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#21 DAY

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Posted 20 June 2012 - 02:00 PM

Day,

Good looking dishes. Can you tell me how you do the dish in the lower left? What do you use to color the leaf.

Bobg

leaf colors are Brooklyn Red slip, rutile, iron oxide. Green is mason stains & ball clay on Standard 266.

#22 LilyT

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Posted 20 June 2012 - 05:25 PM

Yes, thank you for taking the time and sharing all the detail and
intricacies to consider while making these! They are wonderful,
and it's nice to know people express their appreciation by buying.

I'm curious about your firing costs if you don't mind
sharing about that? For my converted electric kiln it takes 2 gal
propane ($8) to bisque fire about a 3 cu ft space. About
6 gal ($24) to go to ^5 and firedown to 1500F, roughly 8 gal to
^10 plus scrap wood though. It would probably be more efficient in
a bigger kiln. especially if I could complete 48 pots in less than an
hour! If you have ideas about efficiency I'm sure we could all benefit
from hearing about it :-).

-Lily


#23 Mark C.

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Posted 20 June 2012 - 10:59 PM

After losing a lot of typing as this program logs you out in about 2 seconds-my patience is being tested again as it almost always is on this site due to poor software.

Am I the only one who thinks this program needs upgrading??

As a frequent poster I hope the powers that be get this fixed,as I am tired of doing it all in word and pasting-I post a lot on other boards with none of these issues a anywhere else but here-come on guys and gals fix this.

Rant over

(This above discussion moved to the "Business" section) - JBaymore

Lily

As far as efficiency my gas bill which I rarely ever dissect was 139$ last month-April 20 thru May 18th-That bill reflects one bisque and one glaze in my 35 cubic foot downdraft car kiln and one glaze firein my 12 cubic foot updraft.

This was a very slow firing period as I was just getting to speed after wrist surgery. Now I’m firing a bisque and glaze every week-past 3weeks with a little kiln glaze load as well-The bill which should come soon Iwill post the amount-They read meter during early past of a glaze fire so it’s a mixed bag.

I always think gas is cheap even when my bill is 400$ as it takes just a few pots to cover it really. Work efficiently in every part of ceramics comes with 39 years of doing it full time-learning to always have more work than will fit into fire is key as well as stacking small pots into other pots tumble stacking in the bisque and firing the nooks and crannies every firehelps. These shelves (advancers) give my an extra 1 to 2 feet of stacking space every glaze fire as well-As I fire a lot they pay for them selves very quickly even at 200$ apiece.

Heres my 2 weeks ago glaze fire as well as today’s spoon rundone by my assistant-she throws them slower than me but they are nicer thanmine.

Mark

Attached Files


Mark Cortright
www.liscomhillpottery.com

#24 LilyT

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Posted 21 June 2012 - 09:53 AM

...



As far as efficiency my gas bill which I rarely ever dissect was 139$ last month-April 20 thru May 18th-That bill reflects one bisque and one glaze in my 35 cubic foot downdraft car kiln and one glaze firein my 12 cubic foot updraft.

This was a very slow firing period as I was just getting to speed after wrist surgery. Now I’m firing a bisque and glaze every week-past 3weeks with a little kiln glaze load as well-The bill which should come soon Iwill post the amount-They read meter during early past of a glaze fire so it’s a mixed bag.

I always think gas is cheap even when my bill is 400$ as it takes just a few pots to cover it really. Work efficiently in every part of ceramics comes with 39 years of doing it full time-learning to always have more work than will fit into fire is key as well as stacking small pots into other pots tumble stacking in the bisque and firing the nooks and crannies every firehelps. These shelves (advancers) give my an extra 1 to 2 feet of stacking space every glaze fire as well-As I fire a lot they pay for them selves very quickly even at 200$ apiece.

Heres my 2 weeks ago glaze fire as well as today’s spoon rundone by my assistant-she throws them slower than me but they are nicer thanmine.

Mark



Hi, Mark, I was just thinking "I wonder what editing problem Mark was seeing, while typing in
my response, and I lost the page, lol."

