Low conductivity fire brick source

[majulian]

I may be posting this in the wrong place, maybe it should be in Ovens, but this seemed like a good fit with stones, tiles, etc. Moderator let me know if I need to move it and I will. Thank you.

I have built a couple of wood fired ovens and have used Harbison Walker fire bricks for the domes and the floors. They were readily available and have been a good product. They have a thermal conductivity of 1.28 W/m at 800 degrees. Both of these ovens are the FB Pompei design and I've been making pizza in them for several years and have adjusted my firing method to accommodate the floor to some degree. I usually have the floor at about 725 to 750 and the dome at 850 to 950 approximately. This works pretty well but I'm considering trying to find a lower conductivity brick for the floors so I can more easily accommodate slightly higher temperatures in the floor with less risk of burning. Sometimes I get distracted. We've had a couple get togethers where we baked 20 plus pies and I have to be on my toes, heat retention and the ability to run a lot of pies is great, so I have no need for improvement in that area.

I know that Whitacre-Greer has a buff brick that supposedly would be a lower conductivity than what I have, but factual technical data seems to be limited to showing the TC at 86 degrees which is not very helpful. So I wonder if they would be a notable improvement over the 1.28 @ 800f TC of the Harbison-Walker bricks. Any opinions on that question?

The saputo tiles seem to be unobtanium now for individual builders from what I read.

Also, does anyone know of any other lower conductivity fire brick available, similar to the Whitacre-Greer especially somewhere on the west coast? Appreciate any input and help. 

Thanks,
Mark

[TXCraig1]

I've used an oven with Whitacre Greer low density fire brick (buff pavers), and they are too conductive for Neapolitan. Probably fine for NYS. I'd guess they are close to 1.0 W/mK.

Did you try these: 

https://www.biscottostones.com/
https://biscottopizzastone.com/

[majulian]

Craig,

Thanks for the reply. I had seen the "biscotopizzastone" but had not clicked through to the page where they had some larger squares available. Those may be a good option if I decide to head down the biscotto path. I could remove some floor bricks and slice them to reduce their depth to where the biscotto would sit on top. I think that would keep everything pretty uniform heat wise with good surface contact. I'd rather not lose any heat retention area so I'd like to keep the full brick thickness in the floor as we usually cook for a couple days after pizza from the retained heat.

The option of doing some 60 or 90 second bakes is appealing though not a necessity. We've been pretty happy in the 2-minute area and had good results. But I would like to have a little more leeway temperature wise in the floor. Feeling more comfortable at around 800+- floor temp would be nice and extend the cooking time too without much of a recharge.

I was kind of hoping there may be a traditional 2 1/2" fire brick out there that I didn't know about that would serve the purpose. It would be easier to just swap out floor bricks. However, cutting some down to accommodate the biscotto wouldn't be that bad. 

The difference between the potential 1.0 TC of the Whitacre bricks vs the 1.28 of the Harbin may not be worth the cost. Does adding the biscotto to the top of thinned down floor bricks seem reasonable to you?

Thanks very much for your reply and all your input to the forum.

[TXCraig1]

Biscotto on top of fire brick works pretty well from what I've seen. I'd think you could put the biscotto right on top of the firebrick without thinning. The extra height probably wouldn't hurt and may even help. Most oven domes are too high to start with.

[majulian]

Thanks, appreciate your opinion.

[Jon in Albany]

I was able to get my hands on some biscotto during my oven build. It isn't exact, but the biscotto I had on top of a firebrick split was just a little bit thicker than a fire brick. I used fire clay to level it out.

I don't know if he would still ship it or would even still be able to do it, but Simone from Pizza party shipped me some biscotto.

[majulian]

Thanks for the reply Jon. How has the biscotto worked out for you?

Mark

[Jon in Albany]

construction-wise, it worked out well. Use-wise, I probably would have been better off with all fire brick. My oven is half biscotto floor and half Whitacre Greer fire brick. I don't use the biscotto side of my oven that often. The pizza I usually chase is more a standard, American wood fired pizza, 4-or so minute bake at 625 to 650 degrees F.

[majulian]

Thanks, the more I think about it the more I'm leaning back to just changing out my current floor bricks for the lower conductivity WG bricks rather than converting to biscotto type. I think I've decided I'm not really that interested in 60 to 90 second bakes. I'm actually pretty happy with things the way they are, I just manage my fire to keep the dome very hot and the floor in a good range. I'm able to make lots of good pizza in the 2-minute range. I think with the WG floor it will be even easier and may even drop the bake time a little. It's also easy to just change out floor bricks and see how it works.

Thanks again for your input.