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#1 Nelly

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Posted 04 April 2012 - 04:30 AM

Dear All,

I was doing a bisque firing tonight. As usual, I kept the top hole open during firing. Now that it is cooling it is still open. Tomorrow, I will gradually open all three holes when it gets below 400 to hasten cooling.

It occurred to me tonight, what would happen if, when I do my next glaze firing, I closed the top peep hole after I reached top temperature (i.e., including the down ramps) and I was purely in the cooling stage?? I have been taught to always keep this top peep hole open after the firing is done.

My rationale is that it would contain the heat and make the cooling process slower and have an effect on the resulting glaze.

Has or does anyone close the top peep hole after they finish a glaze firing? Will this affect my glaze? Will it cause an over melt?

Please know I am using stone ware and am using simple matt glazes.

Nelly

#2 Denice

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Posted 04 April 2012 - 08:29 AM

I was taught to leave the top peep hole open also, but sometimes I would close it if I had some work close to the top of the kiln, I would only put a peep hole plug in it at the very end of the firing, I know it shouldn't make any difference but it made me feel better. When I was in college the head professor was working in primary colors low fire glazes electric, he would leave all of the plugs out during the firing, he thought this gave him brighter colors. I tried it a couple of times but it didn't seem to make any difference in C6 glazes and it took longer to fire. Denice

#3 Nelly

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Posted 04 April 2012 - 08:48 AM

I was taught to leave the top peep hole open also, but sometimes I would close it if I had some work close to the top of the kiln, I would only put a peep hole plug in it at the very end of the firing, I know it shouldn't make any difference but it made me feel better. When I was in college the head professor was working in primary colors low fire glazes electric, he would leave all of the plugs out during the firing, he thought this gave him brighter colors. I tried it a couple of times but it didn't seem to make any difference in C6 glazes and it took longer to fire. Denice


Dear Denise,

I never use plugs. What is the difference between a plug and closing the holes?? I have seen these old ceramic plugs but never knew why they were used. I do sometimes use bright slips under a clear glaze. Perhaps I will try your professors trick some day over the summer to see how it turns out. Thank you for your response.

Nelly

#4 Pres

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Posted 04 April 2012 - 09:01 AM

Dear All,

I was doing a bisque firing tonight. As usual, I kept the top hole open during firing. Now that it is cooling it is still open. Tomorrow, I will gradually open all three holes when it gets below 400 to hasten cooling.

It occurred to me tonight, what would happen if, when I do my next glaze firing, I closed the top peep hole after I reached top temperature (i.e., including the down ramps) and I was purely in the cooling stage?? I have been taught to always keep this top peep hole open after the firing is done.

My rationale is that it would contain the heat and make the cooling process slower and have an effect on the resulting glaze.

Has or does anyone close the top peep hole after they finish a glaze firing? Will this affect my glaze? Will it cause an over melt?

Please know I am using stone ware and am using simple matt glazes.

Nelly


I leave most of my plugs out up to red orange heat during a bisque. then I put all in except for the top one til yellow orange. Then shut down kiln at ^06 and leave all plugs in to slow the cool. I do not use a kiln setter, and only use a witness cone pack for bisque. Glaze the same. I learned to use color of kiln heat years ago to approximate my temperatures. Most of the kiln gasses are gone much earlier than 1200F with quartz inversion just getting over.

Simply retired teacher, not dead, living the dream. on and on and. . . . on. . . .                                                                                 http://picworkspottery.blogspot.com/


#5 Mark C.

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Posted 04 April 2012 - 10:21 AM

I leave my plugs in always.
I crack the lid on the start up of a bisque and then close it when past 800 degrees.
I do not glaze fire in an electric but wonder why the plugs would be left out (evil spirits release???) I have no idea why .Especially when most use the new fan vented exhaust gizmos.
Mark
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#6 Diana Ferreira

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Posted 04 April 2012 - 10:40 AM

Ok, just to confuse you guys :-) I am going to use Celcius as measurement of temperature ...

I leave my top bung hole open for a bisque firing till my kiln reaches 600C. this allows all moisture to evaporate, and make sure no damage to my elements. For a glaze firing, I keep it open to about 200C.

