Making Plastic Milk

Plastic Milk???
In a Grimm’s fairy tale, Rumplestiltskin turned straw into gold. Although not as lucrative a venture, you can try your hand at changing things by turning milk into PLASTIC! Start with a glass of milk; add a “secret ingredient” and voila! Solid, soft, mouldable plastic.
What do you need?
1 cup whole milk
Small saucepan
Measuring spoons
White vinegar (acetic acid)
Empty glass jar (cleaned)
Wax paper
What do you do?
Pour the milk into the saucepan and add 2 teaspoons of vinegar. Heat the solution over medium heat while stirring frequently. The milk will boil and being to form tiny lumps (called curds) in a clear liquid (known as whey…is the Little Miss Muffet rhyme sounding a bit familiar right now?).
Slowly pour off the liquid from the saucepan into the sink, and then spoon the curds into the jar.
Next, add 1 teaspoon of vinegar to the curds and let the mixture stand for about one or two hours. The curds will form a yellowy blob at the bottom of a clear liquid. The blob is actually fat, minerals and the protein called casein (milk protein).
After the incubation step, pour out the liquid and remove the rubbery yellow blob from the jar.
Wash the glob with water and knead it until it gets the consistency of dough.
Now’s your chance to show off the artist in you: Mould the plastic into any shape you wish, then place it on the wax paper and let it dry overnight to harden.
Want to take your artsy skills even further? The hardened plastic can be painted with acrylic paints, so go nuts and give your creation some colour!
Page 1 …fill your mind.THE LAB
The Explanation
The combination of heat and vinegar (acetic acid) causes the casein from the milk to clump together and come out of solution (i.e. precipitate). Casein is an ingredient used in making plastic which is why the blob resembles plastic. This casein plastic hardens when the curds dry out.
Don’t underestimate the importance of what you’ve just done…casein plastics were commonly used to make glue, paints, and paper.
Here are some neat facts about Casein plastic…

• Casein plastic was one of the first plastics ever made

• The first plastics were developed in 1862

• Casein was discovered in the 1890’s by a German inventor, Adolph Spitteler

• Casein was used in England to produce: glues, pens, knife handles, and buttons.