Anyhow, thanks for sharing your numbers and thoughts about firing costs! That's
really very effective. I also like the way you think about how it only takes a few
pieces to cover the entire firing costs. In my day job, I also like to think about
where the breakeven point is every month, and then think about everything else
that comes in as net income. It's psychologically more appealing.

Your glaze fire picture is glorious. And all those pretty spoonrests. I love
the look of glazed items, but a plethora of greenware or bisqueware is also
so appealing, I can just sit and look at the forms for hours. I've sometimes
wondered whether people would buy bisqueware...

Good to know that you're recovering from wrist surgery, was that due
to doing pottery? I know a lot of people with carpal tunnel and back
injuries from clay work.

Lily




#25 JBaymore

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Posted 21 June 2012 - 09:54 AM

Work efficiently in every part of ceramics comes with 39 years of doing it full time-learning........


There is the key. NOTHING takes the place of experience and education in ANY field.


These shelves (advancers) give my an extra 1 to 2 feet of stacking space every glaze fire as well-As I fire a lot they pay for them selves very quickly even at 200$ apiece.


In addition to the additional physical stacking space, the use of what are known as "low termal mass refractories" saves you on firing costs. My 3/4 " thick 18" x 18" traditional silicon carbide shelves are HEAVY. My 1/2" thick nitride bonded ones are much lighter. My 1/4" thick Advancers are featherweight!

A good part of the heat energy used in periodic kilns (they type we fire) to bring them up to temperature is used to heat the kiln structure and the kiln furniture...... not the wares themselves. Less weight on silicon carbide (type) shelving material in the kiln means less energy is used to heat the shelves. (This is why industry uses ceramic fiber kilns and low mass furniture.... plus when you add in the concept of continuous kilns........ a HUGE energy usage savings.)

A win/win. More space and less heat energy used.

best,

.......................john
John Baymore
Immediate Past President; Potters Council
Professor of Ceramics; New Hampshire Insitute of Art

http://www.JohnBaymore.com

#26 LilyT

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Posted 21 June 2012 - 09:56 AM

I had to go back and look at your glaze firing picture again. Your glazework
is so beautiful. As are the forms. Each piece is like a gleaming treasure.
-Lily

#27 Mark C.

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Posted 21 June 2012 - 10:09 PM

To get this post back on track-I dug up another gas bill and checking my kiln logs (logging all fires has been a good thing for my whole life in ceramics) answering your fuel cost questions.
My natural gas bill for march 21st thru 4/19 was 227$
That was for for two kiln loads in car kiln -Thats what I call them for 2 bisques and 2 glaze loads as well as one glaze fire only in small 12 cubic footer.
I can do a what's one glaze fire cost as my summer production ramps up for a big show.
Mark


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#28 LilyT

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Posted 21 June 2012 - 11:03 PM

Hi, Mark,
So nice of you to go through the trouble to dig up and
correlate records. Also, impressed that you keep records
and not misplace them after a few years :-).
It seems that your total energy costs run slightly less than $3
per cu ft of finished ware. Whereas mine runs about $10
per cu ft. Bigger kilns are more fuel efficient I would presume?
Also, I bet that you are more efficient firing than I am.
All these details are interesting to know, I bet this is helpful
for other real potters (like yourself and unlike yours truly).
I know in some parts of the world, people can come by scrap
wood and other more inexpensive materials to run a firing. But
of course, then that takes your attention and time away
from making pots to fiddle with a lot of cost savings measures.

On an aside, I am looking forward to reading more about your
glazing and firing process with the spoonrests (oh yeah, this
was about spoonrests!). And I'm very interested in how you
get such gorgeous colors. (I know the shapes3 come from talent and
hard work)

:-)
Lily



#29 Mark C.

