36" Pompeii in Indiana, US

[GreenViews]

I was avoiding cementing in the flue this morning and I now know why. I have new ideas which allow me to use more attractive and unique materials for the front of my oven as well as preserve the rounded shape on the back end of the oven.


shape a mantle: In the front where the angle iron is, make a rounded mantle by notching firebrick to hang over angle iron with front shaped in a semi-circle

Materials: We have lots of the river stone with fossils from back home. It is really unique and awesome. I think I'll cover the front face and just a little ways back on the sides with this. I will frame and put cement board first out from the front edge of the firebrick and then back a bit. I will use the void space to add insulation at the front of the oven, run wiring and maybe add and insulated buttress for my inner arch and front of the base of my wall area.

Then along the front of the curved mantle, I'll cement the small cut stones with copper veins and other unique cut stones. I did a bit of playing and I think it will look really good and unique.

That's my good idea for now, principally the river stone up the front area of the oven and extending up the chimney section to the roof. I have some questions yet to answer like do I need to insulate the clay flue or just surround with other materials? Should I mortar in wire mesh between or from the top of the firebrick forming the curved mantle or will the refractory cement stick to the front face of it without help?

[BeanAnimal]

Don't know, I personally never used, but several builders have and not sure how flexible flexible is. The Uni Extreme I used set up hard though so placing on an highly expanding metal angle may or may not be an issue for Greenville.

As far as the door seal, mine is just a dry fit between the ss steel and the fire brick, is it a 100% seal, no but is does what I need it to do. More important is the have an "insulated" door. Carbon steel has a much higher K value than SS and thinner the gauge better.

I would go further and say that you are not sealing a 1200 degree kiln. I would guess that for residual cooking, by the time the fire is out and you seal off you are at 600 or below. If you want a good seal, then maybe a conventional oven door gasket repurposed?

[GreenViews]

Pause Button: I'm hitting the pause button on any new cement until my baby girl goes off to college. Reason being my most important goal is to spend time with her playing with the new oven as she likes cooking and her favorite restaurant is a local gourmet high temp pizza place. Most important goal: spend meaningful time with daughter before she goes off to college. I'd like a month of experimenting with her with the new oven. That means start cooking July 11th, next weekend. It has been 7 days now since I placed dome keystone and 3 days since I bricked in my entry area.

To accomplish my goals I'm thinking of the following steps: (feedback welcome)

• finish laying final floor of splits in fishbone pattern, but lay with dry sand/clay mix
• create a temporary metal flue and vent with 6" ducting and sheet metal I have laying around
• insulate my oven with the thermal insulation but no pcrete until after she leaves for college
• finish my roof as much as I am able in the given time
• Begin low temp fire curing process this weekend (11 or 12 days after dome keystone and 7 or 8 days since entrance walls layed) so it is pizza temp ready for the following weekend
• Finish getting firewood ready and into covered storage from the open air stacks (been a dry summer, so I think we good)
• make a temp door
• begin reading up on dough, prep, etc

I think this will give me enough time to
I added stucco to one of my firewood storage areas and will begin moving from piles in the yard into this covered storage area asap.

Any suggested modifications? ... with assumptions that my top priority is having a new activity to do with daughter before she heads off to college and therefore time constraint of beginning cooking in oven July 11th.

[Chach]

Just don't rush your cure fires even if its for a good reason. Insulate and take it slow.

Ricky

[GreenViews]

Thanks for the feedback. I'll take it slow. It's been 12 days now since finishing the dome. Yesterday I laid the top floor layer of splits inside my dome with dry sand/clay mix and lit 2 - 6 hour clean burn food heaters. I checked on it after an hour and was getting near 200 inside top of dome, 115 F floor and lower dome. I will finish insulating today and repeat tonight with same low heat source. I am using a temp door of single layer of sheet metal.

[Chach]

Don't forget to insulate the dome as it is recommended to insulate before curing begins so thermal shock does not occur and the oven stays warm longer and more even during the cure process.

[GreenViews]

Placed the flue, base to chimney and mantle last night. Since it is outside the main oven, I decided to cement it in without delaying the drying process too much. I also insulated oven, pics to follow.

[GreenViews]

Work yesterday:

• Glued aluminum edge to bottom front of oven entrance (will have entrance very slightly lower, so this is to protect the front of oven floor (firebrick splits)
• Tucked and glued fiber rope into crack between angle iron for door and inner arch
• Insulated with fiber blanket: most areas of oven with 3 in blanket, some lower ares have only 2 in and 4 places along first half soldier course have none, so I can directly support / buttress with 5:1 perlcrete for structural insurance. I added wire mesh only around the base of the fiber blanket. Just realized I need to cut this away from the areas with no fiber blanket to keep it from being a heat sync carrying heat away from the oven along mesh to outside the fiber blanket. I will cover all this with p-crete.
• Cemented in the flue and mantle areas. I decided on a mantle directly above the entrance which curves out to make it more appealing and make up for the lack of arch in the front of the entrance areas since I decided to go with angle iron supports for chimney and flue.
• Lit 2 more 6 hour food warming candles which seem to create a top temperature of around 200 F and loosely sealed the doorway with sheet metal

[P3 Stoaker]

G'day Tom,
WOW, impressive progress so quickly. Was only a few weeks ago we were at the same stage. I see you have reasons though, getting some quality time with your daughter.
Initially I had hoped to complete my oven for my Son's 18, but that was last Friday and that ship sailed quite a while ago.
Regards

[GreenViews]

HELP, what does 300 F curing fire mean? Fire pictured was waaay too hot. I couldn't get the darned thing to stay lit at first, then woosh, takes off and I'm 500F everywhere for a while. Sooo... is 300F temp mid-height of oven? on Floor? This I can get close to, but even with a tiny fire (I've been learning to regulate it better through the few hours since I started) the temp at the top of the dome is always 500F or so. While having an active fire even with a few very small twigs burning, I've not gotten the top of the dome below that temp. Any thoughts on what a 300F curing fire means????

