Homebrew cast oven by the sea

[CoastalPizza]

If you don’t insulate it then it will crack. A 10:1 vermicrete mix around it will work well. You can then stucco over the vermicrete.

Looks like I'll be coating the clay flue pipe with insulating mix (perl- or vermicrete) before stuccoing - found this video that show what happens to uninsulated flue pipe during rapid heating:

[CoastalPizza]

I reached a big milestone - I finished the perlcrete covering and the touch-up of the vent arch. I wanted to be sure that the insulation layers have plenty of ways to exhaust water once I start firing the oven so I built in two vents. The first (already shown in a previous post) is a vent at the apex of the dome. The second is a vent internal to the chimney arch. I used a 1" diameter plastic pipe (well waxed) to form a channel from the RockWool layer to the inside of the chimney arch (see photos). The pipe was sloped down so that any rain entering the chimney won't run into this vent.

[CoastalPizza]

I know its better to dry out the insulation before adding the render but the home-brew casting hasn't had enough time to fully cure so I'd need to wait another couple of weeks. Since I'm not going to be able to work on the oven for the next few months, I decided to go ahead with the initial render coat. I have the two vents (apex and the one in the flue arch) plus the 30 or so small (4-5 mm) holes in the lower part of the dome (from the spacers between the inner and outer ring molds) so it should still be possible to get it fully dry when I finally fire it.

Here are a few pictures: sand coming out, a couple of side views (my wife says it looks like Bender's head), a front view, a close-up of the landing (there is a heat break between the hearth and landing fire bricks), and, a view of the inside (you can see some of the spacer holes).

[CoastalPizza]

So the oven has curing for about 4 months; finally time for the first fires. Started out with a handful of "head beads" following by a couple days of fires, each one bigger than the one before. The outside of the oven got quite warm on the second day; registering 140-145°F adjacent to the vent at the dome's apex. By the third day, the outside dome temperature was no more than 85-90°F even though the inside was getting hot enough to clear. I'm still getting some moisture 'leaking' out at the oven's base - this is probably steam condensing as it cooks out of the base (4" of foamglas + 2" or so of perlcrete under the firebrick floor).

[CoastalPizza]

The first pizza were a success! I attempted to use the top down fire approach but it required several retries to get it going (lots of smoke!). Eventually got it going though but dinner was a couple of hours later than planned.

The dough was a 2 day sourdough fermented at 55°F, toppings were a mix of mozzarella & provolone, fennel sausage, and a oil-cured/kalamata olive mix. The pies cooked in about 90 seconds - I measured a floor temperature of about 800°F.

After pizza, I installed my insulating door - at 11PM it had stabilized at 630°F and by 8 AM this morning it was just over 500°F. Thus, it looks like bread the day after pizza is going to work.

Now I have to get to work and finish the adjacent counters, patio, and put down some sort of paving stones to finish this all off!

[CoastalPizza]

The sourdough bread was not as successful as the pizza - I didn't let the oven cool down enough and I don't think I waited long enough after removing coals so it came out a bit overdone. The steam generator did work pretty well though. The oven was about 450°F when the bread went in. What oven temperature have others used for bread? How long do folks usually wait to the oven to equalize after raking out coals & ash?

[CoastalPizza]

Act III --- overnight pulled pork. Into the oven around 9PM (oven at ~260°F), closed up with the insulating door, done (meat internal temperature ~200°F) at 9AM (oven at ~220°F). Smoke for the first 3-4 hours using an A-MAZE-N Pellet Smoker.

[SableSprings]

The sourdough bread was not as successful as the pizza - I didn't let the oven cool down enough and I don't think I waited long enough after removing coals so it came out a bit overdone. The steam generator did work pretty well though. The oven was about 450°F when the bread went in. What oven temperature have others used for bread? How long do folks usually wait to the oven to equalize after raking out coals & ash?

