Oven Insulation

[palmtrees126]

I just completed insulating my oven, but I'm so sure I did it correctly. I mixed 10 parts of vermiculite to 1 part portland cement and 3 parts of water. I also place three layers of heavy duty aluminum foil over the bricks and then proceeded to put wire mesh over the foil then the insulation. From what I see of some of the mixture that fell on the ground and dryed it's very loose and I'm afraid when I take the forms away it will crumble. did I do it right? will it crumble should I stucco it? Help!

[david s]

It should harden up sufficiently for you to stucco over it.

[palmtrees126]

hi David,
how long do I need to wait before I can remove the forms around it

[david s]

I don't use forms, but rather just press the mixture in place and tap the outer surface with the flat of a trowel. If you've used formwork I hope you oiled the face of the forms, otherwise I think it will stick. 24 Hrs should be sufficient for it to harden enough. Making the mixture stronger by adding more cement is a mistake in that you reduce the insulation efficiency. You want it just strong enough to stand up on its own and be firm enough to take the stucco coat. A 10:1 mix seems about right.

[palmtrees126]

Thanks David for the quick response. I didn't oil the form.
I built a barrel type oven. I may use stucco or I might just
Brick the walls and put a roof over it