WardBurner on tue 10 mar 98
Hey folks,
I haven't been posting much lately, just lurking about....Started to hit the
"reply" button on several issues, but thought "no don't get dragged into this
one". That's one of the problems with this form of communication. You post
some practical info, then BAM!, you have to justify, repost, explain, conjole,
back and forth. It's great fun and a learning opportunity for some, but can be
a real time drain for others. Plus, who the hell are you supposed to believe?
There is so much misinformation floating around it's best to avert your eyes
less you spend all day typing posts. Witness the "crackle on Raku" thread
going on right now. So here are my thoughts on these two subjects. Let's
underline the word "thoughts". I don't have any hard numbers on the two
topics, just a few years of practical experience. If you have "hard numbers"
let's see them. If I'm wrong, I really need to know 'cause I make my living
helping folks. Here goes....
Fiber Compression
If you compress fiber it will lose some of it's insulating value. I think some
of the disagreement between Jonathon and I believe Marshall (hope I have the
two correct people) was because they were coming from different directions.
One said, and I paraphrase, "if you compress fiber it will lose some of it's R
value". This is true, but R value is not an appropriate designation. Then
Jonathon said something like. "they make compressed fiber products that have
great insulating values, compressing the stuff doesn't make it lose any of
it's insulating value" Guess what? This is true also. One inch of fiber
blanket has great insulating properties. So does one inch of fiber board. But,
if you compress the fiber down to 1/4 inch, it will not have the same
insulating value as 1 inch of fiber. Now take 4 inches of fiber, compress it
down to 1 inch, and you have board and a great insulator. The thickness of
the fiber product is more the determining factor that the density of the
material. Both have very low heat storage to mass relationships. So, I feel,
both were right. We just needed a little clarification on an "apples &
oranges" type of disagreement.
ITC
Right up front I want ya'll to know two things; I don't know what's in ITC
(though I have my suspicions) and I sell the stuff. Alice & Feriz won't say
what's in their products and I don't blame them. If it was mine, I wouldn't
tell either.
ITC is not magic! A good product, but not supernatural. I believe it works by
lessening refractory surface area and permeability. New kilns (electric or
gas) are pretty tight and smooth on the inside. I don't think spraying ITC on
new kilns will make much difference and could actually prove less efficient in
a brand new electric kiln. New kilns are tight (no tertiary air) and smooth
(less surface area). As a kiln ages, surface anomalies arise (sounds cool
huh?) as does cracks and air pathways. Both of these decrease kiln efficiency.
Surface area increases due the roughness or uneveness of surfaces, causes some
turbulence in the case of gas kilns which may drop efficiency. This is not
near as much of a problem as the porosity of the kiln. Heat transfer out by
convection and cool air transfer into the refractories will drop efficiency
and lengthen firing times. What, I believe ITC does, is produce a smooth tight
surface with a realitively low thermal mass. I believe, if you sprayed the ITC
coating on so that it was 4 and 1/2 inches thick, it would have the insulating
properties of a zirconium brick. Those properties are horrible. Well, this was
my 2 cents worth. If you want to send me long detailed posts, I'll read them.
But, I probably will send you back a form letter asking you to call. Don't
mean to be rude, but I have a lot on my plate with NCECA coming up and I ain't
the world's fastest typist. See Ya'll in Ft Worth
Marc Ward
Ward Burner Systems
PO Box 333
Dandridge, TN 37725
USA
423.397.2914 voice
423.397.1253 fax
wardburner@aol.com
Talbott on wed 11 mar 98
There are refractory coating materials which Marc Ward described that will
reduce heat loss primarily by sealing up cracks that are a lot less
expensive than $140 per gallon. I would suggest that one could contact
A.P. Green and perhaps even Skutt Kiln Co. for information on these
products...
As you know heat is conducted by three ways: conduction, convection, and
radiation. Consider that.
