[Clayart] Hydrometers - help

L TURNER magnolia.mud.list at gmail.com
Wed Jul 27 12:15:11 EDT 2016


On Mon, Jul 25, 2016 at 10:09 PM, Jeff Lawrence <jefflawr at gmail.com> wrote:


I've been testing density with a 100CC syringe .... Syringe weighs 49
grams, so if 100cc in the syringe weighs 194g,
...


Hang on a minute boys..


All the syringes I have used or seen have been designed to deliver an
amount determined by moving the plunger from "this mark" to "that mark" on
the body of the syringe; when the plunger was pushed all the way to the
zero mark, there was still some liquid in the syringe.  The point being
that a 100 cc syringe holds more than 100 cc of liquid. Yes this might only
be a cc or two on a 100 cc rated syringe, but it means that the measured
weight is for a volume greater than 100 cc, and the result is that the SG
of the glaze is actually less than the result of the gross weight of the
full syringe minus the tare weight of the empty syringe divided by 100.

I leave the error estimate to those who are good buds with Al Jay Bar.

But like Mel has said, for your personal studio the technique will give you
consistency if you always use the same syringe for each glaze.  But your
target value probably will not give the same result with a different
syringe from just anywhere.

Lou
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