Bricks for 42" Oven - Question about Refractory Bricks

[wthwaites]

Hello all!

Trying to build at 42" oven based on the plans provided here. Some feedback needed about bricks potentially sourced.
Here in Jamaica firebricks are extremely expensive. Purchasing the firebricks indicated in the build guide will be the equivalent of $2500 USD alone! However, I am able source refractory bricks used within furnaces at a cement plant. They got wet, so they were planning on dumping a lot of what was purchased; I will be able to attain a lot more than i need. These bricks have the code B320 / B620 on them - I believe they are heavy duty high alumina bricks. Rough esitmate of size - 6" x 6" x 3"
Am I able to use these bricks in my oven build for the dome or floor? Or is this a waste of effort???

Thanks everyone!

[UtahBeehiver]

They are probably what are classified as Super Duty, I used a similar size brick (right side of attached pic) from a steel mill but they were new surplus. Only a couple issues with these bricks, my guess they were used to drying their product or raw materials so my thoughts there should not be anything hazardous embedded in the brick. Second, these are really hard brick, both Gulf and I used Super Duty, so they are really hard to cut and you really need a diamond wet saw for cutting (I went through a dozen cheap diamond blades). JRPizza used a method to minimize bevel cut so you can get a tight inside joint with less cutting (see his thread). As far as getting wet, refractory brick suffer when they go through a wet freeze cycle, I don't suspect you get freezing down there.

[wthwaites]

Is that a yes to me being able to use them to build an oven then?
Use for dome, cooking floor, or both? If i build an oven with them, will the oven get too hot when firing up?

[Petter]

I have super duty bricks as well. Actually 95 % Al2O3 for the dome and 57 % Al2O3 for the floor. So far, I have only prepared the dome bricks. They are extremley hard on the blade though they cut well. My bricks are tapered. I ended up only cutting though 1/3 of the brick height and then rest it on a support and hit it with a hammer on the back to brak in halves and thirds. Thats also makes s sort of stepped taper. My initial though was to bevel the bricks, but by doing so, the blade cost alone would be more than the whole oven. I'm going to live with slightly larger joints.

The oven will not get too hot. You control the heat, but it will behave slightly different to a low duty brick oven.

[wthwaites]

Thanks for the feedback.

JRPizza used a method to minimize bevel cut so you can get a tight inside joint with less cutting (see his thread).

Can you provide the link to this thread?

[wthwaites]

Sounds great! I assume I would have to cut them to the regular 4 1/2" x 9" x 2" size or 4 1/2 x 4 1/2 x 2" correct?

My initial though was to bevel the bricks, but by doing so, the blade cost alone would be more than the whole oven. I'm going to live with slightly larger joints.

Whats the benefit to beveling the bricks? Where would you bevel them?

[wthwaites]

I'm trying to look back on this thread and realize that the second page of replies are gone. The valuable information required is no longer there!
Is there any reason for this???

[Petter]

Forum was hacked and reset.

[wthwaites]

Forum was hacked and reset.

I was looking for the detailed advice you provided based on the densities I had recorded and outlined. If I do that again, would you be willing to share again?

[Petter]

Sure, I'll try.

[wthwaites]

Petter Sorry I took so long to respond. Ive been really busy with work recently...

I recalculated the densities of the bricks I have and detailed them in each picture attached. But for ease of reference I'll also add the info below:

• Rectangular "L" Brick - 2,735 kg/m3
• Square Orange Brick - 2,847 kg/m3
• Square Black Brick - 1,722 kg/m3

I believe you recommended the rectangular "L" shaped brick for my dome, but I cannot recall the rest of the advise on what could be used for the cooking floor (if any at all). I appreciate the advice given once more!

Thanks Much!

[Petter]

I believe so too about the dome brick. However, the density different is very small so in reality, use what is the most convenient cutting-wise.

Regarding the black bricks and cooking floor. I've searched here and on pizzamaking.com and your floor of choice depends on your desired cooking time. It also depends on your door size since a large door let more cooling air into the oven. Shorter time and smaller door calls for a less conductive floor, I.e lower density bricks or Italien biscotto di sorrento (density about 1.4-1.5 kg/dm3)

The general conclusion seems to be that biscotto is good for 35-90 seconds pizza while low-medium graded firebricks are good for ~90+ seconds in a heat saturated oven. Forno Bravo states 90-120 s for example.

The Black bricks would be low duty, so expect optimum cooking time in the 60-120s range.

[wthwaites]

I believe so too about the dome brick. However, the density different is very small so in reality, use what is the most convenient cutting-wise.

Regarding the black bricks and cooking floor. I've searched here and on pizzamaking.com and your floor of choice depends on your desired cooking time. It also depends on your door size since a large door let more cooling air into the oven. Shorter time and smaller door calls for a less conductive floor, I.e lower density bricks or Italien biscotto di sorrento (density about 1.4-1.5 kg/dm3)

The general conclusion seems to be that biscotto is good for 35-90 seconds pizza while low-medium graded firebricks are good for ~90+ seconds in a heat saturated oven. Forno Bravo states 90-120 s for example.

The Black bricks would be low duty, so expect optimum cooking time in the 60-120s range.

So in a nutshell - No for using the higher density bricks for the cooking floor, but I can use the black bricks for my cooking floor? I wasn't sure... If I can, that would be great as it would save me a ton of money!
Based on my calculations, I believe my intended door size will be 20" x 13 1/4"

[Petter]

Look here for example

https://www.pizzamaking.com/forum/in..._jschl_tk__=34 7a14c97957871e87c90f05b42c22cad42cd25e-1601917475-0-ASavZiEjK-YcJeVht0xM4hV9bpAEtl2o19k-ysLzUBOkgr8UUkRiHsEIWV4eomGlJmCxULfVJrMP0_sSEEETlJ R2m4cfIp7rmrgIU9mCjhQylbzSw45ndhpP5GyKB7EDG5r95wl1 XRPVnFNoSpiTKAbTVR-19wCdDxtoLcpKjQTC23ASVon-_QkAjqO7l8mM42n5CalHofSxxPsdMRTjZtgTax0mnupKN6u2A9 ueQFo0wBJ3z96ItK1_NUupEbRMxc4pTBMAq4XoiSKG52moZizM MWmbo_LphAPJb_B4TYoBBUTp2SgHHXCYK9IQxUw33A


your black bricks does likeky have a thermal conductivity of 0.7 W/mK. Equal to red terracotta bricks. You will need to make decent fire to get the floor temperature right. Your opening is large compared to the standard r=22 cm half circle of neapolitan ovens. You're not likeky to burn the bottom of the pizzas. If you bake bread, the bottoms may turn out a bit pale.

If it were me, I would use them. I have actually changed my floor thoughts from the 57% high duty alumina bricks to a true Biscotto floor based on summers baking in a small oven and all forum search. Hopefully, it will arrive in a few weeks.

[wthwaites]

Well, I just realized that the black bricks I have are actually tapered bricks, so it will be difficult to cut and level them properly for the floor...
I feel that I may have to bite the bullet and purchase the floor bricks needed. I checked with a supplier here, and they provide medium duty bricks (2,256 kg/m³ or 140 lb/ft³) which would be what Forno Bravo recommends. I'm trying to avoid spending, but I guess this may be unavoidable...