James Stone on tue 7 oct 03
I got into potter mostly to design and make my own bonsai
pots and I'm a lurker.
Against Dale's advice (for the record ;^)>) I purchased an
Olympic gas (1827?) as my first kiln- mostly based on price
( I guess I got the stripped down Kia?) and cost of running
it...
Dale's advice came mostly from the standpoint of not having
any harsher a learning curve than necessary- a nice
controller equipped electric would probably be infinitely
easier! An electric would have meant almost rewiring my
whole house and I do like to be obstinate.
Everything I know comes from trial and error, a few classes,
what I've read (mostly ClayArt), and from generous potters
like Dale.
I've noticed a few spider cracks in the lid but nothing
"upsetting"; I rationalized with flames like that roaring
around they're to be expected.
I've had no problems bisque firing. After firing it to ^6
about 4 or 5 times, I too have noticed the same cool bottom
problems attributing them to what Dale had said- it would
take a lot more practice to really learn how to control a
gas kiln, loading, etc.
The first time went the best, although it took something
like 12 hours start to finish. I realize now that I was
probably in reduction a lot of the time as I was playing
with blocking the vent and the peeps and the burners...
Once I got it to wher eit seemed "efficient to my eyes, I
finally left it alone the cones dropped.
The next run I tried, I shut down after like 12 hours of
"playing"... then I learned about the "magic baffle". I'm
using an "oversized" shelf (i.e., about 17" wide) that only
leaves finger room from the sides.
The one success I did have- went perfect and fast- like 6-8
hours, maybe a bit more, after candling -was with the baffle
shelf used as a normal shelf about 1/2 to 2/3 up from the
bottom. At the time it seemed to me that that was where I
wanted the flame/heat to stay so I should knock it down.
This is the one that taught me about notes- I didn't really
take any so I don't have details as to how I packed and
distances and all that...
To see if I could better my results, I've tried it twice
more about 3" from the top with different packing
arrangements which did not seem to solve the problem.
Both resulted in an overfired top (^7 fully dropped)
underfired bottom (^5 ever so slightly bent).
The first went about 10 hours. The second was shut off
after 12 hours. The first was with all 3 rings, then
thinking maybe size did matter, the second was with only 2
rings... This meant the peep did not give a view of the top
half, only over the baffle; I had no idea the top was over
fired till I opened it up. I kept hoping those bottom cones
would go. The inside just never looked right - like it did
when the dang thing worked.
So now as I seek the Holy Grail, I write down all the shelfs
and posts used, pot placement, weather, etc...
I wrote my difficulties off to inexperience so I've not
really sought "satisfaction". I'd enjoy getting this worked
out also.
Sincerely,
Jim Stone
Galveston TX
Paul Vernier on wed 8 oct 03
Dale and Charles and I have exchanged emails on this subject several times. We all do many things to get these kilns to fire as we would like them to.
So, I was thinking, what do I believe to be the key firing processes and setup routines, that allow me to fire even and to temperature.
So a brief list may help the others out there wrestling this little beast.
In order of what I consider to be important.
1) A dual thermocouple pyrometer. This will give you fairly immediate feedback on what affect your last adjustment had on the temperature and the top/bottom differential.
2) Use the damper, (a piece of shelf on top of kiln over the flue) to adjust heat from top to bottom. For an updraft, opening the damper brings heat up, closing pushes the heat down (up until the point you are getting more that mild reduction). These adjustments should be made in very small increments. For example, 1/16 of an inch evenly across the total opening. Then watch the pyrometer.
3) This is a little easier in my case as I fire with propane and have an adjustable regulator. Use gas pressure to induce reduction. You can get relatively good reduction using this method. for heavy reduction you will have to use the damper as well. Don't adjust the primary air rings on the burners.
4) Baffle shelf at the top. Shelf can be smaller than your normal shelves. Place about 1 1/2 inch from lid. This get touchy with large pieces on top. I am researching a design to permanently attach a baffle shelf to the lid. Hopefully have a first test soon. Any suggestions out there?? I do fire to cone 10
5) Bottom shelf four inches off bottom. I use 4 hard bricks to place the bottom shelf. I set the bricks so the center burner is directed to the sides away from the outside burner placement.
Stacking? I have stacked many different ways and within reason this has not affected my firing. So, I would concentrate on the others suggestions.
Spend the money and get the pyrometer. You need this visibility to understand your kiln. Sell it on Ebay after you master this creature.
Hope you all have better success with your firings.
An yes I have cracks. I mean my kiln lid does.
Paul in Santa Cruz, CA where we are saying, "When is Arnold going to Terminate the deficit?"
