eutectic ...help!

updated thu 26 nov 09

Jess McKenzie on sat 21 nov 09

This discussion about "eutectic" is almost as
confusing as my grad course in physical chemistry.
Then, I found it a very complex subject--not so
complex when only *two* components are considered,
but with three components it gets trickier and with
more than three...

I finally caught on. Now, I'm confused again. I
can't imagine a glaze that does *not* qualify as a
eutectic mixture, so you must be talking about
another kind of eutectic. Can someone help me
understand this new paradigm?

thanks...~jess

Lee Love on sun 22 nov 09

On Sat, Nov 21, 2009 at 6:46 PM, Jess McKenzie wrote=
=3D
:

> I finally caught on. =3DA0Now, I'm confused again. I
> can't imagine a glaze that does *not* qualify as a
> eutectic mixture, so you must be talking about
> another kind of eutectic. =3DA0Can someone help me
> understand this new paradigm?

Jess, how about a glaze that is only made of one material? Like Albany Sl=
=3D
ip?


--=3D20
--
Lee, a Mashiko potter in Minneapolis
http://mashikopots.blogspot.com/

"Ta tIr na n-=3DF3g ar chul an tI=3D97tIr dlainn trina ch=3DE9ile"=3D97tha=
t is, "T=3D
he
land of eternal youth is behind the house, a beautiful land fluent
within itself." -- John O'Donohue

Steve Slatin on sun 22 nov 09

It's not a new paradigm, Jess, it's=3D20
an old distinction of definitions.

Some people on the list insist that
the word "eutectic" be restricted to
the specific mixing of elements that
creates the single lowest possible
melting point for those elements.

Others use it more generally to mean
the interaction of materials that=3D20
permits a lower melting point than
any of the individual materials would
melt at.

For some reason when I learned the
term there was a distinction between
an "eutectic point" (the first definition)
and an "eutectic" (the second definition.

I can't remember, though, even what field=3D20
this distinction was used in.


Steve Slatin --=3D20




--- On Sat, 11/21/09, Jess McKenzie wrote:


> This discussion about "eutectic" is
> almost as
> confusing as my grad course in physical chemistry.
> Then, I found it a very complex subject--not so
> complex when only *two* components are considered,
> but with three components it gets trickier and with
> more than three...
>=3D20
> I finally caught on.=3DA0 Now, I'm confused again. I
> can't imagine a glaze that does *not* qualify as a
> eutectic mixture, so you must be talking about
> another kind of eutectic.=3DA0 Can someone help me
> understand this new paradigm?
>=3D20
> thanks...~jess
> =3D0A=3D0A=3D0A

Jess McKenzie on sun 22 nov 09

Gee, Steve, an old distinction? How old? Guthrie
coined the term "eutectic point" in 1884.
(True, but kidding anyway.)

So far as I know, there's only one term, "eutectic
point," meaning the concentration of each of n
components to yield the lowest melting point.

Note the word "point," which should give you one
reason for my query. Listers were using the word
"eutectic," so I wondered if there weren't another
meaning, held perhaps only by enlightened members of
the list.

So, I asked for help, noting that I could not
envision a glaze containing a single component, or
words to that effect. The very first response was a
claim that Albany Slip is a *single* component. That
floored me, for I knew that Albany contains at least
nine oxides! Through the Looking Glass indeed!
Eventually, Lou Turner--bless him--shows up to
demonstrate that at least two of us speak the same
language. (Lou also offered a few valuable
references).

And now, you show up to explain it all. Bless you
too. I'm a bit more comfortable with it all now,
despite suspecting that C. P. Snow may have known
what he was talking about. For those on the list who
do not know what *I'm* talking about, I recommend a
fast read of "Zen and the Art of Motorcycle
Maintenance."

Thanks, Steve...~jess

Date sent: Sun, 22 Nov 2009 15:57:00 -0800
(PST)
From: Steve Slatin

Subject: Re: Eutectic ...help!
To: Clayart@LSV.CERAMICS.ORG,
jo01_je02@OLYPEN.COM

It's not a new paradigm, Jess, it's
an old distinction of definitions.

