Kiln lid propped

[Coco]

I have just now read it's not necessary to prop lid of kiln during the first 1000 degrees. Great news! But here's my question...what happens if the lid stays open through the whole firing and doesn't get closed until it's cooled back down to 1000 degrees? 

 

[Bill Kielb]

Sort of like leaving your window open a bit in the winter. The kiln will leak energy faster, the firing will require more energy and the kiln will cool more quickly at the end of firing. Providing of course the firing makes it to the scheduled off temperature.

Most automatic controllers will stop on error if they cannot heat at a certain minimum speed. Just like leaving that window open a bit, if your furnace is large enough it just runs longer or more often. If you open three windows, it probably will not keep up and your house will cool.

why are you propping it open to begin with? Maybe to keep the heating rate slow until moisture and burned out hydrocarbons are released slowly?

[Coco]

Because I don't have a vent, Skutt suggested I keep lid propped for the first 1000 degrees. I've only had my kiln for a few months.

Thanks for the reply.  Makes perfect sense.

[neilestrick]

There's really no need to prop the lid. Just keep the top spy hole open. Propping the lid just wastes heat, makes your elements work harder, and can cause digital controllers to error.

[Coco]

Good to know.  I'll skip the lid propping next time.