[Mongo]

I think a 300f curing fire is shot on the dome above the fire.
All those flames even though they come from what looks like small twigs are producing a very high temperature spike. Even crumpled newspaper can produce a crazy amount of heat for a very short time.

I was very paranoid during my cure and took some notes and photos. I can offer you what I did and tell you that as far as I know, there are no cracks in my dome. At least none that I can see. Honestly I haven't really looked that hard.

Don't use the wood you are using for your initial curing fires, and don't spread them out like in our photo until later on in your cure. Keep a nice small compact fire.
When I first added a 'normal' stick of firewood to a fire it flamed up and created like a 150 degree spike. I freaked out and removed it with tongs and the temp came down almost immediately.

My first fire was a small pile of charcoal and a tiny piece of hardwood kindling.
I continued to use charcoal but just added more kindling, and still use charcoal to start my fires. Works great.
Think I did at least 6 fires before the inside of my dome even turned black, and didn't 'clear' the dome until about my 10th fire

These are my rough notes and a few pics.
I took temps at the apex of the dome and at about 3 bricks up from the floor. Where I list 3 temps, they are apex, 3 bricks down, 3 bricks up.
Day Temps
1 125 / 80.
2 150 / 80
3 190 / 100
4 250
5 300 / 180
6 400+- / 210 / 200
7 530 / 480 / 350
Stopped taking notes at this point.

Photos are my day 1 and day 6 curing fires.
Interesting that on day 6 there was what looked like a lacquer coating on the dome but no black soot yet.

Summary: use charcoal, keep you fires small and compact and control your flames.

[Chach]

Small fires go very slow. Yes the fires can get big very fast just don't put a ton of fuel in. Keep an eye on it you can always use a small metal shovel to take some wood out while its lit to make the fire smaller if it gets to big or spread it out to even out the flames.

Ricky

[P3 Stoaker]

G'day Tom,
Hope the 'firing' is going well.
I noted you used fire clay under the first course. Was it 50% sand?
My floor is fairly level but a couple of the edge cut bricks are a little lower and the dome first course will likely sit back a little kicking the front edge up. So I plan to start without fire clay at the highest point and use the clay to keep the course level.
When purchasing the fire clay the salesman knew it was for a pizza oven but no detail. He advised me it wouldn't set and would wash away with rain or water. Whilst it shouldn't get wet and I don't plan on hosing it, I do wonder about its weight bearing strength? I know the advice is 50/50 fire clay and sand but I can't imagine sand increasing it's strength. So I'm now wondering if there is a difference in the product here in Australia compared to USA, I know other products are significantly different to the point I'm cautious and like to avoid a disaster.
What did you use and what ratio? I might mix up a little for a test.
Regard

[GreenViews]

Greg, Yeah I used a 50:50 mix of fireclay and sand (I used fine silica sand, but others have used other). I think any good clay product is fine. To keep from relying on the clay/sand layer to hold up the brick if the difference is more significant, one idea would be to not vary the sand/clay layer much, but rather bring the second and third course into level by adding a little to each of your joints on the low side of the dome or alternately cutting your bricks a little thicker on the low side until you are nice and level. That would put your correction in the stable material rather than the float material. But I don't have enough experience to know if you would have problems and I'm sure it would depend on the amount of correction you are talking about. Regards! Tom

[GreenViews]

Ricky and Mongo, (and others who gave me earlier instruction which I failed to heed though I tried)

Thank you! I saw your posts after half the day was done and I let my fire mostly die out as I was running 500F at the top of the dome and 250 to 350 down lower on the dome. You may have saved me from doing further damage to my oven.

The Problem: Oops. Note to future builders... Yes use charcoal as others recommend.... unless you are a better fire maker than I (and I'm not a novice) a wood fire is really hard to keep going that small in your confined oven. I alternated between a small fan at an angle in the entrance and no fan, depending on how much smoldering or burning was happening at the moment.

The Not Perfect News: I did early on in the day see a couple mortar joints near the base of the dome drop a little mortar resulting in a at very deepest 1/4" deep groove in the mortar joint. (I probed it this morning with the tip of a trowel). This morning I peeled back the outside and did not see anything visible on the outside, so this seems to not be a crack as much as mortar failure from heat shock. I just went out and checked again and I have a small mortar joint crack in the inner arch as well. I will later go back and tuck point these joint areas, so it seems no permanent harm, but I overestimated my ability to control the fire. I'm glad I had the 2 days of 6 hour food heater curing and a couple weeks of sitting before this. Probably helped keep damage to a minimum. Nothing to do now but move forward... but with charcoal today, lol... goodness.

Refractory Mortar Note: The Heat Stop 50 mortar held up better under heat shock than the Acona Medium Duty Refractory mortar did. All my issues happened in areas where I used the Acona product and the higher temp areas at top of dome where I had switched to Heat Stop didn't show any problems.

The Good News: This morning without an insulated door, my top of dome temp is 270F and floor is 220F, so my oven held this temp overnight, which I suppose is also representative that I added heat too fast, but the good part is my insulation is doing its job . Also good news is none of my problems are structural issues or issues I cannot fix (even if imperfectly) later.

Humbled by my lack of fire control, but determined to take it all in stride and be happy.
Tom