[Clayart] Flame movers
Lee via Clayart
clayart at lists.clayartworld.com
Sat Feb 21 15:29:56 EST 2015
I have the bigger version. It fires so easy, I only have one cone 10 cone
at the middle peep. The bottom finished cone 11 and the top a soft 10.
I have a pyrometer at the top and bottom peeps and is the best tool for
knowing if you are getting reduction (along with a flame coming out of the
Four things really help:
1. use props to make a baffle shelf about an inch and a half from the
exit flue, inside the kiln.
2. Split the shelves and have as big a gap between the two halves in the
middle, to make the pressure come to the center from the sides. I even
have a set of oversized 26" shelves that really help cut off the space on
3. Make sure the primary air is closed down to 1/4"
4. put "flame spreaders" at two diagonal ports inside the kiln (described
When you have proper reduction, the bottom will get ahead of the top. My
finish has the bottom a little ahead of the top. My damper is never over
half open and maybe an inch past half open during reduction.
Read this article and do exactly as he says:
Torchbearer Firing Tips
I fire to cone 9-10 and (the temperatures) are almost identical top /bottom
with only a few degrees difference through most of the firings. I fire
smaller/larger wheel thrown, slab built rectangle and combo-built ovals up
to about 22" max.
One comment first. You need a dual pyrometer setup. I got a fluke and use
the 12" probes with the ceramic protection sleeves. These fit snug in the
peep holes and keep the probes from sagging. I don't think it's a fire-able
kiln with any success without the dual pyro setup.
I use one probe in top peep and one in bottom. I set a 7,8,9,10 self
supporting cone set on a strip of clay just at the end of the probe inside
about 9-10". At that distance you can see them good later. I use TWO flames
spreaders on two of the four ports. I use a two inch post on each side of
the port with a 5" post laying across them and up against the wall. This
gives a tiny space against wall but directs most flame out. The other two
ports are not tampered with. Bottom shelf is a tad more than 4" above floor
( 1/2" above spreader arrangement 2" post with side-turned post which gives
1 1/2" more height = 3 1/2"). I use two cone six half shelves on floor with
3 1/2" posts supporting the first shelf. Shelves are spaced about 1" apart
and usually staggered 90 degrees, although often I can't get that stagger
or 1" space depending on sizes of pots I'm doing and it never seemed to
make any difference., But, DON'T push them over to touch sides as some
might tell you. Touching together ok, but blocking flames up side not
The two biggest keys I found were
Use a baffle shelf at 1 1/2" from inside of top vent. I use an old 1/2
shelf from it that I ruined, or you could use a smaller round/hex shelf if
you desire. My ruined 1/2 shelf works fine, but the 1 1/2" setting I found
was kind of important. It just doesn't work firing without it and if too
close or too far it won't fire even either. I then use a couple small cone
six test kiln shelves for adjusting port air outside on top. They aren't
really even used until late in firing.
The air adjustments on burners are VERRRYYYY important. Once set, never
adjust. Recommendations from the start had me setting them at 1/2" and I
had NO reduction whatever I did, blew it's self out when tried, very noisy.
Michael suggested 1/4" and THAT was the ticket. I couldn't believe the
change. Quiet and reduction achievable. I couldn't believe it.
Now, I fire pretty slow since I have lots of seams in some of my pots and
some good sized. Here's how I fire.
I get up about 6am and start pilot to warm up kiln. Just the pilot and it
warms up a couple hours to about 180-200 degrees before I turn on a low
burner flame. I never go over 250/hr. NEVER. Slow, but I have nothing
ruined. I fire until about 2AMish usually. I'd rather fire longer than
throw out ruined stuff!
I watch pyrometers until about cone 7 then remove them and use peeps to see
cones, in fact, very often I can see top cone pack down through top vent
port if my baffle and cone pack position allow me to do it that firing. My
middle two ports are always plugged (something I didn't do at first).
