42" In South GA

[david s]

All new ovens are somewhat smoky for the first few fires and sometimes it's hard to keep the fire alight, so don't be too dismayed if you get a fair bit of smoke out the front, things will improve markedly once the oven has dried somewhat, also the lack of a flue pipe won't help the situation. I suggest you try it to see what happens and "play it by ear." (or in this case by nose)

[edonovan]

david s Thank you again. I think I’ll wait, the remaining chimney parts will be here Wednesday, so not too long of a wait. Got 2 layers of ceramic blanket down. Yay!! Now to just to keep that dry until I get the pecrete and stucco over it. ♂️
I do have about 15 feet of blanket left over, is it advised to just use it up, say have a 3rd layer over the dome and not the sides? Or (what I am thinking) does that create a shaping issue when I get to the pecrete?

[david s]

Up to you, but if you have the extra blanket, paid for it and have the room to install it, why not use it. It can be way thicker on top, which is where it will get hotter anyway. The vermicrete or perlcrete will even out the form of the uneven blanket. Here's an example of two layers of blanket on the sides, because that's all the room I had, but 4 or 5 layers on top.

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[edonovan]

Alrighty!!! So much progress!!! Used up what I could of my insulation! And threw an old halogen shop lamp in there while I worked on the chimney. Chimney went up great! And have been having a weekend of first drying fires. The charcoal is definitely not as exciting as the first actual fires! And definitely had to have a celebratory drink!!

[edonovan]

Sorry for the sideways pictures

[UtahBeehiver]

Really be patient with curing fires, this is where we see a lot of builders go too fast, too hot and damage all their hard work.

[edonovan]

UtahBeehiver Oh yeah definitely going slow, if there is anything I remember from all my research it is to go slow. As I have transitioned into small wood fires I am finding temp management to be challenging…I’ll see 250-270 on a particular spot on the wall and then lower further away. So I am trying to keep an average and move the fire around. Question, if I don’t see any moisture coming out on my clear drop cloth around the dome…is that a bad thing?

[UtahBeehiver]

Probably not in the temperature range yet at 270 F interior for water to condense on exterior or the blanket is absorbing some of the vapor. Turtle wins the race in curing.

[edonovan]

So starting seeing a little condensation on the inside of my plastic drop cloth, however I wonder if it could also be from it being 98 here during the day and when the temp drops...some condensation forms? I am hovering around 350-450 now and just may stay in this range for a couple days. Is it good practice to move the fires around from middle, back, Left, right? Like I said before temp management is proving difficult, and maybe it is just cause it is a 42"...I shoot 320 on the back wall and 415 at the dome if I have the fire right in the middle, and so forth, higher on the left and lower on the right if that fire is slightly to the left. I have definitely got nervous on a couple occasions as add a "relatively" small piece of wood...starts going up and I shoot the wall nearby and hit 450, however as the flame dies down the wall evens out to around upper 200's to low 300's...this normal?
You all got me nervous on this stage, and you say slow and I say...I can go slower LOL!! As I keep going up in temp, I am good to go all the way just being my blanket on there correct? and once I have that first 800-900 degree fire I can start on my perlite layer?
And on a cool/frustrating note...If I walk away from my fire for a little bit and come back and It has gone out, it is proving challenging to get it flamed up again with a small piece of wood (maybe I am impatient) and it smokes a lot, so I get that cloud of smoke building in the dome...but once it flames up...watching that build up of smoke just fly up the flue is SOO cool!!!

[SableSprings]

You're doing the right thing by moving the fire around...and yes, an oven that's in the early stages of curing has trouble supporting a fire. Sounds like you still have considerable moisture contained in the build, as Russell noted...the turtle wins. As to temp variations, yes that's normal and we've all had that yikes moment when what seems like a tiny piece of wood put us way too hot. Generally those hot spots are just surface readings that aren't a problem, especially when the temp drops quickly after the fire is moved away. Have you considered using lump charcoal to get a more controlled burn? Since no two builds are the same, just relax & rest assured you are doing everything right at this point. Seeing evidence of moisture being slowly driven out is all proof of the slow cure "working". Relax & breathe easy!

