount of wrinkling
Garment 1
Regular wash/dry cycle only
Permanent press (wash/dry)
Garment 2
Regular wash/dry cycle only
Permanent press (wash/dry)


Terms/Concepts: Polyester; Glass transition temperature; Wrinkling


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