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Babs

Cones Do You Bisque The Packs

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Just wondering I have been bisquing the cone packs for my glaze firings, basically because early on I had a few blow in the glaze firing. I realise that the cones may be altered by the heat work done..are they? Or is this step not needed if the clay is completely dry, I fire 150 C/hr after 200 in a glaze firing.

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When I was using the regular cones and I had to make cone pats of clay, I would never bisque them first. I modified the beginning of my schedule to do a 30 minute preheat at around 180F. I also made a ton of pats ahead of time and let them dry for a good week+ before I used them. I never had any explode except the very first one I used and it was still cold to the touch and I didn't know any better.

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When I ws firing reduction I used clay cone packs with 09,04, 5,6,7 cones. I made a spoon to catch the puddle from the 09 and 04 as i took it up tp ^6. I reduced from 09-04 for body color.

 

I usually made them well in advance and poked many holes in the clay. No problems

 

Marcia

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Yeah, don't bother bisquing cone pats.  Just put them in the clay pat and then use an old cone to poke lots of holes in the clay, so it can dry out without exploding.

 

Also, if you're bisquing them with the cones in place, you will reduce the accuracy of the cones, since they have already had a fair amount of heat work.

 

It's been decades since I had a cone pat blow up.  But to be honest, I glaze, load, and fire on the same day, and a just-glazed pot has enough water in it to be troublesome.  So I always pre-heat my glaze firings, and I'm sure that makes it less likely that the cone pat will explode.

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The clay supplier I frequent recommends stippling the surface of the cone pack base with a needle tool and microwaving them to drive off the moisture.  I've never tried it, the idea scares me a little, but she swears by it.  

 

This came about after she was out of the premade cone holders, which is what I prefer--one less thing to prepare for a firing.

Tyler;

Make a note to not ever go to her place for dinner,esp. if she is micro-waving.Is that a verb?

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Never bisques one in 40 some years-I pre make them -6-8 of them at a time out of porcelain scrap and dry them on the heater with a pilot flame going so they are always dry.If I'm in a hurry and out of dry ones I wedge vermiculite and poke holes

in they but 99.9 do not get this treatment. I always plan ahead and they are dry.

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To answer the other question.... Will bisque firing a cone 5-6-7 pack change the properties of the cones?

 

I cannot fully guarantee the answer but I would say No.

The reason is complex or overly simple. The relatively low temperatures of ~1000°C are not high enough to start changing the ∆5. Holding the ∆5 at 1000°C for 100 hours will not cause it to bend [not tested].

 

I guess the simple analogy would be: if you push on a giant rock did you do any (physics definition) work? You might exhaust yourself but no work was done.

 

 

I have reused cone packs for misfires and they seemed to act normally. I haven't put fresh cones next to them to compare though.

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I never bisque them, but have had a few blow over the years, not so much anymore. When I make mine, I usually make about 3-4 at once with a long coil. I place the cones in the coil leaning perpendicular to the length of the coil, that way I can see each one as it drops through my little peephole(L&L with no controller). After setting the cones, I use a pencil or a sharpened round rib to perforate the clay multiple times. Then I cut the lengths with a metal rib, and perforate the ends also. I let them dry til firing time and then do a light (1 hr) water smoking to drive out atmospheric moisture. I also do this in the glaze load to dry the pots if freshly glazed, relieves shivering and other defects. I do use the 5,6,7 line up, and it has been very consistent for me over the years. I have also gotten pretty good at color temp recognition for my kiln and use that to help me judge how long before cones will begin to drop, experience will often make up for lack of intelligence. :rolleyes:

 

best,

pres

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I fall into the category of making several at one time and allowing them to dry thoroughly. There is a previous post on this that includes suggestions and images: http://community.ceramicartsdaily.org/topic/6923-making-cone-packs/

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I would never personally bisque cone packs.  My theory is that when you re-fire ceramics the "maturation temp" so to speak goes down a little each time you re-fire.  So if ^04 was originally at 1941* the first time, it might be 1925* the second time, etc.  I'd never want to compromise the device that is measuring the maturation temp in the kiln, so I'll never bisque cone packs.

 

The standard is to either make cone packs in advance so they are bone dry, or to perforate the clay with hundreds of pin holes to allow steam to escape quickly.  In our studio we simply use kiln putty/kiln wadding to embed our cones in, instead of regular clay.  It's the same material we use between bricks and shelves in our stack, since our biggest two kilns are a shuttle and a trackless, with literally tons of weight on them and plenty of vibrations - the wadding helps dampen vibrations and also level shelves against bricks.  I've stuck freshly made cone packs and kiln gods and small wadding sculptures directly into all types of firings and have never seen it crack, split, blow up, etc.  It's an expensive material since it's a consumable that's only used for firing.

 

Kiln wadding recipe:

1 Silica

1 EPK/Clay

1 Grog

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I buy the stands at $1.25 each. Put kiln wash on them and they last. The only ones that I have had any problems when I did not use kiln wash, the cones bonded to the holders. I will add some kiln wash to them maybe every 30 firings .

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I do as Mark C. describes, mostly, for my ^10 pads, wedging in vermiculite (still have a huge bag of it saved from when cones came packed in it) AND poke holes AND fire a batch of them in a bisque. No bother to fire them, they can even be tumbled in a bowl or lined up on a plate.

 

Although the cones MAY vitrify some (apparently possible), because they are all pre-fired they all produce the same "readings".

 

A friend, who had never used a microwave (this was the 80's), forgot his cone pads when he was firing at my house. He decided to rush-dry his solid clay pads in my microwave. He put them in wet, turned it on for 10 minutes (!!!) and walked away. He didn't get very far before the explosion occurred. It even blew up the glass tray!

 

I have used my microwave to emergency-dry cone pads made with vermiculite and poked with holes. The important thing to remember is that the clay will heat up from the inside, so 10-15 seconds at a time, with a cooling/steaming-off period between heatings, works pretty well.

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I buy the stands at $1.25 each. Put kiln wash on them and they last. The only ones that I have had any problems when I did not use kiln wash, the cones bonded to the holders. I will add some kiln wash to them maybe every 30 firings .

That is a really good idea!

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