Karl P. Platt on thu 16 oct 97
Far be it from me not to raise a polemic...........
I have doubts that taking an "add Mr Glassy to Ms. Fluxy and we get a
little Matty" approach to making glaze has much merit.....at all.
In fact, if anyone can't make discriminate between sodium and potassium
as being anything more than funny names represented by symbols that have
nothing to do with the way they're spelled, the notion of deriving
anything useful from calculating how many atoms are probably left behind
from a fusion of such and so materials ends up being so much mental
masturbation -- Little Matty will, therefore, be quite elusive to aquire
and we're left frustrated.
At a minimum, to undertake calculating glaze it is absolutely essential
that one knows what is represented by Avogadro's Number, what the
elements are and why they're arranged as they are on the Perodic Table
and, of course, how to add subtract, multiply and divide -- without the
aid of a PC. I'll be hard-core on this point as I was obliged to crunch
these numbers for 3 years my beater TI-57 every time new raw materials
came in.
Then there's the matter of how these substances behave when they come
together with heat -- similarities, differences and anomalies -- all of
which are well known -- and how these can be combined to deliver some
useful result. The rules by which this all occurs are not stored in the
Vatican Vault.
One would expect that *any* university student would have enough in hand
to commence a basic study of glaze technology. However, admission
standards in the US appear to have fallen well below those in the third
world -- at least from where I sit watching 15 year olds (sophmores)
children of fishermen studying calculus and chemistry on the bus every
day. No-one here is too shy about hurting someones feelings if they
can't cut it on the entry exam -- which is, I promise, a bitch. As such,
when I talk to my students here about glaze or glass technology, I do so
without reservation -- well, maybe a little, but only to clairify terms
-- everyone knows what an alkali is and what it may be expected to do in
a fusion.
No, no-one needs to know bio-chemistry to make a loaf of bread, but if
the yeast doesn't grow it's not a bad idea to have some idea as to why.
Anyway, I'll toss this out to see what comes back -- and if nothing I
might make some crack about how there are only a small handful of studio
ceramics professors competent to teach glaze making which explains the
widespread doubts and oddball concepts seen here <-- that ought to catch
some fire!
KpP -- back to zapping glaze with laser and hoping RB's book appears
soon
P.S. For the interested, find a copy of Keramische Glasuren, Rudolf
Muller, 1985. It's a very complete text of glaze technology which
features many interesting photos of effects obtained in artware glazes
-- crystals, streaks, phase separation, etc,etc,etc. All of which are
described in detail. The book's in German, but K2O remains K2O. I was
handed this book this morning and am wholly impressed with it.
Tadeusz Westawic on fri 17 oct 97
Of course you get a reply, Karl,
The bus you ride on and in which you observe the 15-year-old math
students was probably fully engineered and stress tested on a computer
long before the frame was actually laid-out in the factory. Similar
software is in use by aircraft manufacturers and architects. The more
elegant versions of the software have the capability to suggest to the
engineer what material and/or strength substitutions should be made to
correct predicted stress failures, eg. The more elegant glaze software
that I have heard of also makes "suggestions". My conjecture is that
given sufficiently sophisticated glaze calc software, one does not have
to be "the compleat chemist" to solve glaze problems and perhaps begin
to innovate.
What fine art department requires knowlege of minerology before it
permits a student to put pigment on canvas, or requires a knowlege of
metallurgy before a student can weld a sculpture? Or, perhaps the
question is "How much knowlege of minerology and metallurgy is
sufficient for the artist?"
Yeah, sure, if all one wants to teach is recalculation of a glaze for
material substitution then have at it with the calculator. If one wants
to teach original formulation, then we are currently in the province of
the Chemistry department. I think that it could and should be made
presentable at an acceptable depth to the BFA candidate in the Art
department through employment of PC's and software. Let the student
become aware of potash and soda through the software, instead of
prereq'ing it (homonic pun intended).
I know we can debate "what should be" in terms of quality of student and
quality of educator in an ideal world. But lets be a little more
pragmatic and instead start from where we are now.
Tadzu -- who once had a BA candidate ask: "How many eighths of a mile
are in a mile, anyway?" I told her there were eleven. She graduated with
her BA.
