I.Lewis on thu 9 dec 99
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Well, I suppose more than a week has gone by since I put forward that notion
that Eutectics have nothing whatsoever do do with a glaze melting and =
maturing.
Except for one good friend who has entered into discussions with me your =
silence
has been resounding. Has no one tried out that experiment which I suggested?=
Is
there no one out there who wishes to refute my observations or rebuke me for
challenging the obvious. After all, everyone knows that salt melts ice =
because
of the eutectic. Common knowledge, plain common sense.
To remind those who read the first posting then promptly forgot or got a bit
busy and others who may have missed it, the idea is to get crushed ice and
common salt in separate containers and give them the sub zero treatment, =
either
in a cabinet freezer, or if you are in the Yukon or Alaska, on the back =
porch.
When they are well cooled, mix them up and put them back in the ultra cold =
for a
few days. Then have a look at them and report your observations.
Go on, give it a go. Nothing very scientific. Just make sure everything is =
very
cold to start with. Reporting your knowledge could provide information which
would contribute to an article on the topic of glazing.
Best regards,
Ivor. Looking for mutually exclusive ideas.
Louis H.. Katz on fri 10 dec 99
Dear Ivor,
I have not done your experiment. I know that salt will not melt very cold ice
except under the pressure of car tires and in other circumstances. Lived too lon
in Michigan to not know about this. Salt only melts ice when it is already in
solution. This is why products such as ICE MELT (Calcium Chloride) exist. They a
hydroscopic and pull water from the atmosphere, the liquid is then able to work
the ice. Whether or not the melting that takes place with ice and salt works on
same principle is not a big deal to me. Since water is vaporized way before Salt
begins to melt, well the analogy between alumina-silica and salt-water may not b
perfect.
Try this experiment.
1 part whiting
1 part kaolin
1 part silica
Fire to cone ten. It will melt to a gloss unless your whiting has too much
magnesium in it. Look up the CaO Alumina Silica Eutectic. Try adding more whitin
to your glaze, or kaolin, or silica. Any of these additions if made in any
significant quanity will result in unmelted material.
The Eutectic compositions set the point at which melts begin. Sometimes they are
just a few cones lower than the final maturation temperature of a glaze. In othe
cases such as soda-ash-containing-shino glazes they are much lower.
Salt melts ice because salt melts ice. We call the lowest melting teperature of
mixture of two materials a eutectic temperature, the composition the eutectic
composition, and point on a graph that marks this composition and temperature t
eutectic point.
The explaination rarely creates the explained.
By the way, As you consider salt, you might want to consider that the salt in
saltwater is not melted, but dissolved.
Sometimes I don't respond because I am busy, sometimes because I am lazy, other
times because I don't want to get into a battle of words on the web.
Finished the final cleanup in a firing, and have to get to bed, but first anothe
quick glance at unread email no?
Back to lurking,
Louis
"I.Lewis" wrote:
Well, I suppose more than a week has gone by since I put forward that notion
> that Eutectics have nothing whatsoever do do with a glaze melting and maturing
> Except for one good friend who has entered into discussions with me your silen
> has been resounding. Has no one tried out that experiment which I suggested? I
> there no one out there who wishes to refute my observations or rebuke me for
> challenging the obvious. After all, everyone knows that salt melts ice because
> of the eutectic.
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