Talk:Dilatant

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Someone removed Custard as an example. Custard is most definitely dilatant, though it depends on the thickness to which it is mixed - custard that has set or else is very thin and runny isn't noticably dilatant. It has to be "just right". How do I know this - well, partly common experience. But also, there was a memorable demonstration on UK TV once, for a show about science (forget its name, but it was the one with Magnus Pyke). They filled an entire bathtub with custard, They got a few volunteers to roll up their trousers and walk through it. Of course, you could walk (or wade) through the custard. Then they got them to RUN through it. The custard supported their weight and so instead they ran across the top of it. The effect was quite remarkable! The reason was the dilatant property - the force of a running foot striking the surface caused the dilatant liquid to thicken locally and become more viscous, supporting the weight. Finally, consider that custard is mostly corn starch and water, with egg and vanilla flavouring added, and as corn startch is already mentioned, its dilatant properties should not be all that surprising.

[edit] Silly putty

Silly putty page says silly putty is not strictly dilatent: perhaps a different example should be used

The problem with giving "good" examples is that most non-Newtonian fluids don't fall neatly into a single category, nor are the categories mutually exclusive. Dilatant means that a fluid thickens under shear, and Silly Putty most definately does exhibit that property--yank it, it snaps, hit it with a hammer, it shatters. Silly putty is also visco-elastic, in that in its thickened state, it rebounds after deformation, which is why after it snaps it rebounds, and when thrown at the floor, it bounces. I have been meaning to re-do the chart at the non-Newtonian fluid article (see Talk:Non-Newtonian_fluid) to make this more clear, as other people have expressed confusion over different example substances also appearing in other categories. scot 14:33, 24 Jun 2005 (UTC)

It seems to me that if silly putty is not a dilatant, we should not give it as an example as one even if it demostrates some of the properties of one. However if you do wish to include it, I think you need to at least mention it is not a dilatant even if it shows similar properties Nil Einne 15:14, 11 November 2006 (UTC)

[edit] Possible vandalism alert

Slashdot recently linked to an article that prominently linked to this page on Wikipedia so keep your eye out for vandals. --froth^{T C} 07:42, 4 January 2007 (UTC)