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Tall fire, yes. Wide fire too.

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  • Tall fire, yes. Wide fire too.

    This may have shown up somewhere before but I haven't seen it. This is not a question so much as a discussion.

    I have a 42" Pompeii. When I build a fire in it I have learned that I need a fire large in area. Tall and lapping the inner dome, yes. But also a fire which covers much of the floor. This seems the best way to get the dome all white as otherwise, with a smaller fire, I only get part of the dome to go white. Which also has an effect on the hearth heat. With my fire covering much of the hearth surface, and large and rolling along the inner dome, the white comes on evenly distributed. Prior to doing this I simply built a tall and very hot fire mostly in the center (until pizza time, that is.) My fires were good sized to a point but I found I really needed to spread and broaden the fire along the surface. I am supposing this is a character of oven size. I don't recall seeing any discussion on how large the area of a fire should be in relation to oven diameter. Just that it is important to build, and how to build, a hot fire which laps along the inner dome, turns the brick white, and gets moved to the side for pizza, and out altogether for bread. Now I essentially build a first fire and then I expand it so that in a sense I have built a few different smaller fires, all allowed to join up and expand the others. The point is to create a raging inferno with a series of tall flames covering the entire inner dome, flames which mostly only have to go up to do the job, because there is enough flame all over which can take on the task of hitting the entire dome surface, so that no one flame has to do all the heavy lifting by traveling from one wall to the opposite wall via a trip up and over the dome. So, rather than attempt to have a vigorous tough-guy fire in the center doing its best to spread out over a 42" oven, I have five fires, more or less front, back, left, right and center, all converging into one hell of a blaster.

  • #2
    Re: Tall fire, yes. Wide fire too.

    Hi Kim!

    This is the kind of discussion where I think words tend to display their fuzzy. My small fire may be you large one, or vica versa and pictures say much more than words...

    Directionally you want to have coals all over the floor to heat the hearth. There is a complication though in that ash is highly insulating. As a result you probably don't get full benefit of a fire covering the whole floor. Probably better to have one hot/intense fire in the front center to begin the process of warming the floor and then pushing it (and the coals) to the back and sides and adding wood more or less around the perimeter. I find that works well and is fast. And it charges the hearth well which is one of my weak points since my insulation is below my hearth slab (ala Alan Scott). However...

    Your suggestion is an interesting one. I would think you could omit the center fire and simply rake coals to the center to charge the hearth. The flames on the sides should do a good job of heating the top of the dome without having flames directly below...

    Interesting question!
    Jay

    Comment


    • #3
      Re: Tall fire, yes. Wide fire too.

      Hello again, Jay,
      I think you are right to point out the insulating nature of the ash, and the resultant difficulty of heating the hearth, which has also been a difficulty for me. And I like the idea of perimeter fires. I think this addresses exactly what I am learning. I had been having slight failures recently - mostly having to do with a too cool hearth - and when making bread I have reduced how much I bake each time so that the failure will result only in a minimum of waste. Which means we run out of bread sooner and I have to bake again sooner. Which is actually a good thing as it provides more opportunity to learn. So, fortunately, though I baked yesterday, I think I will again on Thursday. I look forward to trying the perimeter fires. Hell, I almost feel like running out there and building a fire with nothing to bake. I will resit the temptation though.
      Thanks for the input, Jay. Invaluable as ever.
      Kim

      Here's a photo of yesterday's bread, just to show off. It's the Country Genzano from Dan Leader's "Local Breads" (a title which at first confused me in part because I live local to Dan Leader.)
      Attached Files
      Last edited by KEmerson; 11-29-2010, 06:18 AM.

      Comment


      • #4
        Re: Tall fire, yes. Wide fire too.

        I think you may be on to something there. I am just now exploring heat management in my 42 oven, and have noticed that the area where I build the fire , whether directly in front of the inner arch or more centered in the oven, that the hearth where the fire is built seems to retain that heat rather well for later cooking, but 8 or so inches away seems to be a good deal cooler. I almost think that I should be heating the area where I plan to cook for a while then move to the side. My pushing of the coals to the side invariably results in some on the back wall, and I get nervous when the metal peel doesn't get a good clean slide under the pizza, but pushes it back to the ash or coals. I am going to try to push it much more to the side so that if it pushes the pizza back at least that area will be clean.