Paul Vernier
(408) 525-5763 Pager (408) 322-7452 or pvernier@epage.cisco.com
Program Manager Architecture Baselines 375 East Tasman
https://mco.cisco.com/eng/eng-ops/ab/index.html San Jose, CA 95134-1706
Technical Operations Cisco Systems
dalecochoy on thu 9 oct 03
----- Original Message -----
From: "Paul Vernier"
Subject: Re: Olympic Gas Kiln Lid Cracks and Firing Problems
> Dale and Charles and I have exchanged emails on this subject several
times. We all do many things to get these kilns to fire as we would like
them to.
Yes, Paul's been a big help.! It's great to sort through everyones "trial
and errors". Really helps.
> So, I was thinking, what do I believe to be the key firing processes and
setup routines, that allow me to fire even and to temperature.
> So a brief list may help the others out there wrestling this little beast.
ditto, ditto, and ditto on suggestions.
!
> In order of what I consider to be important.
> 1) A dual thermocouple pyrometer. This will give you fairly immediate
feedback on what affect your last adjustment had on the temperature and the
top/bottom differential.
Yep, I don't know how it can be done without one. Makes corrections soooo
easy.
> 5) Bottom shelf four inches off bottom. I use 4 hard bricks to place the
bottom shelf. I set the bricks so the center burner is directed to the sides
away from the outside burner placement.
I use the 4" posts but don't understand "center" burner from "outside
burner"? Mine has 4 burners around outside, no "center" burner. Is this an
old setup or am I just reading wrong.?
> An yes I have cracks. I mean my kiln lid does.
Well, this is still a sore point with me and I don't consider this "NORMAL"
to expect, I don't care if everyone who owns an Olympic kiln has them. I
consider it a FLAW IN DESIGN! which I won't confuse with "Expected Normalcy"
and I won't be satisfied until Olympic replaces my top! I know Rob Haugan
monitors the list so he's got my opinion!. He posted that they stand behind
their products that they've made for 35 years....so, where's my top???
I will most certainly gratefully acknowledge a manufacturers satisfying
result to my problem, just as I will certainly complain about it and pass
on my complaints!
Regards,
Dale Cochoy
Robert Huskey on thu 9 oct 03
I envisage a solution to the problem using a small sheet of 1/2 in.
fiberboard , kanthal wire , 1 1/2 in cubes of soft brick with small holes
drilled through , and some small ceramic buttons.
Bob Huskey --- Tallahassee , Fl.
----- Original Message -----
From: "Paul Vernier"
.
>
> 4) Baffle shelf at the top. Shelf can be smaller than your normal shelves.
Place about 1 1/2 inch from lid. This get touchy with large pieces on top. I
am researching a design to permanently attach a baffle shelf to the lid.
Hopefully have a first test soon. Any suggestions out there?? I do fire to
cone 10
dalecochoy on fri 10 oct 03
> ----- Original Message -----
> From: "Paul Vernier"
> > 4) Baffle shelf at the top. Shelf can be smaller than your normal
shelves.
> Place about 1 1/2 inch from lid. This get touchy with large pieces on top.
I
> am researching a design to permanently attach a baffle shelf to the lid.
> Hopefully have a first test soon. Any suggestions out there?? I do fire to
> cone 10
An academic idea Paul, although I'd worry about any further extra weight on
that single rinky-dink lid support. You might also need to install one on
the other side. Then you'd be bumping it all the time loading/unloading.
It's always thought provoking when you are trying to "Jesse James Monster
Garage" something!
My wife keeps calling me that everytime I "remodel" something.
Dale "An old chopper builder" Cochoy
Norman van der Sluys on sun 12 oct 03
I did a glaze fire this past week. This was not the most even firing in
my 28r by any means. This time the top was cold - about 1 1/2 cones
colder. I used a baffle on the top 1 1/2" and staggered all shelves
but the bottom one. I crash cooled to 1100 dig. C and soaked for 1 1/2
hours.
Got some good results but the soak did nothing for the unevenness. I
have been having trouble with the flame from the center burner (my kiln
has 3) scorching the pots toward the center of the bottom shelf -
cratered glaze areas, and in my last bisque firing it cracked a bowl.
So for next time I will try the deflector idea and raise the bottom
shelf, now at 3" up to 5.
Any of you guys have further suggestions?
dalecochoy wrote:
>
> ----- Original Message -----
> From: "Paul Vernier"
> Subject: Re: Olympic Gas Kiln Lid Cracks and Firing Problems
>
> > Dale and Charles and I have exchanged emails on this subject several
> times. We all do many things to get these kilns to fire as we would like
> them to.
>
> Yes, Paul's been a big help.! It's great to sort through everyones "trial
> and errors". Really helps.
--
Norman van deer Slues
Benin Pottery
Near the shore of Lake Michigan
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