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Posted 21 June 2012 - 11:27 PM

The car kiln is home made by me. Soft brick arch roof and inner walls mostly K26s and a few K28s around the hard brick areas. It used to be k-23 but they wear out fast and I've had to rebuild it-as I fire this about 35-40 glaze fires a year with the same amount of bisques -I used to fire more but am slowing down as I age. The door of car is all fiber and two side walls are covered with fiber-the floor and fire box and flue is hard brick.The door is metal and the kiln roof has fiber over arch of soft bricks-the outer walls are hard brick as thats what I like to see-its more a visual durable outer layer-It takes about 12 hours to high fire from a cold. I go very fast up to my reduction temperature then it slows a bit-the slowest part is when the glaze melt is occurring.
larger kilns can cost less to get more ware from as you noted-my little 12 cubic costs less than 12$ to glaze fire.

Sound like you know your exact costs-I always have kept records of firing-that way you know what and when things happen-and can learn from them.
I figure firing costs every few years but really do not get to caught up in it-what matters is clay makes more than it costs in the long run. I's a living for me-So its need to make money when its all done.The cost of a BTU is something I always look at on the bill.
Mark
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#30 LilyT

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Posted 21 June 2012 - 11:40 PM


Work efficiently in every part of ceramics comes with 39 years of doing it full time-learning........


There is the key. NOTHING takes the place of experience and education in ANY field.


These shelves (advancers) give my an extra 1 to 2 feet of stacking space every glaze fire as well-As I fire a lot they pay for them selves very quickly even at 200$ apiece.


In addition to the additional physical stacking space, the use of what are known as "low termal mass refractories" saves you on firing costs. My 3/4 " thick 18" x 18" traditional silicon carbide shelves are HEAVY. My 1/2" thick nitride bonded ones are much lighter. My 1/4" thick Advancers are featherweight!

A good part of the heat energy used in periodic kilns (they type we fire) to bring them up to temperature is used to heat the kiln structure and the kiln furniture...... not the wares themselves. Less weight on silicon carbide (type) shelving material in the kiln means less energy is used to heat the shelves. (This is why industry uses ceramic fiber kilns and low mass furniture.... plus when you add in the concept of continuous kilns........ a HUGE energy usage savings.)

A win/win. More space and less heat energy used.

best,

.......................john


Good points noted. Buying better equipment can be cost saving in multiple ways.

#31 LilyT

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Posted 21 June 2012 - 11:54 PM

The car kiln is home made by me. Soft brick arch roof and inner walls mostly K26s and a few K28s around the hard brick areas. It used to be k-23 but they wear out fast and I've had to rebuild it-as I fire this about 35-40 glaze fires a year with the same amount of bisques -I used to fire more but am slowing down as I age. The door of car is all fiber and two side walls are covered with fiber-the floor and fire box and flue is hard brick.The door is metal and the kiln roof has fiber over arch of soft bricks-the outer walls are hard brick as thats what I like to see-its more a visual durable outer layer-It takes about 12 hours to high fire from a cold. I go very fast up to my reduction temperature then it slows a bit-the slowest part is when the glaze melt is occurring.
larger kilns can cost less to get more ware from as you noted-my little 12 cubic costs less than 12$ to glaze fire.

Sound like you know your exact costs-I always have kept records of firing-that way you know what and when things happen-and can learn from them.
I figure firing costs every few years but really do not get to caught up in it-what matters is clay makes more than it costs in the long run. I's a living for me-So its need to make money when its all done.The cost of a BTU is something I always look at on the bill.
Mark


Hi, Mark,

My kids and I were just discussing today how a car kiln would be so much easier
to load, and then to get everything done at once. I'll have to share your construction
details with them.
I glaze fire as fast as possible to temperature (about 5 hours to ^10, 3-1/2 to ^5), my 3 cu ft kiln has
one venturi. Then hold at temp and do a controlled firedown for 6 hours. After that the
kiln is so small that it cools to 100F in 12 hours.
I totally agree that it's best not to get too caught up in the cost details, there's only so
much time and energy a person has, and it should be used to create. Still, it's
interesting... especially if one has kids to raise and a house or car to pay off.

How long did it take you to build your car kiln? Are you a welder also?