Now with the air adjustments turned way down on burners I can now adjust
reduction when I want easily with top small shelves across the port and it
doesn't blow its self out like it used to. In fact, next firing I'm going
to tighten the air adjustments even a little more than the 1/4", maybe one
more rotation on threads.
Cones are always easier to see at the top (especially if I can look down
inside) and any temp difference in top to bottom is usually with a hotter
bottom now, but, cones drop almost identical, and a few times when I just
couldn't make out the cones at bottom I used top ones alone and firing was
identical. BTW, I use #5 darkness welding goggles I got at a safety store
for about $8. They work nicer and more comfortable than the old welding
mask I used to use at first. You can also get several kinds of Kevlar
gloves and stainless steel thread gloves at these stores if you need them
for anything, like wood carving.
I'm satisfied with firings now. I should say that ALL I MAKE are bonsai
pots and don't have any fancy glazes that require tricky treatments so I'm
not hampered by that, but now I am getting nicer reduction effects on my
clays that I need to darken up some. I use quite a few different clays,
probably a dozen, and lots of iron, so that in it's self is different than
most people choices of only one or two clays.
To reiterate, the three most important things are, flame spreaders, top
baffle and air plate adjustment.
On Wed, Feb 18, 2015 at 8:29 AM, Deborah Thuman via Clayart <
clayart at lists.clayartworld.com> wrote:
> Who here uses them? What do yours look like? How successful is your design?
> I've got a gas fired, round Olympic kiln. When I fired the antique gas
> fired Olsen at the local university, I had very little difference in heat
> from top to bottom. Cone packs were nearly identical. I'm not getting that
> in the Olympic. Cold bottom, hot top. I contacted Olympic and was told to
> have a 2" gap in the middle between the bottom shelves and a slightly
> smaller gap for the rest of the levels. Didn't solve the problem. Next, I
> talked to one of the people at NM Clay and was told to cover the hole in
> the top of the kiln even 1/4". Didn't solve the problem. Next, I tried
> another suggested solution, moving the shelves so they partly cover the
> hole where the flame comes through. Didn't solve the problem.
> I was told that the flame is going up the side of the kiln and out the
> hole in the lid. That makes sense. I don't mind partly covering the hole,
> but I don't want too much reduction. I wouldn't mind enough reduction to
> make the glaze colors do really cool things... but.... I'm using porcelain
> and a chocolate colored clay. The chocolate clay is ^5 and that's carved in
> stone. Fire that clay to ^6 and you get land fill. Great for the bottom
> shelf. The porcelain is ^6. But... I'm getting way more than a 1 cone
> difference between top and bottom. What worked best for me with the Olsen
> was ^5 down, ^6 moving, lower the gas and try to hold for 30 minutes (any
> more or any less produced ugly results) and then shut everything down.
> I'm seeing some of my glazes (they are all commercial) getting pinholes.
> This is happening more on the bottom shelf than anywhere else in the kiln.
> I suspect my mugs are telling me I need to get the bottom of the kiln a tad
> All suggestions are welcome. I won't be firing the kiln for a few months.
> It's too cold out to work in my summer studio (looks just like my back
> patio). It's too cold to work in my autumn studio (looks just like a tiny
> corner of the garage). There are some issues with moving into the winter
> studio (looks just like the laundry room) - both issues having four paws,
> lots of fur and the ability to jump up onto darned near everything.
> Deb Thuman
> I can honestly say that I was never affected by the question of the
> success of an undertaking. If I felt it was the right thing to do, I was
> for it regardless of the possible outcome. Golda Meir
> MAILMAN_MIMEDEFANG WRAP
> Clayart mailing list
> Clayart at lists.clayartworld.com
Lee 李 Love in Longfellow,Minneapolis, MN USA
"Ta tIr na n-óg ar chul an tI—tIr dlainn trina chéile"—that is, "The land
of eternal youth is behind the house, a beautiful land fluent within
itself." -- John O'Donohue
More information about the Clayart