42" Pompeii at the Concrete Casa

[michaewa]

Re: 42" Pompeii at the Concrete Casa

Hey Dino - Cheers! Your thread was one I have frequented and took a lot of cues from. I really appreciate the feedback!

I planned it out so my indispensable tool didn't adjust, but would top out at 19" with a mostly flat plug - like drseward's oven. Amazingly, it looks like it will work out just about right.

[michaewa]

Re: 42" Pompeii at the Concrete Casa

I fused two bricks together yesterday and spent some time this morning shaping them with the saw and grinder to make my plug for the oven top. Just as I had nearly completed it and was thinking how proud of myself I was, I looked in from the inside and realized that since I joined two bricks on the long edge my plug was only half as deep as it needed to be. One of my classic mistakes.

I started over correctly and will hopefully seal things up tomorrow.

I've been reading a fair amount on thermocouples on here today, trying to decide if it is worth it to me. I'm not much for graphing the thermodynamics of my dome, but do plan to use the oven to bake lower temp items. I got a suggestion from Omega to go with this thermocouple and this reader.

I can't really picture how a 6" probe would work - if you embed the probe partway in the dome (e.g. at the top) does the remainder of the probe just stick up in the air, or can it be bent over? I know next to nothing about these.

I don't have power in my dome structure itself, but I'm thinking of using the approach that someone on here (Dino?) took of using a solar panel and a car battery in the enclosure to run a few lights, and the temperature readout.

Any suggestions on those products, or any reason why they wouldn't work? I would just drill in through the side of the floor, and put another on top of the dome.

Cheers!

[michaewa]

Re: 42" Pompeii at the Concrete Casa

Got the keystone(s) in today. My fused bricks didn't work out quite as planned, they came apart while shaping to fit. So I shaped each individually and wound up with the three mortared together and then fitted in all in one shot - worked quite well and fit snugly with no need for bracing beneath.

Quite a good feeling to have that behind me.

The next question is curing...I have the dome covered with a few wet towels and a sheet of plastic to keep the mortar hydrated (as I have through much of the build) and plan to keep it so for about a week.

I have read copious posts on curing, but have not seen much about whether to wait until my outer arch / vent / chimney is in place before starting small fires? Is there harm in starting to cure the dome itself before that is complete?

Cheers!

[KraemerBAC]

Re: 42" Pompeii at the Concrete Casa

[QUOTE

I have read copious posts on curing, but have not seen much about whether to wait until my outer arch / vent / chimney is in place before starting small fires? Is there harm in starting to cure the dome itself before that is complete?

QUOTE]

I have had the same thoughts an would be curious to see how people have handled it

Peter

[michaewa]

Re: 42" Pompeii at the Concrete Casa

May have cut my last brick today. Set the 2nd inner arch, vent walls, and outer arch today. My plan is to cast a vent, just need to get my hands on some castable refractory.

I followed a suggestion from the Good Doctor (drseward) to leave some space between the dome and the vent to reduce heat transfer. That is the reason for the funky bricks for the 2nd arch. Worked pretty well, I will put some scraps of insulation in that space to isolate the dome from the vent as much as possible.

Building the form for the vent is going to make my head hurt I can tell.

[michaewa]

Re: 42" Pompeii at the Concrete Casa

I cast my vent last weekend. I spent more time than I needed to on the forms, but I had never worked with castable refractory before. Very strange stuff, for me anyway who is used to concrete. It was really dry and crumbly when mixed per instructions, but set up hard as a rock.

I'm going with a gas burner on some black pipe to cure. Started this afternoon, and my goal is to hold the dome temp between 190 - 200 until I can get close to that temperature on the outside. Right now inside temps are good, the top of the outside of the dome is around 135F.

The only question I have regarding the cure is one I've seen asked but not answered. The plans and conventional wisdom calls for cycling (e.g. heat to target temp then cool to ambient), but I'm not sure I understand why. The castable refractory curing schedule calls for gradual stepped increases, which seems logical. Any thoughts as to the benefit of allowing the oven to fall to ~90 before ramping up again?

No insulation yet, I'll add that before I step up to the 350 F range.

Thanks to all for your help and inspiration, I really appreciate it.

[Dino_Pizza]

Re: 42" Pompeii at the Concrete Casa

Good questions. I agree with you, it seems that driving the moisture out with sustained low heat is the goal. I believe (because I did NOT do it this way) that others who used a propane or gas burner or a small electric heater/fan kept them on for a day or more at a steady rate. I hope someone can confirm this.

I went with fires only (I dont recomend that; turned my head, flames went up, crack happened) and that naturally lends itself to heat up/cool down cycling which so far has worked for most of us in the past.

I think your plan of warming it until outside temps equal inside is a good one. Also, I kinda wish I put in a thermocouple as well. So I hope you do. Just for a more accurate cooking temps but lasers work and wfo's are excellent at cooking.

It was good you kept the oven moist & covered but be sure to let it naturally dry out a week before you put the burner it. I think natural heat evaporation is good before you force it out. If the oven is ready for curing after a drying period, I think it's ok to start curing even though you may have barely finished the outer arch or vent.

I wonder what others have done.

[michaewa]

Re: 42" Pompeii at the Concrete Casa

Dino - Thanks again. Continue to be impressed that you come back to offer your experience after your build is complete.

I'm at just over three weeks since I finished the keystone, two weeks since I finished the arch / vent support, and not quite one week since I cast the vent. I moist cured the vent, but while that and the arches were curing the rest of the oven was drying out.