Good point! There is no magic when it comes to insulators just laws of
physics... ...Marshall
>----------------------------Original message----------------------------
>Hey folks,
>
>I haven't been posting much lately, just lurking about....Started to hit the
>"reply" button on several issues, but thought "no don't get dragged into this
>one". That's one of the problems with this form of communication. You post
>some practical info, then BAM!, you have to justify, repost, explain, conjole,
>back and forth. It's great fun and a learning opportunity for some, but can be
>a real time drain for others. Plus, who the hell are you supposed to believe?
>There is so much misinformation floating around it's best to avert your eyes
>less you spend all day typing posts. Witness the "crackle on Raku" thread
>going on right now. So here are my thoughts on these two subjects. Let's
>underline the word "thoughts". I don't have any hard numbers on the two
>topics, just a few years of practical experience. If you have "hard numbers"
>let's see them. If I'm wrong, I really need to know 'cause I make my living
>helping folks. Here goes....
>
>Fiber Compression
>
>If you compress fiber it will lose some of it's insulating value. I think some
>of the disagreement between Jonathon and I believe Marshall (hope I have the
>two correct people) was because they were coming from different directions.
>One said, and I paraphrase, "if you compress fiber it will lose some of it's R
>value". This is true, but R value is not an appropriate designation. Then
>Jonathon said something like. "they make compressed fiber products that have
>great insulating values, compressing the stuff doesn't make it lose any of
>it's insulating value" Guess what? This is true also. One inch of fiber
>blanket has great insulating properties. So does one inch of fiber board. But,
>if you compress the fiber down to 1/4 inch, it will not have the same
>insulating value as 1 inch of fiber. Now take 4 inches of fiber, compress it
>down to 1 inch, and you have board and a great insulator. The thickness of
>the fiber product is more the determining factor that the density of the
>material. Both have very low heat storage to mass relationships. So, I feel,
>both were right. We just needed a little clarification on an "apples &
>oranges" type of disagreement.
>
>ITC
>
>Right up front I want ya'll to know two things; I don't know what's in ITC
>(though I have my suspicions) and I sell the stuff. Alice & Feriz won't say
>what's in their products and I don't blame them. If it was mine, I wouldn't
>tell either.
>
>ITC is not magic! A good product, but not supernatural. I believe it works by
>lessening refractory surface area and permeability. New kilns (electric or
>gas) are pretty tight and smooth on the inside. I don't think spraying ITC on
>new kilns will make much difference and could actually prove less efficient in
>a brand new electric kiln. New kilns are tight (no tertiary air) and smooth
>(less surface area). As a kiln ages, surface anomalies arise (sounds cool
>huh?) as does cracks and air pathways. Both of these decrease kiln efficiency.
>Surface area increases due the roughness or uneveness of surfaces, causes some
>turbulence in the case of gas kilns which may drop efficiency. This is not
>near as much of a problem as the porosity of the kiln. Heat transfer out by
>convection and cool air transfer into the refractories will drop efficiency
>and lengthen firing times. What, I believe ITC does, is produce a smooth tight
>surface with a realitively low thermal mass. I believe, if you sprayed the ITC
>coating on so that it was 4 and 1/2 inches thick, it would have the insulating
>properties of a zirconium brick. Those properties are horrible. Well, this was
>my 2 cents worth. If you want to send me long detailed posts, I'll read them.
>But, I probably will send you back a form letter asking you to call. Don't
>mean to be rude, but I have a lot on my plate with NCECA coming up and I ain't
>the world's fastest typist. See Ya'll in Ft Worth
>
>Marc Ward
>Ward Burner Systems
>PO Box 333
>Dandridge, TN 37725
>USA
>423.397.2914 voice
>423.397.1253 fax
>wardburner@aol.com
http://www.PotteryInfo.com
101 CLAYART MUGS (Summer 1998)
2ND ANNUAL CLAYARTERS' GALLERY - NAPLES, MAINE (Summer 1998)
E-MAIL ME FOR APPLICATIONS
http://fmc.utm.edu/~dmcbeth/cag/naples.htm
Celia & Marshall Talbott, Pottery By Celia, Route 114, P O Box 4116,
Naples, Maine 04055-4116,(207)693-6100 voice and fax,(call first)
Clayarters' Live Chat Room, Fri & Sat Nites at 10 PM EDT & Sun at 1 PM EDT
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