(free!) super duty firebrick for the dome?

[parsley]

I'm trying to build my oven this summer on a REALLY tight budget, and since I work at a university with a big ceramics and art program, this summer I can pick the best used firebrick I can find from a kiln rebuild. Now, this is super duty firebrick, 40-44% alumina, 49-53% silica (I'm putting together information on this stuff at my site). My reading indicates the higher alumina may tend to burn bottom in the hearth; but I'm wondering if there would be any problems using it in the dome?

[Robert Musa]

if its the lightweight, almost pumice like, brick then it will not have sufficient mass to retain heat. you use the brick in the dome for heat storage and not as insulation. the correct brick to use should weigh about 7 pounds.

in my opinion, as long as you stay away from the heavy duty lightweight "foamy" firebricks, almost any other firebrick will work just fine.

one other point, if the firebricks have been used in a kiln you might want to get one of those lead testing kits from home depot and run a test on the bricks.

[parsley]

Heavy bricks

Yes, these are the heavy bricks, close to 7 pounds. They have a dark brown shiny coating; some variety of salt I think. I think I would have to cut them in half with a wet saw, and use the cut face on the interior. The ends and corners may be a bit ragged, but cutting down the middle should give me two nice faces.

[james]

These sound like real firebricks, not the insulating firebricks. One thing to think about is balance between the cooking floor and the dome. You can have a pizza oven that cooks between 900F and 1100F, as long as the dome and floor in tune. The top and bottom of the pizzas cook equally fast. In that sense, there really isn't such a thing as an oven that is too hot. You can have a floor or a dome that is too hot. I think that is where the burned pizza bottom concern comes from.

If your goal is to make a good oven from your "found" bricks, I think you are on the right track. An oven with imperfect basic materials, including either hot bricks or regular clay bricks, is vastly superior to no oven.

I think there is an opportunity for discussion around the material you would use for the floor, if you end up using the hot bricks for the dome.

As Jim once said, it isn't rocket science, and the ovens cook great -- warts and all.

James

[parsley]

I think there is an opportunity for discussion around the material you would use for the floor, if you end up using the hot bricks for the dome.

As Jim once said, it isn't rocket science, and the ovens cook great -- warts and all.
James

Truth be told, I've looked at a couple of commercial brick ovens close to me, and I'm amazed at the quality of pizza that can be gotten from an oven that I consider pretty far from ideal. (it was a brief stint cooking with one such oven that convinced me I should build my own)

As to the floor, the current plan is imperfect hot firebricks in the dome, and purchase low duty firebrick for the floor. If these are 'hotter' brick, maybe I'll just go with the higher dome. My main goal is for the dome bricks not to crack and spall, dropping stuff on my pizzas. If the super duty brick in the dome is most likely going to burn my tops, I'll just save my pennies and go with all low duty firebrick, which I've found locally for $1.20 ea. :-/

While it may be technically possible to later tear down a bad super duty dome, it would take a while to work up the gumption to do so - it looks like building the dome is going to be quite a challenge. I'm the careful sort who normally tries err on the side of caution (except when in conflict with finance).

[james]

They shouldn't crack or spall

You seem to have this well under control. I would add that the basic design is key. If you get the oven layout right, with the floor, dome arch and oven opening working in sync, you will be in good shape. I think that is more important than the specific brick.

My rectangular outdoor bread oven continues to frustrate, and I have finally decided to take it out. It is too bad, and something of a waste of time and energy, but summer is coming its time to get it right.

Have fun -- and send lots of photos.

James

[Yellowbeard]

I know this is an old thread but I have a similar question. I have a bunch of old super duty bricks from a kiln that was actually used to MAKE "regular" red clay bricks. It was a wood fired brick kiln in Kansas and these bricks are close to a century old. I also have some of the "children" from this kiln - clinkers that were fired in it.

My dream is to make a kiln where the firebricks are inside and the clinkers are on the outside. I plan to use something likefor the floor. Can anyone comment on this? I have had one person indicate that the super duty bricks might not heat up and then re-release heat properly for a pizza and bread oven but I would love other opinions.

[fox]

Many folk build their ovens from old clay brick, I like your idea of using the clinker for decoration.
I have never come across the term ‘super duty brick’ modern bricks are often rated to a max temperature rating ie 1700f or 2500f I am not sure exactly what a near 100 year old brick is made from?
Modern Firebrick is made with high levels of alumina and silica whereas old style red shale clay bricks have elevated levels of iron.

The main difference is the rate of thermal transfer through the brick, as firebrick moves the heat through quite rabidly so the temperature on one side of the brick is close to the other side.
The red shale clay brick does not transfer the heat as well and the face side will be hotter than the other side.
All firebricks will expand when heated, if the temperature is uneven the brick will crack as one side expands more than the other. This can occur with each heating or cooling cycle.
You can use red old clay brick but very often they start to powder after a couple of hundred firings that is why they are often replaced in the first place, modern firebrick could last for decades.

Those floor tiles look great, personally I would feel better using a modern fire brick floor for performance and ease of replacement if ever necessary.

[UtahBeehiver]

Super duty is a common term for industrial rated fire brick. The alumina content is quite high, ie 65% plus and typically used for steel, glass or other type of blast type furnaces. I made my oven from super duty bricks that were new but surplus from a steel mill, they are typically larger or preformed arc or odd shapes. Free is not free, these bricks are extremely hard and they take their toll on wet saw blades, I went through a dozen in my build.

I have had not issues on heatiing up or use in an oven. The key is good floor and dome insulation and a good insulated door. I can easily get 3-4 days work of cooking from an initial fire up.

[Petter]

My opinion:

https://community.fornobravo.com/for...uty-firebricks

[Yellowbeard]

First, thank you to all of you for the responses. It sounds like I CAN use these bricks but it will be at my own peril in terms of cutting. However the sheer romance of using these super old bricks (and their children) for my pizza oven is worth it.

Petter: Can you recommend a source for Biscotto di Sorrento? Are you getting it from Italy?

in case anyone cares, here are some photos of the bricks I am using:

[UtahBeehiver]

I deleted the hyperlink out of a previous post. We try to avoid any commercial hyperlinks on the forum.

How did you determine these bricks are "super" duty. A red color fire brick does not lend itself to being super duty. Try cutting one on a wet saw, you will know if they are super duty or not if they are hard/slow to cut.

[Yellowbeard]

I deleted the hyperlink out of a previous post. We try to avoid any commercial hyperlinks on the forum.

How did you determine these bricks are "super" duty. A red color fire brick does not lend itself to being super duty. Try cutting one on a wet saw, you will know if they are super duty or not if they are hard/slow to cut.

I'm talking about the Wellsville Savage Bricks from my images. They are blond (though it is admittedly hard to tell from my picture). And they were the bricks which the wood fired kiln was made from which FIRED the red clay bricks you see above. That's how I know they are super duty.

My apologies for the offending hyperlink. I didn't know I shouldn't have so, now that I do, I will avoid that in the future. Thank you for edifying me on this point.

[Petter]

I bought my floor from a local (in Sweden anyway) oven importer. It was about 4000 SEK, $450 for a 100 cm round floor.

However, you need to deside what style of pizza you are going to bake. Biscotto di Sorrento / Casapula or Saputo are made for Neapolitan pizza. Typical 40-90 s bakes with soft and slightly spotted char on the bottom. Regular medium firebricks are best from 90 s and up to several minutes and make a somewhat soft to crisp bottom.