Planning my 32" cast oven

[UtahBeehiver]

I use pine or cheaper wood for the initial startup/heating of my oven and finish off with hardwoods for the final stage as well as the live fire while cooking pizza. Gotta use what you got. BTW, nice banjo peel. The banjo peels gets a lot of use with turning the pies, it also get a lot exposure to heat. I just cut off the burnt end of my wood shaft and remounted the ss banjo. Loading of pizzas seems to work better with a wood peel.

[AndreasP]

Good to know, will have to wait a while until the pine is seasoned.
Yes, I bought two wooden peels for loading the pizza.
My banjo peel is aluminum, will have to live with it for now.

[Kris S]

From my experience with our home wood burning stove: lots of people say don’t use pine but that’s nonsense, I burn it without any problems (soot or black smoke). To do this I have to split the logs smaller than with any other type of wood I’ve burnt because pine tends to need more oxygen to have a clean burn, so big chunks of pine will either burn/smolder with dirty smoke (too little air) or get way too hot with flames going partly up in the chimney pipe when you give adequate oxygen for a clean burn. I had to learn through trial and error and seeing your stove go Chernobyl scared the hell out of me! Smaller splits, not overloading the stove and adequate oxygen supply and I can burn pine just fine without visible smoke outside.

I don’t use pine to start my home fire though, because on firing the temperature is still low and smoke does occur with any type op wood, but just more with pine, it’s smoke also smells worse, maybe because of the resin. Pieces with resin oozing out give lots of heat, but more smoke and soot as well.

I haven’t used it in the pizza oven and don’t plan on doing it, but that’s because I have enough other soft- and hardwood.

Anyway I’d season them for at least a year instead of 6 months.

Cherry wood is excellent!

Acacia, I don’t know, interested in this as well! I have some drying right now and ready to burn in the oven next year. It’s a dense hardwood but I read somewhere it can smell funny as well?

[MarkJerling]

I tend to start with good, dry, seasoned pine and once I have a good fire I add gum and finally I move on to cherry, apple and/or olive wood.

[AndreasP]

Made some progress today. It was hot and dry the last few days. In the high 80s. Should have helped drying the oven out.
Was able to put on 2" of insulation around the oven and 3" on the top of the dome. Only have 1" around the gallery, but I will add as much Vcrete as I can in that area
Made another fire and kept it going tor a while. Dome got up to 250F but floor got to 500F+ after I moved the coals.

Planning to do the 10:1 Vermicrete over the insulation tomorrow. It seems there are different opinions if this should be done before or after the curing fires:

• Before: I would not be adding more water to the build once the dome is cured and dried
• After: It might be easier to drive any remaining water out of the dome without the Vcrete on top of the fiber blanket

Any thoughts or recommendations?

Looking forward to pizza.

[david s]

You are thinking along the right lines. I like to do the vermicrete, then leave it for a week to allow the sun and wind do much of the drying, then do the fires.But there are many ways to skin a cat and a fair bit may depend on your weather conditions.

[AndreasP]

Thanks David, will do the vermicrete today. Getting closer to our first pizza

[AndreasP]

Started on the Vermicrete today.
It was a lot more difficult than I had expected. When I opened the bag of Vermiculite it looked like the pieces were VERY big. When I purchased it they said it was medium size.
It says A-3 on the bag, I guess that should have been a hint.

I did the first batch with a 10:1.5 mix (10:1 simply didn't hold together), then went to Home Depot and got some Perlite. The Perlite is much finer as can be seen in the photo.

For the rest I mixed 50% perlite and 50% vermiculite, but as I got higher up on the dome the layers at the bottom started to collapse in some places.
I added a bit more water and tried again, still very fragile.

I stopped half way through and figured I would let it dry overnight. Hopefully it won't all fall off tomorrow when I touch it.
If it looks reasonably solid I will patch a few thin areas with Perlite (the smaller stuff), maybe 5:1 to make it stick better, then continue with the rest of the dome.

[david s]

It looks ok in the photo. The finer stuff is easier to apply but the downside is that it requires more water which means more to eliminate later. I find a mix of perlite and vermiculite works better than either of them alone. Also a handful of powdered clay for every litre of cement helps give the brew more stickiness. More cement drastically reduces insulation value. Once it’s set for 24 hrs it is pretty easy to either carve or ad to.

[AndreasP]

Was able to complete the Vermicrete last night. Looks OK, nothing is falling off once it is dried. This time it was a lot easier to work with. I changed the mix to:
7 parts Perlite
3 parts Vermiculite (I was running out of Vermiculite)
1 part Portland cement
1 handful of Clay
I used more water than the day before.
The mix was a lot easier to work with, not sure if it was the finer Perlite, the addition of Clay, using more water or simply the fact that the dome starts leaning back the higher you get.

Also made a mold for the corner, some of the bottom fell off when I removed the mold after 24 hrs. Will have to patch it later.

David, I am wondering why I should let it dry for 7 days before firing. Is it for the mix to cure slowly (it does contain Portland Cement)? Then again, it is not structural at all.
With the 2" of ceramic blanket it shouldn't get too hot in the first few days of firing. What's the risk for the Vermicrete of starting fire early?

[UtahBeehiver]

Because the v/pcrete has a ton of water in it which probably moved into the ceramic blanket. Wet insulation will readily transmit heat. When water sublimates to vapor the volume increase by 1500 times and the possible pressure could crack uncured portland cement. Don't get impatient, this is where we see a lot of builders want to fire up, going too fast, too hot. You could possibly to some charcoal briquettes fires that will yield about 200 F so not enough to sublimate water.

[AndreasP]

Thanks, I'll try to be patient. Will do small fires for now.

[Kris S]

Yes be patient, and I would also add this: even after the curing fires and maybe the few first below pizza temp cooking fires, don't go full throttle too soon or you'll end up with these nasty dome-wide cracks like I did, which you can see in my build in post #126

Though they look terrible, they seem to have stabilized now, cooked some pizzas, bread, vegetable dishes and a slow cooked meat last weekend without problems.

Of course it could be my homebrew was a little drier or different than yours, you may not experience these cracks (hopefully) but better safe than sorry...

[AndreasP]

Kris,
Yes, I remember your build thread and your post on the cracks. BTW, your thread was really helpful, thanks!

[AndreasP]

Completed the curing fires and made pizza for the frist time yesterday 14 pizzas. Worked out great. The Pizza was some of the best we have ever had, and that was even with dough bought at Trade Joe's!

At the beginning the floor was very hot, 900F+ and the dome was in the 850 - 950F range. The first pizza, a small one, took barely 45 seconds, but tasted delicious. Nice puffed up crust.
As I made more pizzas the floor cooled significantly, even though there was a fire on the side.
I ended up pushing coals onto the floor where I was cooking the pizzas to recharge it, which worked well.
Cooking went way faster than assembling the actual pizzas.

I also started placing the pies in different spots in the oven. The back of the oven was of course much hotter than the front and middle.

Thanks again to everybody on this forum for all your help! I am sure it would not have turned out as well as it did without all of you!