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Has anyone built an oven with firebrick splits instead of regular fire bricks? I figured it would create smaller mortar joints. If you cant find SuperIsol will any type of Calcium Silicate board work?
Boy - having built my dome with 1/2 bricks, I kind of hate the idea of using splits - maybe thinner mortar but more bricks to handle. I just groan at the idea that it might take any longer than what I used. If you did this, use a premium refractory mortar like refmix - it should handle much better than the recipe I used with lime, sand, fireclay and portland and you could justify the cost better with the plan for smaller seams.
Sure, splits would work great, they are even easier to cut than regular sized bricks. Some of the ancient pompeii ovens shown on the FB site were made from thin tile like elements. The problem: they cost the same as full sized bricks, and you would need twice as many of them. That brings them to the cost level of tapered refractorys, where you can get a true close-fit oven.
Not only will any kind of cal-sil insulating board work, but other kinds will work as well. I used harbison-walker insblock19, a fiber wool product. It was mostly a cost decision.
I have seen ovens where they used normal bricks for most of the oven dome...probably first six courses and then used splits for the remaining courses near the top. The splits weigh less and therefore are easier to keep up on some of the more vertical rings near the top...as well as the fact that they are easier to cut.
"Making the simple complicated is commonplace; making the complicated simple, awesomely simple, that's creativity. " Charles Mingus
"Build at least two brick ovens...one to make all the mistakes on and the other to be just like you dreamed of!" Dutch
I think you need refractory mortar, portland cement will fall into your pizza. I used Refmix from Forno Bravo, very easy to use but expensive. Or you can make your own from calcium aluminate cement. Trade name Lumnite.Cheap but very difficult to use, it is stiff & goes off very fast.
The formula I was given differs from that in the Forno Bravo plans so you should check it out farther, the one I've used is 2 parts Lumnite, 2 parts sand, 1 part fireclay.
I know some of the other guys used Heatstop but I don't know anything about it perhaps they can help.
Personally I recommend Refmix if it's in the budget.
do i need to use refractory cement or can i use a reg portland / limes type s mortar ? thank you
Don't use type s mortar mix. It breaks down with heat, and causes your dome to crack. Better is the fireclay/sand/portland mix, best is a dry pre-mix mortar like heat-stop that's matched to the expansion of your firebricks.