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Bisque firing ,bungs in and out when.


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The big kiln at the centre only has one bung.  As it fires over the weekend ( I set it up on Wednesdays - at least I did, until covid), I'm not there to play with bungs.

Same with my own little kiln, side bung is in, top bung is out.  As it goes on overnight with Economy 7 cheap rate electricity the bungs stay put.  Can't be messing.

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On 11/11/2020 at 3:47 AM, Babs said:

Just asking because .

Whe  bisquing I have all bunbgs out till 700degC then put all in except one on lid, top loader electric.

Done this for years, still solid logic?

No vent

 

Still good. But you could just leave the top out and not mess with the others if you don't want to.

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21 minutes ago, Magnolia Mud Research said:

If the clay body requires any combustion, logic seems to prefer having separate incoming and outgoing openings for the  gases.  At least that’s what my physics and  engineering schools recommended.

Since air is so thin when it's past say 1000 degrees, is there really much convection happening?  I have a feeling a kiln with a vent is 1000 times more efficient since there's no draft in an electric kiln.  Is that right? Or is the gas exchange not really that significant in an electric kiln.  I've never had carbon coring or anything in an electric kiln, regardless of peep arrangement.

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3 hours ago, liambesaw said:

Since air is so thin when it's past say 1000 degrees

I would agree, the atmosphere is so thin at high temperature  we never feel  or observe anything push out a spy hole  when we remove a port plug. That said leaving a plug or two out seems to have very little negative effect on firing time as well. A power vent is definitely more effective and a properly operating one removes an extremely  small amount of kiln air per minute when we  actually measure it.

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1 hour ago, Bill Kielb said:

That said leaving a plug or two out seems to have very little negative effect on firing time as well.

In a bisque it won't really matter. But in going to cone 6, leaving too many peeps out will affect the firing time, or even prevent the kiln from reaching temp. About once a year I get called to fix a kiln that ins't broken, they're just leaving all the peeps open because they broke all the plugs.

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I have always had a tendency to leave top two plugs out, when bisquing. The glaze load gets the top two out until 1200F. , Then I put them in. I have had problems in the past with poor color and found that the plugs out helped get crisper brighter colors. Firing down slightly also gave me a little more depth and crystallization.  Some of this may have been because of waxing bottoms.

 

best,

Pres

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1 hour ago, Pres said:

have always had a tendency to leave top two plugs out, when bisquing

Sounds logical and likely has little effect on firing time. Not a whole bunch of air moves around after red heat but I suspect small amounts are just what the doctor ordered. Time tested! Wax is always difficult through about 800 degrees even with a downdraft vent.

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@Pres  I actually do (read your stuff) and you are probably the last person I can think of that fires by color which is impressive . It was an extremely important skill  in early use of kilns. Humans can actually do some amazing things. Damage to eyesight was an occupational hazard. I like electronics a whole bunch but most often we struggle to emulate human skills with what seems like electronic precision. Controllers likely good for most folks though but the lessons of heat color sort of lost in textual explanations likely never to be learned with appropriate appreciation.

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Eye sight is still good, but my tendency to fall asleep, or miss an alarm is becoming more possible. Watching a kiln constantly is tedious and exhausting. I have pretty well timed firing length to make things easier, but then replacing elements, varied packings and changes in my electric from the city are factors that make constant monitoring necessary. We all deal with it so pot on!

 

best,

Pres

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On 11/13/2020 at 7:55 AM, Pres said:

@Bill Kielb, you may not realize that I fire without any controllers or setters. My L&L was ordered without them in the 80's. I have fired almost entirely with heat color and cone packs. However, am considering a controller to make life easier as I get older.

 

best,

Pres

Seat of your pants firing Pres-its what many of us old timers  do. I fire all bisque without cones in gas kilns.Color is key.

One needs to know what the real process is and not take for granted all the time modern convinces .

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