-Lily

#32 JBaymore

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Posted 22 June 2012 - 08:39 AM

I am going to try to split off the "forum software issues" postings from this thread into a separate thread. Then move that new htread to a different forum section (it clearly is not an "in the studio" topic).

Wish me luck.

Moved to "Business" section.

best,

...........................john
John Baymore
Immediate Past President; Potters Council
Professor of Ceramics; New Hampshire Insitute of Art

http://www.JohnBaymore.com

#33 Mark C.

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Posted 23 June 2012 - 01:19 PM

Lily
Todays gas bill 271$
includes
3 car kiln bisques
3 Car kiln glazes
a few hours of another glaze as they read meter during fire
2 glaze fires in 12 cubic footer

Still seems cheap to me.
129 cubic feet of finished glaze ware for 271$
Mark
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www.liscomhillpottery.com

#34 LilyT

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Posted 24 June 2012 - 01:53 AM

Lily
Todays gas bill 271$
includes
3 car kiln bisques
3 Car kiln glazes
a few hours of another glaze as they read meter during fire
2 glaze fires in 12 cubic footer

Still seems cheap to me.
129 cubic feet of finished glaze ware for 271$
Mark


Mark,

Still seems cheap to me, too. But the ultimate measure is that your beautiful
work is produced.

Thanks for sharing!

I'm also curious about how long it took you to build your wonderful
car kiln. How many burners does it use? Did you design it all
yourself? I know you mentioned rebuilding it, so 'm sure you
at least modified it to work better for you.

I am going to throw some spoonrests tomorrow :-)

-Lily



#35 Mark C.

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Posted 27 June 2012 - 01:59 AM

I built this so many years ago in the 70's then rebuild in the early 80s after a potter partner split up.
It was over a month to two-cement pad walls ,car, wielding-sprung arch -chimney
Then again in the late 90s that time I wore out all the k23 bricks from use
I also redid the chimney about 7 years ago as it had had it after 3 earthquakes and it was made from leftover stuff-now its all new and tight-the top 15 feet are 12 inch diameter stainless thick wall pipe-I like stainless for stacks it never wears out even on my salt kiln looks as new as the day I put it up.
For many years this was fired for over 40-45 glaze loads a year and the same amount of bisques-that adds up as the decades slide by and wears on the refractories.I went thru silicone carbide shelves then dry press high alumina English shelves now for the past 12 years or more Advancers. All my shelves are 12x24s. Average load is 35 shelves.
I tried lined fiber on the roof for about 5 years and tore that out and re-sprung the arch with k 26 and k 28s
The burners are small 75th btu and I have 8 of them (a pair per burner port) with 4 ports-no safety stuff-all just old school seat of the pants ball valves-no pilots-Just the real deal. I light one set for candling bisque .
No computers or ramping just common sense firing-old school-I do have an oxygen probe and digital pyro. on this kiln as well as another but can fire it all with out that stuff in my sleep-after all I fired so many kilns without any of that new tec stuff back in the day its like learning to ride a bike.
I do like the extra info and it does make it easier
with a kiln like this its very little to do for a fire once its above red heat or in reduction-just watch the cones and turn it off.You are connected to it more than say a computerized electric with auto shut off.
Mark

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#36 LilyT

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Posted 27 June 2012 - 05:58 PM

I built this so many years ago in the 70's then rebuild in the early 80s after a potter partner split up.
It was over a month to two-cement pad walls ,car, wielding-sprung arch -chimney
Then again in the late 90s that time I wore out all the k23 bricks from use
I also redid the chimney about 7 years ago as it had had it after 3 earthquakes and it was made from leftover stuff-now its all new and tight-the top 15 feet are 12 inch diameter stainless thick wall pipe-I like stainless for stacks it never wears out even on my salt kiln looks as new as the day I put it up.
For many years this was fired for over 40-45 glaze loads a year and the same amount of bisques-that adds up as the decades slide by and wears on the refractories.I went thru silicone carbide shelves then dry press high alumina English shelves now for the past 12 years or more Advancers. All my shelves are 12x24s. Average load is 35 shelves.
I tried lined fiber on the roof for about 5 years and tore that out and re-sprung the arch with k 26 and k 28s
The burners are small 75th btu and I have 8 of them (a pair per burner port) with 4 ports-no safety stuff-all just old school seat of the pants ball valves-no pilots-Just the real deal. I light one set for candling bisque .
No computers or ramping just common sense firing-old school-I do have an oxygen probe and digital pyro. on this kiln as well as another but can fire it all with out that stuff in my sleep-after all I fired so many kilns without any of that new tec stuff back in the day its like learning to ride a bike.
I do like the extra info and it does make it easier
with a kiln like this its very little to do for a fire once its above red heat or in reduction-just watch the cones and turn it off.You are connected to it more than say a computerized electric with auto shut off.
Mark



