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Tonyp 01-15-2009 10:14 AM

Local firebrick choice ok?
Hi All,

Looking to build my indoor WFO with firebrick interior. The local Taylor concrete here has Heatstop50 yay. But I am not sure about their firebrick. It is from Whitacre Greer and according to the product data sheets is 27.6% Al2O3 63.5% SiO2. From my research I was under the impression I should be looking for 30-35% Al content? Should I look for another source of firebrick with a higher Al %? Here is a link to the manufacturer data sheet



Tonyp 01-16-2009 12:28 PM

Re: Local firebrick choice ok?
I should add that I like both pizza and roasting/backing maybe 50/50. So I am looking for a wfo that will hold a good amount of heat but not be overly difficult to reach pizza temperatures. I am not opposed to taking a bit longer to heat for pizza as long as the oven will also have good residual heat storage for bread, roasts etc a day or two later.

Will this brick with only 27% Al heat up too slow or not hold enough heat for later use? I was also contemplating refractory mortar cladding around the dome to bring the total thickness to 6". The Bread Builders book mentions the hearth should be 1" thicker. Which would put my brick and refractory hearth at 7" combined.


glennb 01-17-2009 01:33 PM

Re: Local firebrick choice ok?
my understanding (others will correct me if i'm wrong), is that the Al content in the brick reflects on their duty type (light, medium, heavy) which is to do with the temperature that they are rated for (max).

As these are refractory bricks, the 26% Al would be light duty, rated to something like 1200 degrees C, which is about 3 times higher than you will every reach in an WFO.

It "shouldn't" make much difference to the heatup and heat retention times (i'm going from what i've read rather than experience here).

I started off my thinking similar to you in terms of wanting to use the WFO for as much baking as for pizza and was thinking about adding thickness, but from other users, they have been able to bake breads etc perfectly well without adding wall thickness. It all comes down to the effectiveness of your insulation i think.

wlively 01-17-2009 04:29 PM

Re: Local firebrick choice ok?
Your local brick is fine, no worries.

Unless you plan to bake many many loaves of bread over a full day there is no reason to add claddding to get a 6" dome thickness. A very well insulated oven built per plans will bake more bread than your household can eat. So, if you want to go the extra mile use it on insulation and not thickness. You will not have to extra fire your oven and the heat you charge the bricks with will have only one place to go and that is into your baking.:)

Tonyp 01-18-2009 03:19 PM

Re: Local firebrick choice ok?
Thanks for the comments. I was planning on using 3" of the ceramic blanket insulation. I am unsure yet how I will finish the outside and if there will be space for some loose fill. There is certainly room to add more blankets around the majority of the dome. Only right at the first soldier brick course does it become a space issue with the outer dimensions and the kitchen walls and counters. I will continue to read up on dome thickness and probably not reach a decision until the day comes when it's either insulate or add more refractory!

Does anyone know if a study has been done to determine how much time it takes a firebrick dome WFO reach the proper temperature vs the same type oven with 1" or 2" of additional cladding?

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