Brick Dome

[trenchn]

Hi All,
I am working on my first proper oven. the first one I built burnt well, but wasn't well insulated enough. mark two is bigger, better and being built almost entirely from reclaimed materials.
It has an internal diameter of 900mm. I have built the base and cut a fire brick floor to fit inside the circular walls. (Firebricks from old night storeage heaters). I am struggling to find a way to build the dome that I am capable of doing. i have two ideas.
1. form a dome shape in pliable wire and then build over it.
2. Step in each course of bricks by about a third of a bricks width so that it gradually goes in and will eventually meet. I could smooth over the "steps" with mortar if it is necessary.
What do you experts think?
Look forward to hearing from you.
Cheers
Nick. (Badsey, England.)

[dmun]

Having a smooth interior curve in actual firebrick material is worth the trouble, because the heat of the fire is reflected down from the fire, and radiated out from the hot bricks. We do this by tilting up each layer, or course, of bricks slightly, like 5/16 of an inch(8mm), on the outside. Experience shows that it's better to have excess mortar at the outside of the curve than on the inside where it runs the risk of chipping off from thermal shock and landing in your pizza.

Also, your "step" plan puts the biggest steps on the top of the dome where the temperatures are the highest.

[trenchn]

OK, I'll give it a shot.
Thanks for your advice.