What appears to be a large piece of material dissolves in front of the audience’s eyes.


  • Water
  • Sugar or salt
  • Thinners, brush restorer or acetone
  • Thin pieces of expanded polystyrene, an expanded polystyrene cup, or expanded polystyrene “popcorn” from packaging.
  • Clear container


Dissolve something well known, such as salt or sugar, in some water. This is very familiar. Then, in a small amount of thinners, placed in a clear container before the demonstration, dissolve a large amount of expanded polystyrene. This can be especially effective if the piece appears to be a large one. Otherwise lots of popcorn may be dissolved in a little solvent.
(Note: The container in which this is done will have to be insoluble in thinners.)


This experiment relies on the solubility of different substances in different solvents. There will be some fizzing as the polystyrene dissolves. This is simply the gas that was used to expand the polystyrene. Expanded polystyrene is especially impressive as there is a large volume of solid that may be accommodated in a rather small volume of solvent.


This demonstration makes a big impact if something very familiar, like nail polish remover, can be used as the solvent. Do however be aware that such formulations contain increasing amounts of water, and that polystyrene is not soluble in formulations with too much water.


The vapours from acetone or similar solvents are harmful if inhaled for a long period of time or at high concentration. Ensure the room is well ventilated. Keep any open containers of solvents well away from sources of ignition. Be careful not to splash thinners on plastic items – they will dissolve.

Tags: dissolution, dissolve, acetone, polystyrene