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<p>[QUOTE=&quot;-jeffB, post: 3296519, member: 27832&quot;]Guess I&#039;d need to look harder, then.</p><p><br /></p><p><br /></p><p><br /></p><p>Why would it need to be kept frozen, I wonder? How would a perfluorocarbon <i>spoil</i>?</p><p><br /></p><p>I&#039;m looking at tetrabromoethane, density a hair under 3, which is probably cheaper. Could possibly even make it myself with pool chemicals and calcium carbide. I&#039;m not too happy about the toxicity profile, though, and I&#039;m not 100% sure I&#039;d trust a brominated compound on metals. (I know one of the formerly popular coin chems was brominated, so maybe I shouldn&#039;t worry.)</p><p><br /></p><p>There&#039;s also sodium polytungstate solution, density up to 3.10, which sounds really interesting -- but it looks like it&#039;s even more expensive.</p><p><br /></p><p>I wonder if the whole &quot;dunk it&quot; approach will die in the face of cheaper and better 3D scanning. If my iPhone 13 can take a short video of each side of a coin, then generate a dimensionally accurate 3D model of it, it would be dead easy to get a volume from that. Hmm![/QUOTE]</p><p><br /></p>

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