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Firing Light Loads ?

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When you must fire a less dense load than you usually do, due to some 'gotta have it' situation, do you change your temps or holds to compensate?  Last time I did a bisque that way the cones were over fired,even with extra shelves and posts to make more mass  but the glazing process did not seems to differ.  What about a light glaze load?

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I usually remove one section of my kiln for light loads. This way the density of the pack is closer to being 3 sections. When i have a really tight load, or not enough space I add a fourth section. If you have sectional options learn to use them to adjust your kiln pack. :lol:

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When I have to fire a light load I've noticed that generally the firing takes longer than usual. I haven't noticed a huge difference in the cones though. I wonder how much of this has to do with your controller. Are you using a Bartlett controller? Or manual? Or?

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Really Tristan?

 

My classroom kiln, fires much faster with a light load.  Towards the end of this past term, I had four packed layers, and firing would take 6 to 7 hours for a glaze fire (low fire).

 

When I do three layers, moderately packed, a glaze firing can take just under five hours.  

 

Of course the difference in temperature between low to mid and high fire, may make a difference.  I haven't done enough of those firings to be able to know for sure.

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Really Tristan?

 

My classroom kiln, fires much faster with a light load.  Towards the end of this past term, I had four packed layers, and firing would take 6 to 7 hours for a glaze fire (low fire).

 

When I do three layers, moderately packed, a glaze firing can take just under five hours.  

 

Of course the difference in temperature between low to mid and high fire, may make a difference.  I haven't done enough of those firings to be able to know for sure.

 

The only explanation that I can think of is that when the load is really light that the heat transfer is less efficient ( I fire to cone 7 ), but yeah.., it consistently takes longer with a very light load than it does with my usual dense load.

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Really Tristan?

 

My classroom kiln, fires much faster with a light load.  Towards the end of this past term, I had four packed layers, and firing would take 6 to 7 hours for a glaze fire (low fire).

 

When I do three layers, moderately packed, a glaze firing can take just under five hours.  

 

Of course the difference in temperature between low to mid and high fire, may make a difference.  I haven't done enough of those firings to be able to know for sure.

 

The only explanation that I can think of is that when the load is really light that the heat transfer is less efficient ( I fire to cone 7 ), but yeah.., it consistently takes longer with a very light load than it does with my usual dense load.

 

 

 

Yep, that's what I'm thinking too.  I'd say the only reason it's faster with low fire, is because the kiln gets up to that temperature fast, but wouldn't be able to for mid to high fire.  Those last couple hundred degrees make a big difference for clay, glaze, and apparently the heating devices as well.

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The only time I fire a light load is for bisquing in my own studio. I put six in ch props, then the shelves and stack bisque as per usual. i would never fire a glaze kiln that was not tightly packed, as I am firing to cone 10, and would not want to be profligate with the space.

TJR.

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Faster cooling may be an issue in the cooler areas of the world.

I'm thinking faster on the beginning stages and then poss slower towards the top of the firing schedule. Is this logical thinking, the mass of pots would hold /radiate heat better than air???

Don't do it personally as a waste of energy etc.

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