Karl P. Platt wrote:
>
> ----------------------------Original message----------------------------
> Far be it from me not to raise a polemic...........
>
> I have doubts that taking an "add Mr Glassy to Ms. Fluxy and we get a
> little Matty" approach to making glaze has much merit.....at all.
>
> In fact, if anyone can't make discriminate between sodium and potassium
> as being anything more than funny names represented by symbols that have
> nothing to do with the way they're spelled, the notion of deriving
> anything useful from calculating how many atoms are probably left behind
> from a fusion of such and so materials ends up being so much mental
> masturbation -- Little Matty will, therefore, be quite elusive to aquire
> and we're left frustrated.
>
> At a minimum, to undertake calculating glaze it is absolutely essential
> that one knows what is represented by Avogadro's Number, what the
> elements are and why they're arranged as they are on the Perodic Table
> and, of course, how to add subtract, multiply and divide -- without the
> aid of a PC. I'll be hard-core on this point as I was obliged to crunch
> these numbers for 3 years my beater TI-57 every time new raw materials
> came in.
>
> Then there's the matter of how these substances behave when they come
> together with heat -- similarities, differences and anomalies -- all of
> which are well known -- and how these can be combined to deliver some
> useful result. The rules by which this all occurs are not stored in the
> Vatican Vault.
>
> One would expect that *any* university student would have enough in hand
> to commence a basic study of glaze technology. However, admission
> standards in the US appear to have fallen well below those in the third
> world -- at least from where I sit watching 15 year olds (sophmores)
> children of fishermen studying calculus and chemistry on the bus every
> day. No-one here is too shy about hurting someones feelings if they
> can't cut it on the entry exam -- which is, I promise, a bitch. As such,
> when I talk to my students here about glaze or glass technology, I do so
> without reservation -- well, maybe a little, but only to clairify terms
> -- everyone knows what an alkali is and what it may be expected to do in
> a fusion.
>
> No, no-one needs to know bio-chemistry to make a loaf of bread, but if
> the yeast doesn't grow it's not a bad idea to have some idea as to why.
>
> Anyway, I'll toss this out to see what comes back -- and if nothing I
> might make some crack about how there are only a small handful of studio
> ceramics professors competent to teach glaze making which explains the
> widespread doubts and oddball concepts seen here <-- that ought to catch
> some fire!
>
> KpP -- back to zapping glaze with laser and hoping RB's book appears
> soon
>
> P.S. For the interested, find a copy of Keramische Glasuren, Rudolf
> Muller, 1985. It's a very complete text of glaze technology which
> features many interesting photos of effects obtained in artware glazes
> -- crystals, streaks, phase separation, etc,etc,etc. All of which are
> described in detail. The book's in German, but K2O remains K2O. I was
> handed this book this morning and am wholly impressed with it.
David Hendley on fri 17 oct 97
Yesterday Karl said:
>At a minimum, to undertake calculating glaze it is absolutely essential
>that one knows what is represented by Avogadro's Number, what the
>elements are and why they're arranged as they are on the Perodic Table
----------------------------------------------------------------------------
--------------------
Huh?
I've been formulating glazes for 25 years, doing the math pre-P.C.,
even pre-desktop calculator.
Never heard of an Avogadro.
How have I been able to manage?
Seriously, how about a quick lesson in "Avogadro's Number"?
BTW, I also think students should calculate glazes "longhand" at least a
few times
before using a glaze calculation program
Just as students should learn multiplication and division before using a
calculator.
David Hendley
Maydelle, Texas
See David Hendley's Pottery Page at
http://www.sosis.com/hendley/david/
Tom Buck on sat 18 oct 97
David H:
An Italian naturalist, Avogadro (1776-1856) discovered a key
constant of Chemistry, namely that equal volumes of all gases at standard
temperature and pressure* contain the same number of molecules. If the
volume is 22.4 litres it will contain one gram-mole, that is, the
molecular weight expressed in grams. Avogadro determined that this amount
of gaseous substance was the weight/volume of a vast number of actual
molecules, specifically 6.02 x 10 to the 23rd power (6 followed by 23
zeros) molecules. [Every so often IUPAC reports a re-evaluation of N,
Avogadro's Number (constant), and lately it is cited as 6.02252x10E23].
