Robert Santerre 6-4620, DC 0434 on wed 13 mar 96
This is a note to the group and specifically to Richard Gralnik.
Recently Richard posted a note suggesting the use of ceramic paper to line a
kiln lid. I've watched heat escaping from the imperfect seal between my
electric kiln lid and the walls of the kiln and decided to try the idea in an
effort to make my kiln a little more efficient. I bought some 1/4" ceramic
paper rated to 2400 degrees F and a refractory cement called Trowleze from a
local company specializing in refractory products and insulating furnaces.
Cementing the ceramic paper to the lid went well and everything looked fine
(the ceramic paper appeared to make a nice flexible seal) until I fired the
kiln. From about 500F to 1000F VERY noxious fumes were emitted (clearly
dangerous to breathe, taking your breath away and burning the eyes). Luckily I
have the kiln in my garage so I could just open the door and air things out.
If it had been in the house these fumes would have been a MAJOR problem.
Anyway, they dissipated and the rest of the firing went fine.
However, a more significant, long term problem has reared it's ugly head. The
refractory cement (Trowleze) shrunk during the firing, enough to actually pull
away from the soft brick of the lid (taking a thin layer of brick with it).
This shrinking has caused the ceramic paper to warp somewhat compromising the
"perfect" seal I was trying to achieve in the first place. The seal is
probably still better than the original brick-to-brick seal, but it's no
longer the "perfect" seal I wanted to achieve. And clearly the shrinking
cement has damaged the soft fire brick of the kiln lid. The shrinkage and
tearing away from the brick is most noticeable along the edges (since that's
all I can see). But some warping of the ceramic paper in the more central
parts of the lid suggest the problem exists over the entire surface of the
lid. The ceramic paper seems to still be firmly held in place so all is not
lost. It looks a little fragile, but only time and multiple firings will tell
whether or not the cement will shrink more and cause the ceramic paper liner
to separate completely from the lid (the worst that can happen is I'll have to
buy a new lid, or turn the old one over).
It seems the ceramic paper works fine. The problem was with the refractory
cement. Clearly the Trowleze cement was not meant for this application. Is
there a refractory cement that would work better (not shrink and not have so
many organics to burn out)? In retrospect, the whole thing could have worked
better if I had left about a 3" outer rim of the ceramic paper uncemented.
This would have provided enough flexibility to accomodate the shrinkage and
still give a "perfect" seal.
If anyone has a suggestion for a better refractory cement I'd appreciate it. I
may flip the lid over and give this another try. I still think it's a good
idea, but as usual the devil's in the details.
Bob
santerre_robert@lilly.com
From: SANTERRE ROBERT (MCVAX0::BOBS)
To: VMS MAIL ADDRESSEE (INT::"clayart@ukcc.uky.edu")
cc: SANTERRE ROBERT (MCVAX0::BOBS)
WardBurner@aol.com on thu 14 mar 96
Bob,
It's a shame you had problems with your ceramic paper application. Not being
familar with the specific brands you mentioned, I can't give any specific
advice. I can give some general advice when using troweling mortars and
ceramic fiber products.
First, the smell you couldn't help but notice is an organic binder used to
hold the product together during manufacturing and through he first firing.
It is present in some fiber boards and papers. It should burn out and cease
to be a problem. The second problem is a little more involved. Anytime you
cement a fiber product to brick, you are glueing the OUTSIDE of the fiber to
the OUTSIDE layer of brick. If the brick is dusty or crumbly, then you are
cementing your fiber to dust and crumbles. It won't hold. Also, many
troweling mortars have to be applied very thin 1/16" to 1/8". If the are
applied thicker, they will crack, shrink, peel, and generally screw up. The
other thing about troweling mortars that the supplier may not have informed
you about is moisture. You should wet the bricks you are attaching the fiber
to. You don't want it dripping wet, just sorta damp. This retards the the
mortar setup period and keeps the moisture from being sucked out of the
mortar, resulting in much better seal between the two products.
Marc Ward
Ward Burner Systems
PO Box 333
Dandridge, TN 37725
423.397.2914 voice
423.397.1253 fax
wardburner@aol.com
Bob wrote:
<<<<
Recently Richard posted a note suggesting the use of ceramic paper to line a
kiln lid. I've watched heat escaping from the imperfect seal between my
electric kiln lid and the walls of the kiln and decided to try the idea in an
effort to make my kiln a little more efficient. I bought some 1/4" ceramic
paper rated to 2400 degrees F and a refractory cement called Trowleze from a
local company specializing in refractory products and insulating furnaces.
Cementing the ceramic paper to the lid went well and everything looked fine
(the ceramic paper appeared to make a nice flexible seal) until I fired the
kiln. From about 500F to 1000F VERY noxious fumes were emitted (clearly
dangerous to breathe, taking your breath away and burning the eyes). Luckily
I
have the kiln in my garage so I could just open the door and air things out.
If it had been in the house these fumes would have been a MAJOR problem.
Anyway, they dissipated and the rest of the firing went fine.
However, a more significant, long term problem has reared it's ugly head.
The
refractory cement (Trowleze) shrunk during the firing, enough to actually
pull
away from the soft brick of the lid (taking a thin layer of brick with it).
This shrinking has caused the ceramic paper to warp somewhat compromising the
"perfect" seal I was trying to achieve in the first place. The seal is
probably still better than the original brick-to-brick seal, but it's no
longer the "perfect" seal I wanted to achieve. And clearly the shrinking
cement has damaged the soft fire brick of the kiln lid. The shrinkage and
tearing away from the brick is most noticeable along the edges (since that's
all I can see). But some warping of the ceramic paper in the more central
parts of the lid suggest the problem exists over the entire surface of the
lid. The ceramic paper seems to still be firmly held in place so all is not
lost. It looks a little fragile, but only time and multiple firings will
tell
whether or not the cement will shrink more and cause the ceramic paper liner
to separate completely from the lid (the worst that can happen is I'll have
to
buy a new lid, or turn the old one over).
It seems the ceramic paper works fine. The problem was with the refractory
cement. Clearly the Trowleze cement was not meant for this application. Is
there a refractory cement that would work better (not shrink and not have so
many organics to burn out)? In retrospect, the whole thing could have worked
better if I had left about a 3" outer rim of the ceramic paper uncemented.
This would have provided enough flexibility to accomodate the shrinkage and
still give a "perfect" seal.
If anyone has a suggestion for a better refractory cement I'd appreciate it.
I
may flip the lid over and give this another try. I still think it's a good
idea, but as usual the devil's in the details.
Bob
santerre_robert@lilly.com>>>>>
Richard Gralnik on thu 14 mar 96
Robert,
Ouch! I am so sorry you had problems with the glued-on ceramic paper,
and thank you for letting everyone know about it.
Were the fumes from the paper or the glue? There is something mentioned
about "organic binders" that burn out in the first firing in some insulation
products (I don't remember if the paper was one of them), and I had no
idea it smelled that bad when it burned out, if that's what the smell
was. I'll have to check with the local supplier about it.
As for glue shrinkage, I have no idea. I just hope you can correct the
situation without too much damage. Maybe it would be best to pull the
rest of the paper off the lid with a wide putty knife or something, and
just put a ring of the paper on the lid as you mentioned (that might
help avoid wear on the top bricks from leaning into the kiln to load it
too).
Please let me know how it goes.
Richard
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