Department of Energy Argonne National Laboratory Office of Science NEWTON's Homepage NEWTON's Homepage
NEWTON, Ask A Scientist!
NEWTON Home Page NEWTON Teachers Visit Our Archives Ask A Question How To Ask A Question Question of the Week Our Expert Scientists Volunteer at NEWTON! Frequently Asked Questions Referencing NEWTON About NEWTON About Ask A Scientist Education At Argonne Milk Plastic
Name:  N Alexander C.
Status: other
Age: 18
Location: N/A
Country: N/A
Date: 2000

Hi Recently I warmed up some milk in a saucer and then poured some vinegar in it. I filtered the fat out of it and shaped it into a ball. I let it sit for a couple of days and it turned into plastic.

Will you explain what reaction took place and why?

N Alexander,

You precipitated the casein (a protein) out of the milk by effect of the acid (vinegar) and heat. Acids denature and coagulate proteins. The plastic-like substance you obtained was very likely rather sticky. In fact, in bygone days, a reaction such as you describe was a common and a popular means to produce an early form of glue -- now supplanted by good old Elmer's carpenter glue which is very different in composition and far superior to casein glue.


Click here to return to the Chemistry Archives

NEWTON is an electronic community for Science, Math, and Computer Science K-12 Educators, sponsored and operated by Argonne National Laboratory's Educational Programs, Andrew Skipor, Ph.D., Head of Educational Programs.

For assistance with NEWTON contact a System Operator (, or at Argonne's Educational Programs

Educational Programs
Building 360
9700 S. Cass Ave.
Argonne, Illinois
60439-4845, USA
Update: June 2012
Weclome To Newton

Argonne National Laboratory