If I am desperate to unpack a kiln, I will open the top bung at about 220C. And the door bung at about 180C.
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#7 TJR

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Posted 04 April 2012 - 11:11 AM

I leave the top bung out for the first two hours of the firing, especially for a bisque. This allows your moisture from glazes and clay body to escape. It is also easier on your elements and less corrosive if the moisture can get out. Then I put all spies in and fire her up. If the top spy hole plug is left out for the duration of the firing, your firing will be slower and cost you muchoe more electricity.[and time].I do not think that your colours would look better because of the spies being left out. Possibly commercial reds might be an exception. They can be tricky!
TJR.

#8 Nelly

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Posted 04 April 2012 - 11:49 AM

I leave my plugs in always.
I crack the lid on the start up of a bisque and then close it when past 800 degrees.
I do not glaze fire in an electric but wonder why the plugs would be left out (evil spirits release???) I have no idea why .Especially when most use the new fan vented exhaust gizmos.
Mark


Dear Mark,

I am firing in a brand new just off the line ConeArt electric Kiln. When you say you keep your plugs in always, would that be similar to me keeping my peep holes shut. I used to candle with the lid open for a couple of hours with all peep holes open just to drive off last little bits of water.

Interesting that you crack at 800 degrees. I have never tried doing it at the high of temperature. I was told that you should never open the lower two peep holes until it is around 400 or the temperature of an oven.

Anyway, I think this could be a little more complicated and involves many factors (i.e., effect of glaze on the thickness of the ware and rapid cooling causing cracking, how different glazes react etc.).

I am off for the summer, so I will likely do some gentle experiments.

I must research what kiln plugs area and their function (i.e., whether they are the same thing as peep holes that slide on a hinge).

Thank you Mark.

Nelly

#9 Nelly

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Posted 04 April 2012 - 11:53 AM

I leave the top bung out for the first two hours of the firing, especially for a bisque. This allows your moisture from glazes and clay body to escape. It is also easier on your elements and less corrosive if the moisture can get out. Then I put all spies in and fire her up. If the top spy hole plug is left out for the duration of the firing, your firing will be slower and cost you muchoe more electricity.[and time].I do not think that your colours would look better because of the spies being left out. Possibly commercial reds might be an exception. They can be tricky!
TJR.


Dear TJR,

Leaving the top peep hole open is exactly what I did yesterday. I wanted to candle for two hours but with this new computerized kiln, the "slow bisque" setting moves really slowly. My large platters were bone dry so I thought, what the heck!!!

Given that candling is my usual practice, I will be trying to achieve this in a ready to go digital formula.

Good reminder though about the corrosion on the wires. I forgot about that.

Thank you.

Nelly

#10 Mark C.

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Posted 04 April 2012 - 09:45 PM

Peep holes and spy plugs-
The plugs stay in the spy hole as I put a soft brick wedge that holds the top (lid) open for a bisque-this lets the moisture out-when I say 800 I really mean when I get around to checking it. I set my ramp on medium (speed of temp. climb) and if I remember to check it at 400 600 or 800 whatever I close the lid when I walk by -taking the wedge out. Kiln is outside of studio so I tend to forget about it. its on a kiln setter and timer (not electronic new style)
so when I drop lid I ramp it up a to a higher climb as I know its all dry inside and it turns off on its own with a backup.
I tend to bisque in my gas kilns more and electrics are just for last minute extras or overflow as Electricity costs more than gas for me.
The lid cracked open lets way more moisture out than a tiny spy plug.
I do not bisque by cone anymore in gas kilns-just look at it and both digital pyros- You get a feel for this over the years.
Mark
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#11 TJR

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Posted 05 April 2012 - 09:50 AM


I leave the top bung out for the first two hours of the firing, especially for a bisque. This allows your moisture from glazes and clay body to escape. It is also easier on your elements and less corrosive if the moisture can get out. Then I put all spies in and fire her up. If the top spy hole plug is left out for the duration of the firing, your firing will be slower and cost you muchoe more electricity.[and time].I do not think that your colours would look better because of the spies being left out. Possibly commercial reds might be an exception. They can be tricky!
TJR.


Dear TJR,

Leaving the top peep hole open is exactly what I did yesterday. I wanted to candle for two hours but with this new computerized kiln, the "slow bisque" setting moves really slowly. My large platters were bone dry so I thought, what the heck!!!

Given that candling is my usual practice, I will be trying to achieve this in a ready to go digital formula.

Good reminder though about the corrosion on the wires. I forgot about that.

Thank you.

