Is that duct tape?
Are you going to close up the back of the oven?
Yes. That is duct tape.
It was put there to hold the six layers of Aluminium foil I wrapped around the steel barrel in place. Because I was doing this Woof Fired Oven in my spare time I had to hold it in place with something.
I figured because it would have no contact with the inside of the oven and it was going to be covered with a mixture comprising the following.
and Hydrated Lime
for the insulation and then a mixture comprising just Clay, Sand and hydrated lime with Yellow oxide I bought cheap for some of the top coats.
I have had to do about six layers.
The back was filled in with some solid red clay pavers that I had cut and shaped similar to the front so I had a neat fit inside the steel drum inner circle.
The mortar I used for all the brickwork and the base below the fire bricks in the barrel was a mixture of Clay, sand and hydrated lime. The next photo will show the rear of the oven filled in with the clay bricks.
The reason I used them was because I am cheap and had them lying around otherwise I would have had to use expensive fire bricks. My research indicated that a lot of people just used clay pavers for the oven but I went with the fire brick floor laid on a metal screen and levelled out with a mixture of Clay, sand and hydrated lime.
The back of the clay bricks was covered with some Hebel A.A.C. concrete blocks that went up to the level of the side level. As the oven sat on a floor of Aluminium foil plus Hebel blocks and then the 3 inch hardwood I figure with luck that might be sufficient insulation.
The gap at the bottom of the drum and the sides of the Hebel blocks was filled wit a Clay, sand and hydrated lime mortar mix for extra mass.
This was not a commercial oven and I was basing the build on something I had read plus my own interpretation of the adjustments I could make based on my ability and materials at my disposal.
The more insulation and mass the longer the oven will take to reach critical heat and the longer it will hold that heat. It then becomes a trade off, the quicker the heat, the quickerr the loss when the heat source is removed. That was the unknown to me, but at this stage I think it looks like it will take about three hours to reach critical mass heat and hold that heat for a few hours then start to drop slowly.
That is where my new thermometer will help. If I have to put more mass into the build it can easily be done, but being time poor, I have already mentioned money poor, I may go with what I have got. It is not like the oven will be used every day ,be lucky if it is just once a month.
I built it mainly for show and to fit in with our outdoor entertainment area that I am working on at the moment.
Thanks for your interest and comments.