q's about firing in a somewhat empty kiln

[dAO]

Hi Collective Minds.  I am a new-ish hobby handbuilder.  If I waited to fire my work (both bisque and glazed) until my electric kiln was full, I'd only see finished pieces about once a year : )    What do I need to  know about firing a few pieces at a time in a mostly empty or perhaps half full kiln?  Thank you for any insights and tips

[Bill Kielb]

It can fire faster and likely will cool faster. There is no rule that says you need to overfill a kiln, that is more of a studio thing to maximize the throughput of the resource and maybe save a little electricity since you will only pay once  for the thermal losses through the kiln walls.

notice I said can, meaning for firing if you use an automatic controller the kiln  will likely take the same amount of time to heat up as this will be driven by schedule. Cooling quicker is  likely because you will have less stored heat.

The cooling could change your glaze look somewhat a bit if your glazes are sensitive to the new rate.

In our test kiln which fast glazes in just under five hours and cools to 200  degrees or less in 14 hours, I notice slightly glossier mattes.  That’s about it, most of my glazes perform near the same. Of course since the kiln has a programmable cool ramp that can be added for all firings I could make it match the bigger kilns if I wanted.

Its just a test kiln for small items and test tiles, I rather get my results the next day. There is not enough difference in my mind for these pieces.

An interesting fact, our kilns use the old 1” heavy cordierite shelves. Often the shelves weigh as much as the pots in the kiln. Changing these to lightweight shelves would actually save significant energy and speed up the cool down, same way as you firing a partially filled kiln. Less mass, less energy required, quicker cool down.

[Denice]

If I have a light firing I will add extra  shelves to get a more consistent firing.   I don't have to do this very often I have a test kiln, a  small kiln and a large Skutt.    My small paragon went out last year it was 45 years old.   Thought I could get by without it but I couldn't ended up searching  for another small kiln.  Found a nearly new Blue Diamond at a estate sell.      Denice

[neilestrick]

Just spread out the load so it's somewhat even throughout the kiln.

[LeeU]

My kiln is sometimes too large for me to fill full if something is time sensitive. I've learned to do as Neil suggests--distribute the ware evenly, plus I'll add a few broken shelf pieces, or kiln brick, or even unglazed shards that I use for wasters/cookies. So far, so good, over the last two years of periodically doing these light loads. I have not seen any big difference in my electric bill, either. 

 

[liambesaw]

I put an extra empty shelf on top to help soak up some heat so the top shelf doesn't bake too bad.  If I don't, the top shelf overfires a bit.  This is in a manual kiln so I don't know if the same applies to one with a controller (although I'll find out soon!)

[dAO]

You guys are GREAT!  Thank you so much