Nelly


Nellie;
Lucky you to have a brand new Cone Art kiln. I had to sell mine when I moved out of my previous studio. I did not want to lug it down the stairs. Hey, that reminds me, I am still owed $150.00 bucks for it. I am not that familiar with computerized kilns, although I used one when I taught a course called Ceramics for Art Educators at the University of Saskatchewan in Saskatoon. [hard to spell] I know that you can reprogram those babies to fire faster though. That staining on your nice metal kiln wall comes from moisture leaking out of the kiln lid. Better to direct it out of the spy holes.Enjoy your summer. I am still slogging it out at high school until June 30.
TJR

#12 Nelly

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Posted 05 April 2012 - 02:34 PM



I leave the top bung out for the first two hours of the firing, especially for a bisque. This allows your moisture from glazes and clay body to escape. It is also easier on your elements and less corrosive if the moisture can get out. Then I put all spies in and fire her up. If the top spy hole plug is left out for the duration of the firing, your firing will be slower and cost you muchoe more electricity.[and time].I do not think that your colours would look better because of the spies being left out. Possibly commercial reds might be an exception. They can be tricky!
TJR.


Dear TJR,

Leaving the top peep hole open is exactly what I did yesterday. I wanted to candle for two hours but with this new computerized kiln, the "slow bisque" setting moves really slowly. My large platters were bone dry so I thought, what the heck!!!

Given that candling is my usual practice, I will be trying to achieve this in a ready to go digital formula.

Good reminder though about the corrosion on the wires. I forgot about that.

Thank you.

Nelly


Nellie;
Lucky you to have a brand new Cone Art kiln. I had to sell mine when I moved out of my previous studio. I did not want to lug it down the stairs. Hey, that reminds me, I am still owed $150.00 bucks for it. I am not that familiar with computerized kilns, although I used one when I taught a course called Ceramics for Art Educators at the University of Saskatchewan in Saskatoon. [hard to spell] I know that you can reprogram those babies to fire faster though. That staining on your nice metal kiln wall comes from moisture leaking out of the kiln lid. Better to direct it out of the spy holes.Enjoy your summer. I am still slogging it out at high school until June 30.
TJR


Dear TJR,

Yes, I am lucky to have a new Cone Art Kiln. I totally love it. Yesterday, when I opened it, I knew (even before going into it) that it the platters would be fine. The climb up in temperature was soooo gentle. Having said that, I was up until 2am waiting for it to go off so I could sleep. It is amazing how much cleaning you can do while waiting for a kiln to finish. I know I could likely have just left it but I thought rather than not know if it was off when I went to bed, I would make sure. I now need a kiln book to record firings. I wonder if I can find a recording page created on line that I could use. I will check.

Nelly

#13 Nelly

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Posted 05 April 2012 - 03:02 PM

http://www.paragonwe...ing_Records.pdf

;)



Hey Slurrious,

That is one slick chart. I will definitely print this out. At my old studio we just had a book with boxes. It contained the date, time started, increase ramps, and hold times. This chart provides a visual of the whole firing. I like that--I am visual!!!

Great chart finding Slurrious. I will print out a bunch of copies and start my binder.

Gawd, I love this site.

Nelly

#14 neilestrick

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Posted 05 April 2012 - 03:29 PM

In kilns without a downdraft vent, most manufacturers recommend leaving the top spy/peep hole open for the entire firing, to allow gases and water vapor to escape. Leaving more than one open will just waste energy as you are also losing a certain amount of heat as well. Many of the old manuals say to leave the lid cracked for the first part of the firing, but I have never seen that to be necessary, and is just an energy waste in my opinion. The only time I would see propping the lid during the firing as necessary is in kilns that do not have low-med-high switches or infinite switches, but rather just on/off switches (old Evenheat kilns for example). Propping the lid in those cases would slow down the firing at the beginning and prevent explosions, since the elements are always on high when on.

Kilns with downdraft vents should always have all the peep/spy holes closed during the firing. Otherwise the vent will not work properly, since the spy hole is much too large for the small amount of draft created by the vent. Some manufacturers will have holes in the kiln lid for the vent to pull air through (Skutt). Others do not put holes in the lid (L&L), since round kilns are dry stacked and generally drafty enough for the vents to function properly. That said, my 18" L&L did require lid holes since the small kilns tend to be much tighter and less drafty than the larger ones.

Neil Estrick
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Owner, Neil Estrick Gallery, LLC
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neil@neilestrickgallery.com





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