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  • MarkJerling
    replied
    Originally posted by david s View Post
    Be careful with the construction of such a door. Others have built similar and the reduced air intake makes the fuel:air mixture more like the ideal. (search "blast door") This results in the fire starting to roar. We used to do this trick to our fireplace as a kid, holding a large sheet of newspaper across the fireplace mouth allowing a limited airspace at the bottom. The problem is that the fuel content is so hard to control with wood, that the fire roars away forcing a heat rise that's way too fast for the dense oven to cope with. It is the equivalent of firing a kiln at full blast from ambient, something a potter would never do. As the oven is particularly vulnerable when it still contains moisture this practice could end up doing irreparable damage to your oven.
    Once your oven is dry the smoke issue should disappear.
    Ah, thanks David! Coincidentally, following a long, wet winter, I started a small fire Saturday to dry the oven out. The dome stayed good and dry through winter, but the floor does get wet because of driven rain getting in on the floor below the door. I can see quite a bit of moisture being driven out through the floor drainage holes, especially with the addition of heat.

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  • Sixto
    replied
    Originally posted by david s View Post

    Very nice. You may be interested in my gas fired kiln, which I used my pizza oven moulds to make part of it.

    https://community.fornobravo.com/for...608#post446608
    Beautiful! - I assume that's all homebrew and perhaps vermi-crete (havent read the thread, but I will) Nice reuse of the existing molds. We went the easy route and bought a ready-made, I am too scared of working with natural gas or propane.

    We made lots of progress this weekend. Got the 800F drying fire done on Friday morning, and the dome cleared rather nicely! (making lots of black smoke)

    We took the opportunity to make Focaccia and Pizzas Friday eveming (focaccia first - to test oven) The floor was still a little cool, so we pulled the focaccia in after 4 minutes and it was delicious, if a little light in color. Then we made 4 Pizzas and they all turned out great, the last couple were a little hotter, and managing 2 pizzas in the oven was a bit trickier, but we got the golden crust we wanted in about one minute! (maybe too quick?) I think with me working the oven - between 700F to 800F will be the best compromise of speed and workability.

    Click image for larger version  Name:	First Focaccia.jpg Views:	0 Size:	268.7 KB ID:	449750 Click image for larger version  Name:	Working the oven.jpg Views:	0 Size:	405.7 KB ID:	449751 Click image for larger version  Name:	Focaccia Bubbling away.jpg Views:	0 Size:	301.8 KB ID:	449752 Click image for larger version  Name:	Focaccia Done!.jpg Views:	0 Size:	182.2 KB ID:	449749

    Roasted Garden Tomatoes, Salami and Burrata on the left - Chicken Italian Sausage with Pesto and Sauteed Purple Onions on the right.

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    Last edited by Sixto; 09-19-2022, 12:16 PM.

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  • david s
    replied
    Originally posted by Sixto View Post

    Yes, the diversity and depth of knowledge of FB Forum members are just a few of the things that makes it so helpful! Of course, my wife thinks she's the expert with any cooking or fire-related activities in our house.

    Dome is starting to clear! Quite a bit hotter fire today... too hot to get my hand inside the dome without welding gloves!

    Finally, a photo of my wife in front of her gas kiln - she's firing to 2300F today, so my little 820F Pizza Oven is just a toy to her (but a big deal to me!)

    Very nice. You may be interested in my gas fired kiln, which I used my pizza oven moulds to make part of it.

    https://community.fornobravo.com/for...608#post446608

    Leave a comment:


  • Sixto
    replied
    Originally posted by UtahBeehiver View Post
    In addition to being our cast expert, David S is also a ceramics and pottery expert as well (gas fired kilns),
    Yes, the diversity and depth of knowledge of FB Forum members are just a few of the things that makes it so helpful! Of course, my wife thinks she's the expert with any cooking or fire-related activities in our house.

    Dome is starting to clear! Quite a bit hotter fire today... too hot to get my hand inside the dome without welding gloves!

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    Finally, a photo of my wife in front of her gas kiln - she's firing to 2300F today, so my little 820F Pizza Oven is just a toy to her (but a big deal to me!)

