What is Silly Putty Anyhow?

What is silly putty? Chemical & Engineering News: What's That Stuff? explains it:

"Silly putty is a dilatant compounds, which means it has an inverse thixotropy--that is, as a viscous suspension or gel, it becomes solid under the influence of pressure."

The manufacturer of silly putty, Binney & Smith, noted that it has "been the subject of dissertations by aspiring physicists and chemists."

OK, so what is silly putty? It's a mixture of silicone oil with boric acid.

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