[edonovan]

SableSprings Thank you. I did try normal charcoal for a bbq for my first firing but would have to search out some lump charcoal if I wanted to go that route. I think I’ll keep moving it around and just ever so slowly try to creep up on the 500-550 range of surface temps and go from there. I knew my habit of procrastinating would come in handy one day…I can turn this 7 day drying into 10-14 days lol

[edonovan]

Reached some 500-to mid 500’s internal surface temps close to the fire and I would say average surface brick was high 300’s to low 400’s and I definitely got some condensation on the backside top area of the plastic cloth, a proud moment that I am moving at the right pace and driving this moisture out. What are some average temps that I should get on my insulation on the exterior? If I were to see spikes on the exterior I would assume that would that be indicative of a crack? So, far I don’t see anything on the interior as a crack…but it is covered in some thick black soot.
I came across a video the other day and was wondering if anyone has seen the “set and forget” lighting method (obviously when I am all dried out) it is by the Melbourne company? Is this a common way to get to temp for cooking, load up the exterior and build a fairly large raft in the middle? Just wondering what everyone thinks on this one.

[SableSprings]

Yes, it's good to see that moisture heading out of your oven. When your oven is completely cured you should only feel warmth on the outside of your insulation. Generally it's the moisture coming out that's hot (steam), not heat coming out directly through cracks. The soot will start to clear when the brick surfaces start reaching +600F and are dry. Moisture remaining in the brick will "prevent" it from reaching those temps, hence the curing/drying process. As your oven dries out, you'll first see that soot burn off (clear) in a circular area at the top. This clearing will gradually expand downward as the moisture leaves the bricks. Note that with every firing, all the inside surfaces of your oven will turn black as the soot forms on the cooler brick inner faces. A fully cured oven will turn black inside as you star firing and then the soot will burn off from the top down as the bricks come to +600F. The last soot to burn off will be around the lower perimeter bricks...also the last area (and generally hardest) to dry out-especially if the base insulation is perlcrete or vermicrete and no exit holes exist in the hearth slab.

For my bread baking, I rough stack my oven chamber (around 10 at night) with wood pretty full & start my fire up front with fatwood or toilet paper tubes stuffed with greasy paper towels (from wiping out my frying pans after dinner ). I make sure I've got a good fire draw going, then damp it down with my firedoor. The next morning, I will have a good bed of coals & the oven is fully cleared and heat saturated. Since I'm way over bread temps, I spread the coals out & open the oven up a bit to let them burn out. I remove the ash & let the oven cool down to my baking temp target of 575F. I know that's not the way most folks fire up for pizza, but it's my set it & forget it method for bread bakes. I suspect with a little trial & error you'll find a method of firing that fits your time & goals perfectly!

[edonovan]

SableSprings Thank you again. I have been reading over your tool list to begin acquiring tools.

It’s amazing how much condensation I am seeing now that I am holding in the lower 500’s with some surface temps where the fire is getting to upper 500’s. Also, much more even temps, as I would have a mid 400 fire on the left the right wall would be mid 200 and back would be mid 300, no I am seeing more consistency in having a mid 500 fire on right and mid 400 on back and left wall.

It’s official!! I have my first cracks!! I know every says that everyone gets them…but it sure does stink seeing them pop up. One in the back left wall and one at the inner arch. Just wondering, is there a rule of thumb for a certain size crack you should grind out and fill with mortar? Obviously the back wall one would be difficult to do anything to, however the inner arch could be ground a little and stuffed with mortar.

[SableSprings]

No worries on those minor cracks...relax, you've built a great oven! Remember, your oven's bricks expand as they heat up...that's why those cracks are inevitable. Before the advent of inexpensive IR guns & thermocouples, counting the seconds a pinch of flour on the hearth took to brown or blacken was your temp guide as well as knowing which cracks opened up (& how wide) when the oven got to the desired temp. I honestly can't see any reason to think about grinding out/stuffing mortar in your situation... again, Relax!