PolyUrethane Stress Balls by Nicholas HOrtance

Stress is relatable to just about everyone and especially for college students. There are many ways to deal with stress but the easiest and most widely accessible way is to use a stress ball. This is why I purchased a very cheap watermelon stress ball.

Watermelon Stress Ball

Common Types

  1. In America the bean bag also known as "hacky sack" is the most popular type of stress ball
  2. Australia preferes foam ball
  3. China: developed the Baoding Ball typically used to improve motor skills


  • Foam Balls: Closed Cell Poly Urethane
  • Bean Bags: Dried Beans/PVC pellets/Expanded Polystyrene/or Expanded Polypropylene
  • Baoding Ball: Iron/Tungsten Carbide/Steel/Jade/Marble


The durometer is used to compare the density of particular materials on a hardness scale. It shows that polyurethane varies based on types of treatment, however standard foam balls are generally, easily indented.

Open Cell vs. Closed Cell

Polyurethane Formation

3-step reaction of polyurethane

Other Uses


  • http://www.thomasnet.com/articles/plastics-rubber/closed-cell-open-cell
  • http://www.energsmart.com/spray-foam-insulation/open-vs-closed-cell-foam.html


Created with images by pedro_santiago - "more stress balls" • mecookie - "Hercule Poirot Stress Ball"

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