Homebrew Cast Oven Help

[watchthenanacrossing]

I can't believe the amount of help from everyone in these forums! Rock stars.

[watchthenanacrossing]

So I contacted Knauf and they are out of stock of any calsil, but they do have perlite blocks. Here's the specs:

https://tps-industrial-insulations.c...Sheet-7-20.pdf

Seems like this would work just as well as calsil, and it's a lot more affordable.

[Gulf]

The compression strength is just fine (note Russell's UtahBeehiver advice in post #11 ). I don't know about the thermal conductivity of that particular product. But, it takes abaot 4" of v or pcrete @ a 5 to 1 ratio to equal the effectveness of 2" of CalSil.

[watchthenanacrossing]

I was told the thermal conductivity equals and maybe is better than calsil. I'm gonna go ahead and use this instead of calsil since I'm in a time crunch to get the oven casted before cold weather moves in.

[watchthenanacrossing]

So I've begun gathering the materials to begin casting the dome hopefully next weekend. Here's the quantity I've come up with based on other's that they've used, so I want to check and make sure it seems right. This is for a dome that will be 16" in height, 30" cooking floor, and a vent landing (and door opening) that's 18" W x 11" height x 9" deep:

For the dome:
2 X 60 LBS Cement
1 X 50 LB Hydrated Lime
1 X 50 LB Fireclay (already have bags of it in my garage)
Sand - I have a pile of sand on my property so I don't have to worry about purchasing a set amount
6 LBS Stainless steel 1" refractory reinforcing needles
2 LBS Polypropylene reinforcing fibers

For the insulation layers around dome:
8 cu. ft. vermiculite (sold in bags of 4 cu. ft.)
2 X 60 LBS Cement (this seems low)
24 ft. of ceramic blanket

Sound right? I have to order some materials so I want to make sure I have enough instead of waiting around more if I need to reorder.

I am also going to cast an arch because I came across this post and like the look of it. Looks like he just used all concrete to make the arch unless I missed something. Is that okay? Does it need to be a mix of refractory to handle heat coming out of the oven?

[Gulf]

I can't help you much on casting. david s is the forum expert on cast ovens. But, Nick J C and his 32" oven build that you linked above should be able to give you a very close idea of the amount of material needed for your build. However, I would like to ask you about the "2 X 60 LBS Cement". The most common bag size for portland "cement" is 94 lbs. 60 lbs is a very common size for bagged "concrete". Searching one term on the net will bring up both, but there is a critical difference. Portland cement is just that, portland cement. Concrete is portland cement with the sand and aggreagate added. You probably know the difference already but, I have learned on this forum not to assume too much!

[watchthenanacrossing]

Yea, I am familiar with the difference. I just assumed they were sold in the same size bags.