Does anyone have experience of using ceramic blanket in kilns for
either enamelling or for burnout> I would appreciate hearing your
comments.
Richard
ROn ichard Whitehouse’s question on using ceramic blanket in kilns
for either enamelling, I have used Thompson Enamels’ kiln blanket for
about 6 years. It is especially useful when I am teaching and usuing
my own kilns. The students almost always spill enamels on the kiln
floor and the blanket protects the floor and is then discarded.
Donna in WY
Here are more basic sources :
http://www.paragonweb.com/
http://www.thermalceramics.net/
http://www.unifrax.com/web/pages.nsf
Paragon makes furnaces , especially very nice fiber insulated small
kilns for Precious Metal Clay, enameling etc. These have state of art
solid state programmable controllers . They are very reasonable in
price. UK??? The other two are primary manufacturers of the fiber
insulation. Jesse
I have used a lot of InsWood and KaoWool ceramic blanket for ceramic
kilns for many years. Very effective insulator. However, in an area
as small as a jewelry kiln, you would need to be very careful hot to
brush against the wool which may loosen fibers. I would recommend
using the harder fiber based panels. Just as good for insulating
purposes, but I believe will suite the purpose better and last longer,
taking more use/abuse. Also, try to touch the project before you buy.
I react to one product like fiberglass fibers (light rash and
itching), but not the other. Many potters I know have the same
"problem" and there’s no consistency. I use gloves when I handle the one
I react to and have no problems.
I have used ceramic blanket on a little larger scale - 50 pound pours
of bronze into ceramic shell molds. For this we use a very simple kiln
( Raku Kiln) made of expanded metal or concrete reinforcing wire mesh
( about 6"X6" grid) Its great for this. And could be used for a
smaller burnout kiln… The material is very friable and can does
break down into particles that would make a simple kiln for enameling
impractical. A rigid board form of the same fiber material is used in
some small furnaces suitable for enameling. I don’t know what is
available in the UK. Some things are available here and not there and
vise versa. My bookmarks are disorganized here is one on the rigid
material used with heaters:
http://www.thermcraftinc.com/heaters.html Search in kilns and in
ceramics. I’ll dig out a few more sites. I think you have a simple
cheap material available in the UK Its a gypsum building block about
brick size (4-1/2"x9’ x 2 -1/2" or so) . Its used for interior
walls. It used to be available in the US but I have not seen or heard
of it in years here. Its not as good as the Ceramic fiber systems but
it costs less. Jesse
Was I talking about the same thing as the Thompson blanket? the
stuff I was talking about is called Kaowool or Fibrefrax. The normal
blanket is about 1" thick something like ceramic cotton wool or
fiberglass but it is fragile and breaks into dusty pieces. Not good
for lungs and it would get into enamel work. Jesse
Does anyone have experience of using ceramic blanket in kilns for either enamelling or for burnout> I would appreciate hearing your comments.
Rich - At an Art show I did last summer a pottery demonstration used
a ceramic blanket wrapped with hardware cloth (coarse wire screening
- c. 1/2 in. sq. openings) to form a cylinder about 1.5 ft diameter,
sat it on some fire bricks and closed the other end with another
piece of blanket. They inserted a propane-fired flame head at the
bottom of this contraption and were using it to fire their glazes !!
They’d pull the red-hot pieces out of their makeshift kiln, drop them
into a box of straw, leaves, sawdust, and what-not, and vio-la -
instant raku to go. Nifty! So experiment away - it can be done!
Mike
I have a very large kiln built out of 1 inch Fiberfrax blanket on the
inside, reinforced by 3 inch thick Fiberfrax block on the outside. I
also have a large soft firebrick kiln. There are differences in the
insulating qualities of these materials which you might consider when
deciding on the materials for your kiln.
Firebrick kilns take a relatively long time to heat up because you
must bring the volume of the brick up to your temperature. But the
material itself holds heat and continues to radiate it, even with the
element turned off. By contrast, ceramic fiber blanket does not itself
get hot, but acts as a “heat mirror”. (I’m told it was developed by
NASA to protect satellites from burning up upon reentry in to the
atmosphere.) Your kiln will initially heat up much more rapidly, but
will also lose its heat fairly quickly once the element is off,
especially if the door is momentarily opened.