    Click image for larger version

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  • UtahBeehiver
    replied
    In addition to being our cast expert, David S is also a ceramics and pottery expert as well (gas fired kilns),

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  • Sixto
    replied
    Originally posted by david s View Post
    Be careful with the construction of such a door. Others have built similar and the reduced air intake makes the fuel:air mixture more like the ideal. (search "blast door") This results in the fire starting to roar. We used to do this trick to our fireplace as a kid, holding a large sheet of newspaper across the fireplace mouth allowing a limited airspace at the bottom. The problem is that the fuel content is so hard to control with wood, that the fire roars away forcing a heat rise that's way too fast for the dense oven to cope with. It is the equivalent of firing a kiln at full blast from ambient, something a potter would never do. As the oven is particularly vulnerable when it still contains moisture this practice could end up doing irreparable damage to your oven.
    Once your oven is dry the smoke issue should disappear.
    Thanks David! I totally agree, I still like playing with my fireplace doors too to get the fire roaring when I start it. I will be careful going forward. When I first tried it yesterday, I noticed my fire wasn't big enough to significantly restrict the intake air, which was fine. I will get there eventually, but even then I will only close the "blast dooor" for a short time, keeping a watchful eye on the fire and the temps during that time to ensure things don't get out of hand too fast. I now know how quickly that can happen!

    Good timing also, my wife is firing her gas kiln today for only the 5th time since we got it.... still learning a lot about that too.
    Last edited by Sixto; 09-16-2022, 05:51 AM.

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  • Sixto
    replied
    Originally posted by MarkJerling View Post
    When your construction is still quite wet, 700F may not be hot enough to burn off soot. Once it gets to 900F the soot will be gone.
    I do like your flue modification! Might try something like that myself!
    Not only will we have the new term "a Sixto landing" but also "a Sixto flue"!!!
    kk

    Thanks Mark! its fun to try new things, and learn from them whether they work or not. I might try to squeeze in a Pizza or TWO? between the next drying fire and the stucco render on the dome....it all depends on the weather.

    Leave a comment:


  • david s
    replied
    Be careful with the construction of such a door. Others have built similar and the reduced air intake makes the fuel:air mixture more like the ideal. (search "blast door") This results in the fire starting to roar. We used to do this trick to our fireplace as a kid, holding a large sheet of newspaper across the fireplace mouth allowing a limited airspace at the bottom. The problem is that the fuel content is so hard to control with wood, that the fire roars away forcing a heat rise that's way too fast for the dense oven to cope with. It is the equivalent of firing a kiln at full blast from ambient, something a potter would never do. As the oven is particularly vulnerable when it still contains moisture this practice could end up doing irreparable damage to your oven.
    Once your oven is dry the smoke issue should disappear.

    Leave a comment:


  • MarkJerling
    replied
    When your construction is still quite wet, 700F may not be hot enough to burn off soot. Once it gets to 900F the soot will be gone.

    I do like your flue modification! Might try something like that myself!

    Not only will we have the new term "a Sixto landing" but also "a Sixto flue"!!!
    Last edited by MarkJerling; 09-15-2022, 08:55 PM.

    Leave a comment:


  • Sixto
    replied
    Originally posted by UtahBeehiver View Post
    Gulf and I have notice that there is a unique smell as the carbon burns off and dome is clearing.
    Maybe my thermometer is off? I got up to 700F plus, within 30 degrees across the entire top of the dome, and the soot still has not burned off.... at the very end of the heating-up phase there were a few lighter spots directly above the coals... but who knows... We'll see what 800 degrees looks like tomorrow.

    Click image for larger version  Name:	Firestart 7 - Day 6 - 701.jpg Views:	0 Size:	130.1 KB ID:	449663
    I also tried two new experiments today and they were both resounding successes:

    1) I built a smoke diverter using the plywood forms I had made to hold the dome arch while mortaring - yes, the wood charred, but still proved the concept works. (The idea being that since my gallery is so large, the smoke doesn't always go straight-up the flue, depending on what the wind is doing)

    To make it, I purchased a black steel elbow and an 8" straight section of 6" diameter flue pipe from the local Builder's supply store, cut an oval shaped hole at the top of the arch forms to insert the pipe snugly, and cut a rectangular slot at the bottom. In my case, the rectangle is 2.75" tall x 12" wide. and screwed two handles on to the plywood. The whole thing goes on and off easily, and fits nicely within the dome arch opening. The bottom rectangular slot provides enough combustion air flow to keep the fire going strong. The two flue pipe sections do a great job of getting the smoke from the top of the arch to the flue, and out of my eyes. I only use the diverter until the wood stops smoking after about 10 minutes, then I set it aside. I will eventually rebuild with a stainless plate.

