Waterproofing the blanket

[talisker63]

I have been told that i should add a waterproof layer over my insulating blanket before applying any pearlite/cement insularing layer. This is to protect the blanket from getting wet during the application of the pearlite/cement.

The issue I have it that I was told to use a plastic sheet, wouldn't this melt

Other research on a great WFO site in Australia (Rado Hand) suggested using aluminium foil (alfoil?)

I have applied the foil and have the chicken wire in place, ready for the pearlite/cement layer this weekend.

Shoud I continue?
Backout and replace with plastic sheet?

any advise welcome (as always)

cheers

[Mojoe]

Re: Waterproofing the blanket

I don't think the foil would create any problems, not sure how waterproof it would be along the seams. Some brands of insulating blanket however, fully recover from being wet after drying without losing any properties (Inswool for one). As far as questioning Rado's knowledge, I bought his cd to fill in the gray areas in Alan Scott's book and I feel he has very sound construction principles.

[Frances]

Re: Waterproofing the blanket

I thought I read somewhere here that the protecting layer shouldn't be entirely waterproof, so that steam and water can continue to work its way out of the dome.. bit of a catch 22 thing really.

But just from the feel of the thing I'd go with the foil, because a) you've already put it on there and b) ...plastic inside the dome construction?

[talisker63]

Re: Waterproofing the blanket

Thanks, as there are some inevitable holes in the foil - steam can escape...

Best of both worlds maybe.

cheers

[Frances]

Re: Waterproofing the blanket

You know, that's pretty much how mine turned out...

[arevalo53anos]

Re: Waterproofing the blanket

Talisker63

The aluminium foil in Rado (and others) oven is just to permit free movement between the different layers with different thermal expansion ratios, like the refractory bricks and the cladding.
You would not like any foil over your blanket, just chicken wire to fix the cladding.
The secret in structures with big temperature variation is to maintain the characteristics of each layer as closed as possible from the adjacents ones.
So, the blanket over/under the vermiculite isolation is going to work not only as more isolation as separation between layers.
There will be not a problem that the blanket be wet, you just will need to fire your oven from small to higher fires, how was explained around this forum.

Luis

[arevalo53anos]

Re: Waterproofing the blanket

Sorry, re reading the post above, I need to add that the aluminium foil will maintain the humidity inner the oven structure, closing the path of the hot gases to the external next layer (that may be the cladding, depending on your construction).
The only place where could be good to put aluminium foil is over the vermiculite, or under the roof, just to wheather protection.

Luis

[talisker63]

Re: Waterproofing the blanket

Hmmm.

So as long as I supidly punch a few holes in the foil - all should be well

thanks for the input