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hydrometers and other things

updated tue 30 apr 96 on mon 15 apr 96

The Clay Studio in Philadelphia is a wonderful, interesting, and unusual
place. Go to the gallery, take a class, whatever, it's good.

Part of the hydrometer discussion might need to include the fact that slips,
especially deflocculated slips, aren't really liquids in the everyday sense
of the word. Weight per uint volume compared to water is the definition of
specific gravity. The thixothropic properties of high density slips probably
prevent accurate hydrometer readings. The shear resistance of the material
prevents the hydrometer from sinking far enough to displace as much fluid as
it might under other circumstances. Perhaps this problem could be addressed
by vibrating the slip, the way they do concrete, while making a reading.

In the drilling world, where large quantities of bentonite are mixed with
water for drilling fluid, some characteristics of the mix are determined by
timing the emptying of a standard funnel. The funnel is filled with fluid
while a finger covers the outlet and then the timer is started when the
finger is removed. When no more comes from the spout, the timer is stopped.
I believe one of the mud suppliers sold or supplied this "standard" funnel.
Of course, any funnel could be a standard if you can keep track of it.

Joe Herbert