Using Aluminum Foil

[durangout]

Has anyone given any thought to using aluminum foil as the first layer of insulation? What I mean is under the floor fire bricks and covering the dome before the ceramic blanket / vermiculite.

It seems like this would be a very simple and cheap way to improve thermal retention.

[meco211]

I am going to use foil oven the dome of my oven before i cover it with a couple inches of concrete. Then put the layer of insulation mix.

[david s]

I tried foil over my dome after the insulation layer and would not do it again. It provides a moisture barrier which holds the moisture in. Extremely hard to get the oven fully cured and also a pain after heavy downpours when the oven will inevitably get moisture in it even though it may be waterproof on the outside. If the outside humidity is 10% then your porous inner layer must also be getting its fair share of moisture. I know it is the foil layer holding in the moisture because I poked lots of little holes through the foil in two places. Guess what ? that is exactly where it gets hot on the outside while the rest is only warm, indicating steam finding its way through the holes.

[david s]

A foil layer over the dome, then another layer of concrete over that will not insulate because it is in direct contact with both materials All it does is stop moisture from the concrete leaching into your dome bricks or inner refractory layer. This would seem sensible to keep the concrete layer wet for increased strength, but it will still prevent moisture movement between the layers later which is a disadvantage. Some folk also report that foil breaks down with heat. This topic has come up before. Try a search for previous threads.
Dave

[jota112233]

Was thinking of using foil myself, as it's recommended in Alan Scott's book "the bread Builders". Albeit thats for a barrel oven.

Having now read this post, I won't be. Thanks for clearing that matter up...

Regards

Jon
Cardiff

[dmun]

The consensus seems to be that foil is pretty much useless. Save the step.

[durangout]

Thanks for the "tribal knowledge" out there. It sounds like you guys have saved me some heartache.

[david s]

I just read my previous post and realized I said 10% humidity. Of course I meant 100% Sory if that led to confusion.
Dave