More pottery firing with improved kiln: ocarinas, satyrs and udus

[iowabow]

Your fire box and the heat entry is key to high temps. You do not need a bigger fire box just a more efficient one. A fire can only be so hot without some modification to the structure of the fire/ box. The problem comes from poor combustion and the accumulation of charcoal. the larger the fire the more oxygen needed. So a larger fire box will require more oxygen, your kinda now back to the same problem. One solution is to more fully combust the fuel you and not make charcoal. One solution is to introduce air to the bottom of the fire so you will need the fire to be held up so that air/oxygen can move around your fuel. If you create channels under the fire (mouse runs/holes) your oxygen will run under the fire combine with the fuel and enter as heat. There are many variations in forms for this type of kiln engineering. In this post you can see how small the fire box is. The kiln in this post will hit cone 6 in three hours it you let it!
http://www.primitivearcher.com/smf/index.php/topic,24584.15.html
the kiln in this post reached 1950 degrees and was not able to climb any higher because of the fire box construction and volume issues. I still plan on rebuilding it with a better fire box like in the post above but primitive.
http://www.primitivearcher.com/smf/index.php/topic,24584.15.html
As I found out there was a lot of math involved in constructing a good woodfire kiln. The size of the fire box has to work with the volume of the kiln and the chimney need to be the correct size to match the other two. There are really good books on the market that will help you understand the dynamics of the flow in your kiln. interesting point is that at a high temp the unburnt gases then become fuel in your kiln so it is important to make things harmonize. I know it kinda takes the fun out of it but it will also save you many hours of trial and error. My next clay walled kiln will have more design and math for sure. See at around cone 5-6 you can convert ash to a green glaze on the surface of the pot and that is a cool thing. If that is not your goal then having in a kiln that is controlable is helpful so you can oxidize or reduce your pottery. good control of the flow will help with that.

[iowabow]

This a cool effect of ash from the wood as it melts on the pot. I know this is kinda high temp stuff.

[richardzane]

high temp firing is a different topic for sure.
fly ash(flying wood ash dust)  does melt on and make some great surfaces on High temp pottery.
sewer pipe was salt glazed too for years before it was outlawed for creating toxic fumes.

In my own experience with earthen kilns the best intake vent for a fire box (lower temp firing - up to 1800 degrees) is ABOVE the coals.
I've experimented with both and find if air is drawn over the TOP of the coals burns wood cleaner
and prevents any backfiring. If you have a good draw, you should be able to actually sit fairly close to the firing port and not get your knees burnt.

but its always good to experiment and find out what works best for you.
I'm sure some math helps ,but for me its always been about simply doing it and adjusting to make it better.



 

[iowabow]

high temp firing is a different topic for sure.
fly ash(flying wood ash dust)  does melt on and make some great surfaces on High temp pottery.
sewer pipe was salt glazed too for years before it was outlawed for creating toxic fumes.

In my own experience with earthen kilns the best intake vent for a fire box (lower temp firing - up to 1800 degrees) is ABOVE the coals.
I've experimented with both and find if air is drawn over the TOP of the coals burns wood cleaner
and prevents any backfiring. If you have a good draw, you should be able to actually sit fairly close to the firing port and not get your knees burnt.

but its always good to experiment and find out what works best for you.
I'm sure some math helps ,but for me its always been about simply doing it and adjusting to make it better.

totally agree if your not going for high temps keep it simple.

[Jodocus]

Wow, great stuff coming up here 

But I will certainly keep it simple.

[bowtarist]

  I like satyrs. dp