
Casein, a protein found in milk, can be easily precipitated from standard moo juice with vinegar and turned into a malleable homemade plastic. Coffeebot wrote an Instructable that shows you how:
The final product is quite rigid when it’s thick (1/8 inch or thicker), moderately pliable when it’s a little thinner, and brittle if it’s paper thin. It’s also sandable and paintable.
I guess casein-based plastics used to be all the rage for buttons, jewelry and pens at the beginning of the 20th century.
Homemade Plastic From Milk [via MAKE]
See also: Moldable plastic from styrofoam

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According to a few things I’ve read, casein plastic will eventually decompose unless treated with formaldehyde or something similar because it’s basically just a concentrated clump of dairy protein. You’re basically just making really hard cheese here.
Plastic from Milk? I’ve always called it “Ricotta cheese” and not “plastic”…
))
I’m serious: if you put vinegar into hot milk you will get a soft cheese called Ricotta in Italy.
BTW, if you put vinegar into hot soy milk you will get Tofu (not as good as Ricotta)….
Plastic from Milk? I’ve always called it “Ricotta cheese” and not “plastic”…
))
I’m serious: if you put vinegar into hot milk you will get a soft cheese called Ricotta in Italy.
BTW, if you put vinegar into hot soy milk you will get Tofu (not as good as Ricotta)….
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