Some comments about the durability of each material: someone else
suggested coating the blanket in the rigidizer solution to harden it.
Personally, I would not recommend doing this. The rigidizer breaks
down over time with heat, and becomes crumbly. I haven’t experienced
any significant deterioration of my (uncoated) ceramic fiber kiln.
However, it is constructed in a rather unique way, such that the
elements add support to the blanket. I’m also pretty careful with it.
There is another issue to consider with the blanket, however, in it’s
use in an enameling kiln. The stuff is virtually soluble in molten
glass. This means if enamel drips on the blanket, you will have a
hole which is difficult to repair. Brick is damaged by molten glass as
well, but not to the same extent, and can be repaired with firebrick
repair paste. The blanket does seem to be somewhat more fragile,
overall.
As far as fiber “dust” contaminating the glass, my large ceramic
fiber kiln is strictly a glass casting and fusing kiln, has blanket on
the inside of the lid, and I have never experienced any dust from the
fiber. It doesn’t seem to shed fibers. (The exterior hard block is
very dusty however, and I coated it with rigidizer.) However, I don’t
fire at enameling temperatures very often, nor am I opening and
closing the kiln as often as an enamelist does. At higher enameling
temperatures the blanket would tend to break down, and this could be a
problem in an enameling kiln. At some point you would probably need
to reline the interior of your kiln. This deterioration, combined with
the way the glass eats into the blanket when molten, would steer me
away from its use in an enameling kiln. I think as a burnout kiln,
where it is being used at consistently lower temperatures, it would
hold up just fine.
There are pros and cons to its use. Hope this helps a little.
Rene Roberts
I have been using kilns made like this for 8 (yup read 8, it is
correct) years one to burn out ceramic shells and one to melt 85 lb
crucibles fo bronze. Have had to rebuild the lids a couple of times,
but who cares. Ues a 2" pipe, squirrel fan and a 1/2"pipe nozzel with
25 psi propane and can melt 85 lbs of bronze (2100F) in a bit over an
hour. Go for it. John Dach
Does anyone have experience of using ceramic blanket in kilns for
either enamelling or for burnout. I would appreciate hearing your
comments.
Richard, If you wish to save the bottom of the kiln from
contamination, our enamelists in the guild here use a piece of kiln
shelf cut to fit the bottom of our kilns and cover it with kiln wash,
which you buy in powdered form at any ceramics shop. We mix it with
water and brush it on very thickly; it dries quickly. When you have
spills, you can scrape it off after the shelf cools and the enamel
comes right off with it.You then coat the shelf again before using. We
find this the easeist way of dealing with spills. Louise Gillingham in
San Diego @lgillin1
I use ceramic fibre blanket as a lining for my metal melting furnace
, a 1" thickness works ok for melting 1kg of metal . I am just about
to make a larger one for up to 3kg . You need to use soft firebrick to
rest the crucible on , if you spill molten metal on the fibre it will
eat it’s way into it. I got it from Bath Pottery Supplies so I suppose
any pottery supply place would do it. i have just bought a second hand
top loading pottery kiln which makes a great burnout kiln for large
flasks and use a cambridge kiln programmer also bought through bps
(�275+vat much cheaper than jewellery suppliers). there are far more
potters than jewellers around so the prices of equipment for them is
much more competitive. Tim.
The furnace floor blanket often recommended for enameling furnaces is
really a Fiberfrax or Kaowool paper (Thompson’s PH-4 product is
Fiberfrax 970 paper). The purpose of using these blankets on the
floor of a furnace is that it is cheaper then a kiln shelf for
protecting the furnace floor from falling enamel powder and that it is
thinner than a shelf therefore giving the kiln dimension more height
if needed. The drawbacks aRe: the paper stinks like crazy when the
adhesives are burning out; it deteriorates rapidly and can snag
trivets or racks when it gets too worn; because it is an insulating
substance, it blocks some of the heat from the furnace floor.
Judy
Louise, do you mean a thin piece of firebrick for kiln shelf or
something else and where do you get a piece of “kiln shelf” Thanks
Miki