The significance of N is that it makes clear that a micromole
(10E-6) of a gaseous substance contains 6x10E17 molecules, a huge number,
and that a nanomole (10E-9) contains 6x10E14 molecules, and a picomole
(10E-12) still contains 6x10E11 molecules. Hence, although the amount of
gas present may be less than we can detect and analyze (most analyzers go
to 10E-9 and not much lower), there still remains in such a small volume
substantially more than half the number of molecules present in a gram
molecular weight/volume.
Now, while N is specifically correct for gases at STP*, one can
make a mental stretch and "apply" it to solutions with a known amount of
solute in a solvent. Molten glass represents a "solution" in chemical
terms, so trace amounts of a colourant, say copper I oxide (red), present
as 0.1 mole (14.2 grams) in 1000 grams of glass, would represent a vast
number of molecules of Cu2O in the liquid (aka "liquidus")... a ballpark
figure might be (repeat, might be) 10E22 molecules of Cu2O in 18x10E23
molecules of molten glass. That is, even such a small amount of red copper
oxide would be present in enough molecules to affect the moleten glass (1
molecule of Cu2O to 200 "molecules" of aluminosilcate (aka glass).
Tom Buck ) tel: 905-389-2339 & snailmail: 373 East
43rd St. Hamilton ON L8T 3E1 Canada (westend Lake Ontario, province of
Ontario, Canada).
Teri Seeley on thu 23 oct 97
Tom Buck wrote:
>
> ----------------------------Original message----------------------------
> David H:
> An Italian naturalist, Avogadro (1776-1856) discovered a key
> constant of Chemistry, namely that equal volumes of all gases at standard
> temperature and pressure* contain the same number of molecules. If the
> volume is 22.4 litres it will contain one gram-mole, that is, the
> molecular weight expressed in grams. Avogadro determined that this amount
> of gaseous substance was the weight/volume of a vast number of actual
> molecules, specifically 6.02 x 10 to the 23rd power (6 followed by 23
> zeros) molecules. [Every so often IUPAC reports a re-evaluation of N,
> Avogadro's Number (constant), and lately it is cited as 6.02252x10E23].
> The significance of N is that it makes clear that a micromole
> (10E-6) of a gaseous substance contains 6x10E17 molecules, a huge number,
> and that a nanomole (10E-9) contains 6x10E14 molecules, and a picomole
> (10E-12) still contains 6x10E11 molecules. Hence, although the amount of
> gas present may be less than we can detect and analyze (most analyzers go
> to 10E-9 and not much lower), there still remains in such a small volume
> substantially more than half the number of molecules present in a gram
> molecular weight/volume.
> Now, while N is specifically correct for gases at STP*, one can
> make a mental stretch and "apply" it to solutions with a known amount of
> solute in a solvent. Molten glass represents a "solution" in chemical
> terms, so trace amounts of a colourant, say copper I oxide (red), present
> as 0.1 mole (14.2 grams) in 1000 grams of glass, would represent a vast
> number of molecules of Cu2O in the liquid (aka "liquidus")... a ballpark
> figure might be (repeat, might be) 10E22 molecules of Cu2O in 18x10E23
> molecules of molten glass. That is, even such a small amount of red copper
> oxide would be present in enough molecules to affect the moleten glass (1
> molecule of Cu2O to 200 "molecules" of aluminosilcate (aka glass).
>
Another way to say this is that the "gram molecular weights" of
different
substances all contain the same number of molecules (the constant called
Avogadro's Number). Thus we can test the results of combining different
ratios of glaze molecules by carefully weighing glaze ingredients
expressed
as ratios of their gram molecular weights.
Most glaze calculation software packages have the gram molecular weights
for the common glaze ingredients built-in. They also have built-in
logic
for converting glaze recipes (ratios of raw materials) to glaze formulae
(ratios of molecules). The latter enable us to think of glazes in
terms of their molecular proportions, a more powerful mental model than
expressing them simply as the ratio of their raw ingredients.
Bill
--
Theresa and William Seeley 410 486-3171 (voice)
Villa Nova Pottery 410 484-6273 (fax)
4015 Buckingham Rd. Baltimore, MD 21207
"186,000 miles/second is not just a good idea - it's the law!"
| |
|