Some people on the list insist that
the word "eutectic" be restricted to
the specific mixing of elements that
creates the single lowest possible
melting point for those elements.

Others use it more generally to mean
the interaction of materials that
permits a lower melting point than
any of the individual materials would
melt at.

For some reason when I learned the
term there was a distinction between
an "eutectic point" (the first definition)
and an "eutectic" (the second definition.

I can't remember, though, even what field
this distinction was used in.


Steve Slatin --




--- On Sat, 11/21/09, Jess McKenzie
wrote:


> This discussion about "eutectic" is
> almost as
> confusing as my grad course in physical chemistry.
> Then, I found it a very complex subject--not so
> complex when only *two* components are considered,
> but with three components it gets trickier and with
> more than three...
>
> I finally caught on.=3DA0 Now, I'm confused again. I
> can't imagine a glaze that does *not* qualify as a
> eutectic mixture, so you must be talking about
> another kind of eutectic.=3DA0 Can someone help me
> understand this new paradigm?
>
> thanks...~jess
>

Craig Martell on sun 22 nov 09

>Jess, how about a glaze that is only made of one material? Like Albany S=
lip?

A glaze containing only Albany is indeed a "one material" glaze but Albany
slip contains four fluxing oxides plus alumina and silica. This would
qualify as a possibility for eutectics within the single substance. But,
I'm not saying that this is the case, just possible because of the complex
blend within Albany.

regards, Craig Martell Hopewell, Oregon

Jess McKenzie on sun 22 nov 09

The nine oxides in Albany notwithstanding, Gents, as
soon as you apply it to another clay body you've got
9+n compounds to deal with. And we speak of eutectic
point, we really are talking about compounds, not
materials.
~jess


Date sent: Mon, 23 Nov 2009 08:57:42 +1100
Send reply to: Des & Jan Howard

From: Des & Jan Howard

Subject: Re: Eutectic ...help!
To: Clayart@LSV.CERAMICS.ORG

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Lee
Agreed the glaze is made of one material, but I doubt
if even Albany Slip is made of one component. An XRD
analysis would be necessary. One of the main glazing
materials we use is a "yellow ochre" from a nearby
old
ironstone mine. This makes a matt metallic glaze at
stoneware.

Another material I use is a local clay-like material
dug from a limestone mine. Dry scraps are harder than
most biscuit, when fired to biscuit it's dense &
darkish bright orange & is a temmoku glaze at
stoneware.
Des

Lee Love wrote:
> Jess, how about a glaze that is only made of one
material? Like Albany Slip?

--
Des & Jan Howard
Lue Pottery
Lue NSW
Australia
2850

02 6373 6419
www.luepottery.hwy.com.au
-32.656072 149.840624

ivor & olive lewis on mon 23 nov 09

Dear Jess McKenzie,

You have the skills to do the research. Why not have a read at the
references I have given.

You tell me <mixture, so you must be talking about another kind of eutectic. Can someon=
e
help me understand this new paradigm?>>

In early research it was seen there was a need to discriminate two well
known effects or phenomena which were blessed with the term "Eutectic". One
is where the components which comprise the Eutectic system, at constant
pressure and constant temperature were in equilibrium with the liquid they
became on fusion. Change the temperature, change the pressure and you chang=
e
the material state and one of the phases disappears.

Enter Herr Seger with his Pyrometric Cones which are made to bend. The
utility of his device is that they do not melt and become a puddle, do not
change phase catastrophically as they indicate all that heat work has been
done. They partially melt and bend.

Someone, in the late 19th or early 20th Cent had the sense to clarify the
distinction to prevent confusion and termed this phenomenon "A Deformation
Eutectic". Singer and Singer make this distinction clear.

Regards,

Ivor Lewis,
Redhill,
South Australia