I feel pretty comfortable that it had 'seasoned' and I'm going to take it very slow with the gas fire. Overnight my burner somehow went out, but I started it back up this morning and draped some of the ceramic fiber insulation over the top to hold in a little more heat. It is reading ~220 directly over the burner on the inside top of the dome, and around 180-190 at most other internal points with the exception of the soldiers. Still between 130 and 140 on the outside of the dome, we'll see where I get today with the addition of the insulating blanket.

I've got my eye on a thermocouple setup and will probably buy it but my IR thermometer is working great for the time being. Plus my dog freaks out when I shine it on the ground, she will chase it until she is exhausted.

[michaewa]

Re: 42" Pompeii at the Concrete Casa

I had a slow steady heat for nearly 24 hours with the inside top dome ~200. I turned it up a tad this morning and got busy doing something else for a few hours, and checked back to find it was 350 on the inside top and over 200 on the top of the outside. I guess the moisture that has been regulating temps is starting to abate, I didn't expect it to heat up that quickly. I pulled up the insulation and there were a series of hairline cracks where I had filled in the fat joints with mortar, but the inside looks good as new.

I'm not worried about those small cracks unless someone tells me differently, I figured with any amount of expansion there would be some of that.

Cheers...

[michaewa]

Re: 42" Pompeii at the Concrete Casa

Just about done with my enclosure, taking a bit longer than planned because I switched my roof line halfway through framing. Planned on a peaked roof, but I have an overhang on one side where there will be a prep countertop, and that created a huge blank space above the oven door. Switched to a single slope roof which I like much better.

I'm probably going overboard, but I lined the inner walls with cement board about 1/2 way down, and sheathed the outside in OSB. The inner chamber will get filled with vermiculite above where the cement board starts, so the oven will only 'see' completely non-combustable materials.

Had a few 'cheater' pizzas along the way with my curing fires - just some toppings on a flour tortilla (Blasphemy!). The first try I completely fried the crust, but got better from there.

Last night my wife made crusts with some caputo flour. I think there were a combination of factors at play, but the pizzas came out looking like they had been cooked in a blender, not an oven. The crust was too sticky, and wouldn't come off the peel, just tore apart. Is that a function of not enough flour on the bottom? Also, I think the oven wasn't quite hot enough, as the crust was still pretty pliable when I tried to turn them a few minutes in.

The tomato sauce was made with crushed tomatoes, and a bit watery - not like the thick tomato paste I've used in the past. I think that may have contributed to the stickiness of the dough.

Everything we could scrape up was obviously eaten, and tasted fantastic!

Any suggestions would be appreciated...

Cheers!

[Dino_Pizza]

Re: 42" Pompeii at the Concrete Casa

Hi Andy,
Just a few pizza pointers:
First, you are correct, when you get hotter temps the crust will greatly improve. That capuo flour will really sing at close to 800 deg.

You say pizzas stuck to the peel. This may not be what happened to you but we all (ok, maybe some don't, but should) hand stretch the dough on a heavily floured surface, that is NOT the same as the pizza peel we will be placing the pizza on and into the oven (the 'placing peel'). I usually stretch the dough on a very large metal pizza tray, sometimes a large smooth plastic tray, something big enough that will contain my flour dust and not spread it all over the kitchen. Once it is spread and the right diameter, I shake it (ya, it contracts a 1/2" inch) then slide it on to the heavily floured wood peel where I put the toppings on (no longer than about a minute and I usually give it a shake to be sure there is no sticking while I dress up the pizza) then slide it into the oven. That way the pizza dough is not on the same floured surface for 5 minutes getting sticky. Many use grainy semolina or corn meal on the "placing peel", I always use rice flour that releases even better.

I used canned crushed tomatoes recently too but I slowwwwly simmered it for 2 hours to thicken it up but not really cook it.

Great pizza's will soon become an easy thing for you and your wife.

Are almost at pizza temps? 800-900 deg or still curing?
-Dino

[michaewa]

Re: 42" Pompeii at the Concrete Casa

Dino -

Thanks for the great tips. We had MUCH better success the second time using the method you described. We staged the pizzas and used more flour on the prep surface. Just to be safe I pre-cooked the crust for just a few seconds to firm it up, then we pulled it out, topped it, and finished cooking. Best pizza I have ever had, bar none.

I did have the over much hotter too - my Dad dropped by for a visit as I was firing and ended up staying for a few hours, so I kept the oven going at a little over 800F for several hours. It was completely heat soaked, and I had no problems making carnitas the next day and drying peppers from the garden for the next several days. I would say I'm fully cured - there haven't been any cracks inside the dome, just a few hairline cracks in the outer arch.

I just finished the insulation, I have two layers (thicker in some places where it overlaps) of the insulating blanket wrapped from one side of the vent to the other, and I dumped in 32 cubic feet of vermiculite over the top of that before sealing it up. I've yet to cook with that extra vermiculite in there, I don't think it will make a huge difference but should help a little bit - I'll find out this weekend.

My enclosure is almost done being roughed in I put the membrane and drip edge on the roof last night. I'm thinking of planting sedum up there for a living roof, but still thinking through the weight of that to see if it will work.

I just have to pick out the exterior finish material and get that going, and I ordered the same lights as you, they should be here in the next few days. I'm going to try a solar panel mounted on the roof and a little battery to see if that gives enough juice to light the door area and countertop.

Cheers!

[Pompeii Nate]

Re: 42" Pompeii at the Concrete Casa

Hey Andy,

I just read through your thread and was wondering a few things: First, how does the finished oven look? Any pictures? Second, how did the solar panel and battery idea work out for you? I would love to hear.

thanks,
Nate