Powdered Fire Clay

[sidamo]

How many lbs of fire clay do you guys estimate i'd need for a 36" build ~using 3 sand to 1 clay ratio. I am in the planning stages and digging clay isn't a good option for me. Thanks!

[Mooveebuff]

Re: Powdered Fire Clay

I had the same problem...digging for clay here is almost impossible, so I went with Muddox powdered fire clay on my build. If I remember correctly, I went through seven 50-pound bags for my build. I did, however, go through a lot of it when I made the insulating pad under my oven's floor. I probably went through two bags right there to make clay slip to mix with perlite. On the outside of the dome, I used Portland cement mixed with perlite and vermiculite (the Portland cement was much cheaper). On a guess, I would say I used between 4-5 bags of powdered fire clay to build my dome. My dome is about 36" deep by 27" wide. The thickness of my dome is horribly inconsistent (I tried to keep it about 4" thick but it's thicker in spots), so you might be able to get away with using a bit less if you're more careful about it than I was. I used a 3 part sand to one part clay for my dome as well, so I'm guessing you'd be using about the same give or take. Hope that helps!

Here's a link to my build if it helps you at all. On the first page is a picture of the powdered fire clay I used, about halfway down the page:

http://www.fornobravo.com/forum/f43/...ild-18673.html

[Tscarborough]

Re: Powdered Fire Clay

Fire clay and sand is not a mortar you know. It is simply chinking material, it has no adhesive or hydraulic properties at all.

[cobblerdave]

Re: Powdered Fire Clay

How many lbs of fire clay do you guys estimate i'd need for a 36" build ~using 3 sand to 1 clay ratio. I am in the planning stages and digging clay isn't a good option for me. Thanks!

G'day
Just to clarify ..... You are talking about a cob oven aren't you?
Regards dave

[Mooveebuff]

Re: Powdered Fire Clay

I think he's talking about a cob type oven...that's what I was assuming...I built my whole dome out of a 3:1 sand to fire clay mixture.

[cobblerdave]

Re: Powdered Fire Clay

I think he's talking about a cob type oven...that's what I was assuming...I built my whole dome out of a 3:1 sand to fire clay mixture.

G'day
Yes the fireclay confused me a bit ,more common to use it the home brew mortar.
It would make an expensive hard to procure product around these parts. Easier to get hold of a powdered clay. At the temperatures a WFO operates the high temp properties of fireclay is a bit wasted.
Still in saying that if it works it works. And a lot easier that mining it youself and crushing it. I would like to spend my time on the build personally.
By the way how's your oven doing.
Regards dave