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    2) I found a rusty old grate that is fairly light-weight from my fire-pit that is perfect to set the coals on, and move around the dome by picking it up with my turning peel to get an even temperature all around the dome. This is more efficient and more effective than my previous approach of building multiple smaller fires around the dome. It also made the wood burn a little faster, and the floor got warmer all around the grate.

    Click image for larger version  Name:	Coal Grate on Day 6.jpg Views:	0 Size:	286.0 KB ID:	449665
    Last edited by Sixto; 09-15-2022, 08:09 AM.

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  • UtahBeehiver
    replied
    Gulf and I have notice that there is a unique smell as the carbon burns off and dome is clearing.

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  • Sixto
    replied
    FIRE IN THE HOLE DAY 6 - Goal is 600F

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    A bigger, hotter fire, started by spreading charcoal in 3 areas along the back of the dome, and adding sticks gradually until I reached 600F at the apex of the dome. This gave me a nice, even distribution, and an easier way to control the temperature climb. Still, it takes a while to soak the dome evenly (about 90 minutes fussing with the fire)...at the point the photo was taken, I had consolidated all the embers on the left side, and the apex of the dome, plus the entire right side of the dome was around 480F, and the floor was about 310F.

    I'm not too concerned that some areas were hotter than 600, since I had already (accidentally and momentarily) reached this temperature 2 days ago. I was more concerned with minimizing the temperature variation across the entire dome, not having a huge hot-spot, and controlling the overall rate of climb.

    There are NO areas where the soot is clearing out completely yet... I'm expecting to reach that tomorrow, at least in part of the dome, when I get to 700F. If you look carefully at the bottom edge of the dome arch, it's a little lighter than the top of the arch, but not much...

    Every day I get more of a feel for how the oven works, so I think there is as much value in using the drying fires as a learning opportunity, as it is a way to gradually dry the dome bricks and perlcrete layer. The perlcrete got a little hotter all around - about 110f. Ambient temperature was around 70F.

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  • Sixto
    replied
    FIRES in the Hole! - Day 4 - goal is 500F

    Today it was a much more controlled climb, I got just around 500F in about one hour, split the coals into two groups: left-rear and right-rear, and slowly added single pieces of kindling (1 at a time every 3-5 minutes).

    A few observations: I tried to throttle down the arch opening with a few bricks, mostly to see if I could get the smoke out of my eyes - but noticed the fire got smokier when I did that (which I'm interpreting as less efficient burn, not enough oxygen to fully burn the secondary combustion gases) When I opened it up, the smoke cleared, the fire got visibly more active, and temperature climbed.

    This time I also noticed the walls below the dome apex were about 50F cooler than the apex... (vs 100F to 150F cooler) and also the floor was warmer than yesterday. I think this is partly due to the distribution of fire into two areas vs one, and the additional amount of time the fire had to soak the dome bricks. Remember that yesterday my goal was 400F, but I accidentally got to 600F. Yesterday's fire was both quicker and more concentrated at the center.

    Finally, I noticed the fire got a little bit hotter when all of the sticks became embers, something to think about when building up the temp... a flaming stick produces light and heat; a glowing ember gives off less light, but perhaps more heat? This time I'm letting the fire die down naturally instead of bricking up the archway.

    The crack is still there, but bothers me less already. I don't know how far up the dome it goes... It was narrower when I started, then it opened back to 1mm while I got the oven up to temp. I'm starting to see it as a sign of the oven's character insted of my stupidity, sort of like Harry Potter's lightning-bolt scar. I guess we never know what we don't know until we try to do something! (even when we're repeatedly told what's likely to happen - heh, heh)

    Click image for larger version  Name:	Firestart 6 - Day 4 - 498f.jpg Views:	0 Size:	458.7 KB ID:	449612
    Last edited by Sixto; 09-13-2022, 12:40 PM.

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  • Sixto
    replied
    Thanks Russell and MarkI believe you, but I wish I had of those "invisible cracks" that some ovens get...
    I will get over my disappointment tomorrow, and build even slower, more distributed fires for the rest of the week.
    Even though it got as high as 600F today, i will also stick to the schedule and try to stay close to 500f tomorrow.
    Last edited by Sixto; 09-13-2022, 05:54 AM.

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  • MarkJerling
    replied
    Yup. there are two types of ovens: Those with cracks and those who's owners can't see the cracks. Don't sweat it Sixto

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