42” Pompeii oven and Argentine bbq on California Central Coast

[Michele Enrico]

That's a really nice complement Mr. Slowhand. Thank you. I am not intending to use the oven for long term baking so I may leave the structural bricks as the finished exterior. That said the trick is a heavy duty sponge. I scrub the days work with a wet sponge after the concrete has set firm but still green. Any residual after it is totally dry can later be cleaned up with diluted muriatic acid.

[mongota]

This is how I jigged up to make two bricks in three cuts.

When you get higher and transition from half- to third-bricks, you can use the same technique. Four cuts to get three third-bricks.

[Michele Enrico]

Five courses up and still on the bubble.

[Michele Enrico]

mongota, thanks for the tip. When do you recommend going to 1/3 bricks?

[MarkJerling]

....I am not intending to use the oven for long term baking so I may leave the structural bricks as the finished exterior.....

It's said that, with no insulation, when fired, the bricks are much more likely to crack due to the differential from hot to cold, inside to out. I don't have any proof for that, it's just what I've read here.

[Mr. Slowhand]

It's said that, with no insulation, when fired, the bricks are much more likely to crack due to the differential from hot to cold, inside to out. I don't have any proof for that, it's just what I've read here.

Michele Enrico, I must agree with Mark on this one. Having spent a lot of time on this site, before starting my build, this is one of the general knowledge you pick up. The isolation is important for structural safety of the oven as much as it is for the heat retention. Having said that, there are more experienced builders here, that would give you advice.

Again, excellent craftsmanship, keep up the good work!

[Michele Enrico]

Mr. Slowhand slowhand and MarkJerling interesting information about the cracking. Maybe it cracks anyway and you just can’t see it because of the insulation. haha
There are a lot of brick ovens out there with no insulation perhaps warming the oven more solely might help avoid temperature shock.
Michele

[david s]

Mr. Slowhand slowhand and MarkJerling interesting information about the cracking. Maybe it cracks anyway and you just can’t see it because of the insulation. haha
There are a lot of brick ovens out there with no insulation perhaps warming the oven more solely might help avoid temperature shock.
Michele

Watch this on thermal shock.
While a brick oven has much thicker walls than a flue tile, the same principle applies leaving an uninsulated oven more vulnerable to thermal shock (cracking)

https://www.youtube.com/watch?v=bxOkwQyY-2w

[Michele Enrico]

My grandfather once told me “ it is better to remain silent and be thought a fool than to speak out and remove all doubt”.
Well here goes. It is my understanding that thermal shock is caused when a material is heated and expands beyond it’s elastic capacity. Most often cracks occur by heating a material too quickly. I am not sure why an insulated layer would prevent that. I would like to see the chimney sweep video with an insulation blanket around the clay pipe. I am guessing that at that rapid acceleration of heat it would have still cracked. I really don’t know what I am talking about but it is fun to speculate.

[JRPizza]

The downside of uneven heating is uneven expansion, and with brittle materials resultant cracking. It's why a glass plate will explode when placed on a burner but won't if slowly heated in an oven. The thought is insulation helps keep the heat and expansion more uniform.

[Michele Enrico]

JRPizza I see what you are saying.

[Michele Enrico]

Hello all, I have been quietly making progress and am close to closing the dome. But the part I just can’t seem to get my head around is the interface between the inner arch, the outer arch and the flu box. In some photos it appears the outer arch is really a double arch and in some photos it butts the inner arch to allow for a thermal gap.
I guess my question is how do you span from the face of the outer arch to the face of the inner arch with the bricks that make the sides of the flu box. I will be using an 8” dura tech flat plate to mount the chimney pipe to this structure. And my bricks are a standard
9 x 4 1/2 x 2 1/2
Any help would be greatly appreciated.
Michele

[UtahBeehiver]

This is how I did mine but there are other ways as well. Be sure the you vent opening in the brick vent chamber has at least the same square area as the ID of your 8" duratech.

[Michele Enrico]

Russell thanks for the reply. It looks like you really have two arches that make the gallery. The outer and the inner horizontal bricks. As the outer arch is purely a architectural and continuous I am not concerned with that. With regard to the gallery is there a 1” brick at the front and the back at the top of the horizontal brick arch to keep the horizontal gallery bricks in tension and create a flue hole? I would need to see the top view of the gallery before you placed the flue box bricks. Below is a quick sketch to show 1” bridge brick front and back to support the gallery arch and ultimately the flue box. Am I on the right track?

[Mr. Slowhand]

Michele, your WFO is coming great. As you say - silently coming along.
I will put in my 2cents on the flue gallery, for what it is worth. Just completed my WFO structure and for the flue gallery I have two arches and a heat gap.. I was planning to make the flue and "seat" for the chimney anchor also with bricks.
After some discussions, I just used the sand mould, and casted the flue. Ended up looking good, and was an easy exercise. I could have made the outer part much smoother and nicer, but did not spend any time on it, as I am making an enclosure, so will not be visible.
Most of all, even with high smoke levels, nothing was coming out through the front of the oven. As I understand, that has to do with the natural smooth slopes of a casted flue, compared to one you could make while doing it with bricks. It is made with the homebrew, while adding PP fibres and some AR fibres (I used basalt).
Another thing that helps is that you need to do only the vertical bricks of the flue gallery. As soon as the "arch" begins, the casted part of the flue takes over.
There are some consideration if you are casting the entire WFO, should you do it in sections, to allow for differences in heat expansion. This is absolutely not the case for the flue gallery, as it does not heat up significantly.

Anyhow, however it goes, I hope you will finish it soon!!! Good work!!