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Re: Mortar Mixes
It's not the cracking/flaking I'm worried about (in OP mixes) tbh - it's the refractory properties.
I'm cutting my bricks with a bolster; they will not be angled in any satisfactory way. There will be (a lot) of mortar between joints. I may use a grinding disk to remove some sharp angles, but the way I figure the bricks are cut in half - the "smooth" edges (i.e. the non-cut face) goes inside the oven and the cut face is buried under layers of insulation... so I'll have triangles inside... but I'm not too concerned...
Based on the pdf I posted before, by changing the mix of chamotte (more coarse chamotte for thicker joints) you can fill some pretty thick joints... I'm ordering chamotte all the way to the 6mm grain size, so shouldn't have an issue filling my triangles.
The larger gaps will essentially be a castable refractory mix - coarse+medium+fine crushed firebrick grog, fireclay and HAC. Total alumina content will be proportional to the ingredients, so between 36% and 42% (if I use cheap HAC - if I were to go all out, kerneos do some with 80% alumina... but that's harder to source - and more expensive)
Dome will be built in a day... that's the plan! (and though I am Italian, I'm doing it for time reasons, not because I thought that's what was needed!)
1st layer of floor insulation has finished curing, and is now drying - 4" of vermicrete. Once it's dry, it will get 4" of bio-board (like ceramic board, but with a higher temp rating and not carcinogenic).
TBH - I just don't see the value of homebrew bar its "ease of use".
It's not substantially cheaper (using UK suppliers) and has negligible refractory properties. Even the ease of use is contestable, as I need to get the entire dome built in a day... so the curing speed of HAC will be beneficial (planning on getting a helper to mix while I mortar - one "ring" at a time using a foam/wood form for the last rings).
M.
It's not the cracking/flaking I'm worried about (in OP mixes) tbh - it's the refractory properties.
I'm cutting my bricks with a bolster; they will not be angled in any satisfactory way. There will be (a lot) of mortar between joints. I may use a grinding disk to remove some sharp angles, but the way I figure the bricks are cut in half - the "smooth" edges (i.e. the non-cut face) goes inside the oven and the cut face is buried under layers of insulation... so I'll have triangles inside... but I'm not too concerned...
Based on the pdf I posted before, by changing the mix of chamotte (more coarse chamotte for thicker joints) you can fill some pretty thick joints... I'm ordering chamotte all the way to the 6mm grain size, so shouldn't have an issue filling my triangles.
The larger gaps will essentially be a castable refractory mix - coarse+medium+fine crushed firebrick grog, fireclay and HAC. Total alumina content will be proportional to the ingredients, so between 36% and 42% (if I use cheap HAC - if I were to go all out, kerneos do some with 80% alumina... but that's harder to source - and more expensive)
Dome will be built in a day... that's the plan! (and though I am Italian, I'm doing it for time reasons, not because I thought that's what was needed!)
1st layer of floor insulation has finished curing, and is now drying - 4" of vermicrete. Once it's dry, it will get 4" of bio-board (like ceramic board, but with a higher temp rating and not carcinogenic).
TBH - I just don't see the value of homebrew bar its "ease of use".
It's not substantially cheaper (using UK suppliers) and has negligible refractory properties. Even the ease of use is contestable, as I need to get the entire dome built in a day... so the curing speed of HAC will be beneficial (planning on getting a helper to mix while I mortar - one "ring" at a time using a foam/wood form for the last rings).
M.
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