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First Time Firing On A Small 120V Kiln. What Programs Do You Recommend ?

bisque kiln firing

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#1 kennedy james

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Posted 02 March 2014 - 02:27 PM

so I recently purchased a small 120V kiln to use outside (I have no space inside unfortunately, but I do store it inside when it's not in use)

 

it's the Paragon XPRESS 1193, chamber 11x9 in, 0.56 cu ft

http://www.paragonwe...XPRESS-1193.cfm

it comes with the Sentry Xpress 4.0 Digital 3-Key Controller.

 

I'm a real beginner at ceramics.

 

I did the first firing yesterday at cone 01 with the lid open a few inches for 1 hour as recommended, peephole open and the shelves inside.

 

today I'm doing my first bisque firing.

 

I've read the instructions many times and all I could find online, but I still don't know a few things...

 

it seems that I should vent the kiln in the first stages of the firing, I proped the lid open a few inches and left the peephole open but I'm not sure how long I'm supposed to leave it open. the pieces are really dry (casts that have been sitting on my shelves for weeks). so I figure I would check with a mirror if any steam would come out from the peephole and close the lid around 200°. I saw no steam forming on the mirror at all so I actually closed the lid 25 mn after starting the slow cone 04 program. the temp was about 160° i think.

 

should I have left the lip open longer ? I'm really unsure of the venting time required.

 

I've read that the slow program is recommended for bisque. what are the risks and advantages of doing medium/regular and fast speed ?

 

also, what should be the soaking time ? I've read in a book that porcelain should soak 1 hour.

 

for this first bisque firing I have both porcelain and low fire casts, so I programmed the soaking time for 30mn. should I increase it to 1 hour ? 

 

also, I've read you should always leave the top peephole open, and well, this is a small kiln so there is only 1 peephole. so I'm not plugging it. when should I ever plug it ? the instruction manual is not really clear...

 

in a few days I'm going to do a glaze firing at cone 5 or 6 for the porcelain pieces and a glaze firing at cone 06 for the low firing. do I need to have a venting time at the beginning as well ? if so, how long or at what temp should I close the lid ? I guess I should leave the peephole open during the glaze firing as well. what about the soaking time ? what should it be ?

 

again, what are the advantage and disadvantages of doing slow, medium or fast program during a glaze firing. any recommendation?

 

 

I'm sorry I'm having so many questions but I find many different instructions online and I'm not sure what apply to a small kiln like mine.

 

any help is welcome !

 

 



#2 Benzine

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Posted 02 March 2014 - 03:01 PM

There really is no reason to prop the lid, at all. It used to be necessary, with manual kilns, as this would slow the rate of firing, so that damp wares, would have a chance to dry and not explode. With a digital controller, you can set the kiln to fire slow on its own. You'll still want the peep open, initially, to let moisture out.

What is the soak, during the bisque for?

There should be no need to have anything open, during the glaze firing(s).

The advantage of fast firing, is obviously that it's quick. My class kiln can get to cone 05, in under five hours. I would imagine yours would get there very fast.
The disadvantages are that it could cause some glaze defects, especially if the glaze is fairly wet. Also, some glazes require specific heating and cooling, so a fast glaze, might not work.
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#3 kennedy james

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Posted 02 March 2014 - 03:11 PM

What is the soak, during the bisque for?

 

in the book I have it says "soaking porcelain for 1 hour will burn out any organic materials that could cause pinholing and other glaze faults"

 

it also recommends 15-20 mn soak for low fire



#4 bciskepottery

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Posted 02 March 2014 - 04:39 PM

The small kiln probably heats up fast; so the slow bisque with a hold makes sure any organic materials have time to burn out. And, making sure the organics are burned out -- especially with earthenware -- reduces the likelihood for glaze defects (e.g., pinholes). Also, firing too fast could lead to stress in the wares, resulting in cracks, etc.

For your glaze firing, earthenware generally does better when the glaze firing is a cone lower than the bisque firing; again, to reduce the risk of organics burning out during the firing. If you bisque 04, then glaze 05. For other glaze firings, you want to slow down near the end of the firing (maybe the last 200 degrees) to give the glaze the opportunity to melt evenly -- probably more a concern in a large kiln than a small one, but the good practices you use with one kiln easily carry over to another. For glaze firings, I do a short 5 or 10 minute hold; not enough to push the kiln a cone higher, but enough to ensure an even glaze melt.

If you do not vent the kiln while operating, during your bisque firing you might want to prop the top or remove one plug at least until you are beyond burning off physical water -- that allows the steam an easy path out of the kiln.

#5 kennedy james

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Posted 03 March 2014 - 03:27 PM

If you do not vent the kiln while operating, during your bisque firing you might want to prop the top or remove one plug at least until you are beyond burning off physical water -- that allows the steam an easy path out of the kiln.

 

so I should close the lid after I reach 200°F?







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