Wow, that's pretty prompt construction, it's a lot more complicated than
stacking a bunch of bricks :-). You certainly aren't wary of getting right
in there and fixing it right up. I'd *love* to to build a permanent kiln somewhere
that works well. (I believe the concurrent thread about permitting adequately
goes into why not.) It's awesome that you have 8 burners. I imagine it
would be hard for them to all blow out at the same time without you noticing.
In my experience having an observant and careful person firing
and watching a kiln is superior in every way to leaving a kiln unattended
with a bunch of safety devices.

I'm curious what a truly used up silicon carbide shelf looks like?

I just love the process of firing with gas and wood as compared to switching
an electric kiln on. It sounds like you have the whole process down so
it's like breathing. I still enjoy the dance and the figuring out whether it's
going well from moment to moment. A digital pyrometer has really helped me follow how
hard I'm pushing my kiln - do you find that having an oxygen probe is significantly
more informative than looking at the haziness of the atmosphere inside the kiln?
(or when the temperature rise starts to slow down.) Would you recommend
getting one?

-Lily


#37 Mark C.

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Posted 27 June 2012 - 11:43 PM

I'm curious what a truly used up silicon carbide shelf looks like?




They look about as curved as a banana and are full of cracks
as far as an oxy probe -unless its your living and are doing production I would say no its not worth it-But for me with a glaze load almost weekly it is worth it. What I can tell you is that with a probe you can see the smallest of damper adjustments is a major difference in reduction-We are talking 1/16 of an inch stuff when its in the zone. This is all about reduction firing as thats my life with clay-reduction firing.
Mark
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#38 LilyT

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Posted 28 June 2012 - 12:48 AM

I'm curious what a truly used up silicon carbide shelf looks like?


They look about as curved as a banana and are full of cracks


(...)

Mark


That's so interesting! Does that mean you don't flip your shelves over
between firings? So is there any further use for them? Like lining the
bottom of a wood fire kiln? I was looking for used silicon carbide at one
point to use as an absorption surface for a solar furnace to build with
my kids.

-Lily

#39 Mark C.

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Posted 28 June 2012 - 01:03 AM


I'm curious what a truly used up silicon carbide shelf looks like?


They look about as curved as a banana and are full of cracks

(...)
Mark


That's so interesting! Does that mean you don't flip your shelves over
between firings? So is there any further use for them? Like lining the
bottom of a wood fire kiln? I was looking for used silicon carbide at one
point to use as an absorption surface for a solar furnace to build with
my kids.

-Lily


I bust then into small nurds to add 5/8 to 3/4 of an inch when the stilt is to short. when loading
Mark
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#40 LilyT

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Posted 28 June 2012 - 01:09 AM



I'm curious what a truly used up silicon carbide shelf looks like?


They look about as curved as a banana and are full of cracks

(...)
Mark


That's so interesting! Does that mean you don't flip your shelves over
between firings? So is there any further use for them? Like lining the
bottom of a wood fire kiln? I was looking for used silicon carbide at one
point to use as an absorption surface for a solar furnace to build with
my kids.

-Lily


I bust then into small nurds to add 5/8 to 3/4 of an inch when the stilt is to short. when loading
Mark


How practical. I don't think I've heard the phrase 'nurds' however. Maybe
it's too late for my brain to work.
-Lily







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