How much vermiculite

[Jeffd]

Hi would anyone know how many litres of vermiculite one would need when building a 39inch WFO.Intend putting 100mm in Hearth and 100mm in dome. This would be based on 6:1 for hearth and 12:1for dome

[david s]

Re: How much vermiculite

V ( sphere) = 4/3 phi rxrxr. Calculate outer radius minus inner radius and remember it's half a sphere.
V ( slab) = lxbxh

About 400 L at a rough guess.

I use 10:1 over the dome, I find 12: 1 a bit hard to make it stick on the vertical. Once it starts to lean in you can make the brew weaker.