Heat retention for bread

We would like to use the Mattone Barile Grande primarily for bread. Should we increase the thermal mass?

Hi Frank,

Good luck with your build! For bread you want to maintain a steady temperature over a relatively long period of time (as I’m sure you already know, thus your question!). The way to increase thermal mass is to add an extra box (2 more layers) of the ceramic fiber insulation. For builds in warmer climates, you’d be fine with one box if you were doing primarily “hot” applications like pizza baking. But for steady heat, like you want for baking bread, and also in a colder climate, a third and fourth layer is a good choice.

The way I think of it is that a second box of ceramic fiber costs more up front, but once the oven is built I wouldn’t have a second chance to install it if the insulation proved to be inadequate.

Thank you. I will definitely use an extra layer of fiber. We are also planning on choking the entrance, using an insulated door, and considering putting the chimney outside the door. Do you know the potential number of loaves from one firing?

Choking the entrance is a great idea. You don’t need a lot of space vertically to slide bread in and out. Definitely follow the ratios in the instructions, or you’ll have trouble starting and maintaining your fire.

The insulated door might not give you as much return, because heat radiated from the floor will tend to go up, not out; still, it could help.

No opinion on placing the chimney outside the door; I think that’s a question that @BrickWood would better understand in terms of the design.

As for number of loaves, it sounds like you are planning some significant bread production from this oven! My best WAG would be six to eight common loaves at a time, or four to six boules. With the oven stopped up as you are planning, you are depending more on stored heat than a live fire for your bake.

If there are other Barile Grande users who are baking bread, I’d love to know more about their experiences!

Good luck, Frank!

Is rock wool a good insulation for pizza ovens. I have access to this product in abundance

Hi Josh! I think rock wool (a.k.a. spun mineral wool) is an edge case. It is rated to withstand temperatures between 1,200°F and 1,500°F. The ceramic fiber blanket is rated for 2,300°F, which you’d need in industrial foundries and kilns. I think that’s another great question for @BrickWood because it involves design specs and efficiency.

Ok. So if I was to use it over the mattone cupola, already a huge mass of refractory cement it would never see temps even close to its max rating and still work as an insulator to retain heat? Thanks!

The cupola is a very different structure from the Barile (where this thread is posted). I’ve asked Kevin @BrickWood to take a look at your question, Josh.

Hey Guys -

Sorry I’m late jumping in on this! If you are looking for a bread oven… primarily a bread oven… the Mattone Cupola is the oven for you. It’s made w/ Castable Refractory, has no seams / joints, and is up to 6" thick (diagonally) in some spots. While it is thicker - it will hold heat for days!

The opening is perfectly sized for heat retention, smoke distribution and draw / air flow, so there is no guesswork on door size. And an insulated door can be made or added later.

As for the blanket - Matt mentioned that the temp rating for the Rockwool is between 1200° - 1500°. That’s kinda on the low side. You really want a blanket that’s around 2500° - at least for the first 2 layers of blanket. After that, you can cover those 2 layers w/ your Rockwool for additional insulation (you can also use it to create a classic “Dome” shape on top of the Mattone Cupola oven).

Kevin