“Potato plastic” experiment

How to make plastic from a potato

Pota­toes are very rich in starch–a poly­mer of veg­etable ori­gin, which we use very of­ten in ev­ery­day life. To­day we’ll show you how to make a neat toy from starch!

Safe­ty pre­cau­tions

Ob­serve safe­ty rules when work­ing with flame and heat­ed ob­jects. Don’t taste the toy.

Warn­ing! Only un­der adults su­per­vi­sion.

Reagents and equip­ment:

  • pota­to;
  • grater;
  • wa­ter;
  • fun­nel;
  • gauze (or med­i­cal ban­dage);
  • beakers;
  • heat­ing de­vice;
  • any food col­or­ing (not oblig­a­tory);
  • stick;
  • glass con­tain­er;
  • cit­ric acid (or any oth­er acid, for ex­am­ple vine­gar);
  • glyc­erol;
  • bak­ing mold of your choice.

Step-by-step in­struc­tions

Grate the pota­to fine­ly, and add a small amount of wa­ter (200 ml) to the pota­to, to rinse as much starch away as pos­si­ble, and stir. Then put the mix­ture through a fun­nel with gauze, to sep­a­rate the juice from the starch.

Af­ter a few min­utes, when the starch has set­tled, drain the juice. To the sed­i­ment add 30 ml of wa­ter and stir, and pour the so­lu­tion into a clean beaker. Add a few drops of food col­or­ing and 30 ml of a 5% cit­ric acid so­lu­tion, and 15 ml of glyc­erol.

Then, con­stant­ly stir­ring, heat the so­lu­tion, with­out let­ting it boil. Over time the so­lu­tion will thick­en con­sid­er­ably, and then be­come liq­uid again. Pour it into the ice cube mold and leave it at room tem­per­a­ture for 3 hours.

Pro­cess­es de­scrip­tion

Acid caus­es the branched struc­ture of starch to break down. It turns into long chains and be­comes elas­tic. When the so­lu­tion cools, these chains be­come dense­ly stacked to­geth­er, turn­ing into a dense mass. The evap­o­ra­tion of wa­ter also as­sists the for­ma­tion of dense ma­te­ri­al.

When glyc­erol is added the toy does not crack, as the glyc­erol mol­e­cules fit be­tween the starch mol­e­cules, main­tain­ing its elas­tic state – the toy does not crum­ble like short­bread.