I bake my baguettes at ~575F for about 15 minutes. My sourdough loaves bake at 525-550F but only for 20 minutes (or until I get to ~205F when using my instant thermometer probe on the loaf) It looks like your bread's crumb is good, just a bit too long in the oven I'd guess (especially at only 450F). I'm assuming the temp reading was cooking floor with an IR gun. So, since your dough spread out quite a bit, I'm assuming this is a high hydration dough and might have used a bit more gluten development...but again, your crumb looks just fine. A wetter, well developed gluten dough might have given you more open crumb...but I'd be happy with your results any day!

How long did you bake these loaves? Also be aware that the cooking floor will vary in temperature (rise) if the deeper brick is hotter than the surface...that's why equalizing the oven after fire/coals have been removed is so important to baking. I suspect you did bake the bread on higher temperature floor bricks than you expected (your bottom crust is quite thin...indicating more heat than noted), but time on the floor and "sugar content" of your dough probably were the main contributors to that crust. Lean, wet doughs will take higher temps OK, but when you do enriched breads the extra sugars will cause the crust to "over caramelize ". There are a lot of bakers who like a hard crust with more than a touch of extra dark color. I'm not a fan, primarily because I've cut my mouth with some of those really hard crusts.

Hope that helps...and be aware that consistent success with pure sourdough breads is pretty difficult to achieve (but still worth every bite ).

[CoastalPizza]

... since your dough spread out quite a bit, I'm assuming this is a high hydration dough and might have used a bit more gluten development...but again, your crumb looks just fine.

It was about 68% hydration - I'm pretty sure that the spreading was because it was over proofed. The oven was still to hot when it was really ready. Waiting dropped the oven temperature but resulted in a spreading loaf.

How long did you bake these loaves?

About 30 minutes which is how long they take in the regular oven. Obviously too long.

Also be aware that the cooking floor will vary in temperature (rise) if the deeper brick is hotter than the surface...that's why equalizing the oven after fire/coals have been removed is so important to baking. I suspect you did bake the bread on higher temperature floor bricks than you expected (your bottom crust is quite thin...indicating more heat than noted)

I do need to wait longer after removing the coals so that the oven is more even.

..but time on the floor and "sugar content" of your dough probably were the main contributors to that crust. Lean, wet doughs will take higher temps OK, but when you do enriched breads the extra sugars will cause the crust to "over caramelize ".

This was a lean dough: just flour, water, salt, starter. I just need to time it right, shorten the bake time, and be sure the oven is equalized.

Thanks for all the pointers - I'll be trying again next weekend.

[CoastalPizza]

I added a render coat of Quikwall surface bonding cement tinted with Bonway Red Ironoxx dry powder pigment. Even though Quikwall claims to be waterproof (it is used to line water tanks), I'll be applying Seal-Krete concrete sealer once it cures for a week or so.

[ThePizzaGuy]

Great helpful thread...thanks for documenting it.

[Yokosuka dweller]

Very unique and cool looking oven. I'm researching for a cast oven myself so this has been really helpful - thanks!

[CoastalPizza]

Two years later and still going strong. I added a chimney about 1.5 years ago (clay flue covered in perlcrete, covered in stucco). We have guests for the weekend so it was pizza night even though it was raining. 3-day 55°F fermented dough (2.3% sourdough starter). My brother-in-law held a umbrella while I prepared & cooked pizzas. My other brother-in-law cut them and brought them inside to the oven set to 170°F. Finished with a lemon drop.

[ScottABreaux]

Has the Quikwall held up on your build? I just ordered a few bags to cover my oven. The chat support on the quikrete website suggested I "try" it, but they weren't familiar with wfo's enough to give me a guarantee that it would work.

[CoastalPizza]

The Quikwall is much better that regular stucco in this application. The alkali resistant fibers in the Quikwall both reduce the number of cracks forming in the dome, and, once a crack occurs, it slows the growth of the crack. It isn't very pretty since you can see the fibers so I added a finish stucco coat that I tinted with orange iron oxide pigment. This fall, I sponged on some thinned tinted finish stucco the morning after a pizza session so that the few cracks would be as open as possible. I then reapplied Seal-Crete concrete sealer --- the above picture was just after the refresh.