KarateHiro on fri 13 mar 98
As promised, this is a sequel to the original entitled "ITC and Common Sense
(Basics)", that I posted yesterday. It surprised me to see so many post
exchanged on ITC in the last 24 hours since I sent in mine. They have nothing
to do with mine, needless to say. I feel they have reinforced the points I
wished to make in subsequent posts of mine on this subject that I plan to
follow up. Useful and helpful -- all of them, actually. This post expands on
the previous basics, and should be followed by a potter's common sense at
intermediate level. Nothing fancy, so no specific references, scientific
credits or personal tribulations. Just my observations.
First off, I have noted that there are some respected potters who wish to keep
a personal glaze recipe a true secret, if not true lies. Despite the fact that
they often offer workshops, demonstrations or lessons, they have managed to
keep the glaze recipes a secret. I think this has given them a competitive
edge with an aura of mystery, help them sell the pots wherever they can, and
get invited to more public exposure. It is one of the keys to their success,
and has something to do with what has brought them to where they are today.
Naturally, they wish to keep things that way. The more mysterious, the better.
I have also noted that some of these potters have had no reservations about
endorsing the benefits of ITC. They have been quite willing to share its
wonders, with which they have personally been associated (consequently
benefited, giving them a bit of another competitive advantage). I for one
would be reluctant to confer competitive advantages to others
indiscriminately, if my personal philosophy tells me to keep the persosnal
glaze recipes a secret. But not so in this case. Quite the opposite, a
generous gesture all around. So I thank those who have given us this
technological, industrial marvel by bringing it out in the open.
Seriously, a catch here is that the composition or properties of the material
are a closely guarded secret, just like the personal glaze recipe. So, we
should thank those who have given us this industrial product, why not take
advantage of it, the benefits are proven, etc., etc., the average potter who
does not subscribe to its virtues are considered renegate, not fit to be
deemed a true potter. Coming from those who produce those pots, such remarks
are credible. After all, their glazes are wonderful. Why not their kilns! Or,
anything else they say. Right?
Another catch could be that the materials kept secret may be like the personal
glaze. It consists of ordinary, common materials, with a bit of snake powder,
if not the snake oil, thrown in. What makes it so special is the personally
secret recipe. Once the details are revealed, anyone could reproduce
(replicate in scientific terms) the darn stuff. And neeedless to say, the darn
stuff should work just fine, or satisfy the user to the n'th degree. If this
happens, it should dispell any doubts about its usefulness or about the
ascribed benefits, virtues, and, yes, scientific validity.
Too long a preamble. Too much mumbling. Sorry. Please forgive me. I have no
time to edit this one down.
My common sense tells me that the original ITC or its derivatives were made to
protect the spacecraft that comes into contact with the oxygen upon re-entry
in upper stratosphere at high speed. Well, it is natural to reason that we
now use it to protect kiln skins (interior walls, ceilings, floor, etc). But,
hard bricks and compressed fibers are thick skinned. They are designed to take
pressure or compression if you prefer more precise terms. They do not crumble
that easy even under extreme pressure. You can step on them, and they do not
budge. I think there are human beings like that, easy to find among political
species. You got the picture? The ITC may help, but not much. They are energy
guzzlers, to begin with.
That brings us to the soft stuff. There are degrees of hardness and softness.
Soft bricks and soft ceramic fibers come in varying degree of pliability,
insulating values, and high temperature tolerances. In general, the softer the
material, more insulating value. The softer, the more vulnerable to external
pressures. Like human beings, for sure. The hotter ones could easily burst
open at seams.
This generalization does not always hold, since the material used could be
tougher and harder (and heavier), while lots of air could be trapped to help
its insulating value. The more air, no matter the material used, could cause
weakness against external pressures, including abrasion, shocks and so on. Did
you know the size of bubbles in home made bricks make a big difference here?
Lots of details like that are available on the subject. Potters have done
research and reported on them. Honest to the microns. Sorry, I do not have the
exact references ready at hand. Cannot help you. But I am sure others can.
The reason why the softer materials have more insulating value largely derive
from the amount of air entrained. In the earthy domains we inhabit. I am
talking about the common materials used to make potter's kilns. Not the
exterior skin of the spacecraft. Remember we have been discussing the
insulating quality of the materials protected by the space age stuff. The
common materials cannot be elevated to the cutting age space level by the
whiff of the space age material.
Air is lighter than most anything we know of around the kiln. Ironically, the
softer the fiber, the higher the firing temperature, more fluffy it looks and
feel. This is what I observed, and not the scientific truth, mind you. I
frankly do not know how ITC can protect such a stuff, unless it by itself
makes a strong, thick skin of its own to take the pressure. Otherwise, things
could crumble. Space age ceramic materials do exist. Ceramic auto engines do
exist. The material is as tough as it gets and could take tremendous pressure
at an extremely high temperature. But even at slight provocation (at the wrong
place with just a tap) it could shatter into pieces. Especially when it is
cold at lower temperatures. It's one of the main reasons why it is not widely
used. Cost is another major factor. Sounds like ITC, does it not?
I do not know how this observation relates to the cutting edge material used
by potters. Must trust intuition and common sense. So far, I have talked about
the properties of the material to be protected by the cutting-edge material.
Hard stuff first, and then the soft stuff. And how the insulating values are
derived.
Next let us talk about the insulating properties. Not much air is up there
where the original ITC protected the spacecraft including the outer skins of
the spacecraft. In contrast, the air abounds in and out of the potter's kiln.
What is protected contains the air. That makes things complicated. Especially
when we talk about the insulating bit.
..* * * * * .. ... ... ...
Another sequel should follow soon in a day or two. It's another promise I
shall keep. I have a fabric and textile show to attend tomorrow morning, but
should be able to manage another post. It should have the title: ITC and
Common Sense (Insulated).
Hiro Matsusaki
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