Hi Sarah,
The first layer of insulation is a double layer of 2" rockwool with a silvery backing - mainly because that was all I could find. Then I coverd it with a layer of loose vermiculite, because the rockwool should not be compressed...
I'm a bit puzzled about the insulation properties of my oven at the moment though: I cooked 11 pizzas over lunch today and had a ball. I have no problem getting the heat up and each one cooks in about a minute. I'm astounded at how well it all works and how good they taste...
But the bread I baked this afternoon didn't brown on the bottom properly. Well, I did some yesterday leaving the coals in the oven and it got a bit too brown - so I took the coals out today. And by this evening the oven isn't really hot enough to cook in. I don't know, is the heat leaking out the oven floor? Is the rockwool not a good enough insulator? Should I keep the big fire going for longer if I want to cook again in the evening?
On the other hand the oven was warm inside two days after firing... I dunno. Maybe I just shouldn't compare my oven with Dave's
. After all, I am cooking some great meals in there...
Any tips anyone?