        Comment


        • #5
          Re: Tall fire, yes. Wide fire too.

          Beautiful loaves, Kimemerson. I'm having trouble getting my oven temp down to good bread baking temperature. I usually build a very hot fire for pizza, then, after the pizza, shut the door to let things settle down and the fire die out, then remove the fire, swab and leave the door off to cool it down. But, I've been scorching the loaves. Bread I'd bake as hot as my kitchen oven goes (about 500) scorches if the door thermometer on the WFO is at 500 or a little higher. Any suggestions would be appreciated. Your loaves look perfect.

          Karl

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          • #6
            Re: Tall fire, yes. Wide fire too.

            I seem to recall reading of an initial heating fire technique somewhere on the FB site where the chef made a 'ring' of logs inside the perimeter of his oven that stacked up like leaning dominoes. He would light the left end of this ring and the fire would slowly burn to the right. When it was burned down to coals his oven was golden.

            Comment


            • #7
              Re: Tall fire, yes. Wide fire too.

              I move my fire around. First in the middle then towards the back then the right side and finally to the left where I leave the coals to cook my pizza.

              Heat from the fire is largely released in heated gas plasma (the red and yellow flames). This rises and radiates largely heating the dome. I think most floor heating comes from heat that is re-radiated from the dome back to the floor.

              It would be fun to measure the weight of wood and time used to heat the oven with different firing techniques. My guess is the fastest is not the most efficient.
              My oven build: http://www.fornobravo.com/forum/f8/m...and-13300.html

              Comment


              • #8
                Re: Tall fire, yes. Wide fire too.

                Hi Kim!

                How much bread are you baking at a time? Looks like a fair amount. I find it takes about 15 pounds for me to get a great crust in my 39 inch WFO. Less and the color goes downhill. Your color looks pretty good. A problem with smaller bakes in the WFO is that the bread color and oven spring can easily decline with the lower humidity. There are workarounds - at least of sorts but... In any event, nice job.

                As a more general comment to everyone, one can do pizza even before the dome clears. I don't recommend it, but one could pretty well heat up the hearth and have flames to broil the top in a "fast" (quickly warmed/heated) oven. I can do that it about 30/40 minutes and am clear in well under an hour. I have found, however that going about an hour 15 gives me better heat loading and more consistent pizza results. Bread needs more heat loading. You really need to push some heat into the refractory for it is that heat that bakes your bread. You probably need at least an hour 30 or so in a well insulated oven. I go for about 2 to 2:30. Timing putting the bread is is tricky unless you have an infrared thermometer. The oven door thermometer is likely useless. Getting the bread and the oven at the optimal point at the same time is an art and why really great WFO bread is so highly revered. The oven should be cleaned out while hot and closed and allowed to heat soak/equalize. The hearth temp will probably be about 30 to 50 degrees warmer than the dome. You typically want to put artisanal sourdough boules and such in the oven when the hearth hits 565 or so. One loaf won't work at that temp. You need enough bread to knock the temp down, humidify the oven, and the bread bakes as the oven "reheats" from the heat stored in the refractory.

                Hope that is useful!
                Jay

                Comment


                • #9
                  Re: Tall fire, yes. Wide fire too.

                  Jay,

                  Yes, it was most helpful, thank you for sharing your expertise. I would much like to see how you load your 39" oven since that is the size of my in-progress Pompeii. I'm also wondering how difficult it's going to be to regulate the relative temperatures of my firebrick dome and soapstone floor. I'm planning on following your process of cleaning the oven and letting it equalize to 565F. If the soapstone scorches the bread bottoms as mentioned by Scott/Wing in the Bread Builders, I guess I'll have to swab the floor a few times to get it down to 565F given a 30-50F variance.

                  Does spraying the tops of one's loaves prior to oven entry sound practical?

                  Thanks in advance,

                  John

                  Comment


                  • #10
                    Re: Tall fire, yes. Wide fire too.

                    Jay,
                    That load was only about 7.5 pounds. You can't see by that photo but the bread had great top rise but the bottom was slower to bake and has much less rise to it. It was in trying to get the bottom to cook that the tops browned so nicely. I had the oven up to the high 500° range but I know the hearth was too cool. I am still working on getting a nice dome/hearth balance and most common for me is the cool hearth. Which is the reason for a few of my posts here. But his one was admittedly better. You mention "heat loading" in your post. What is that? I could venture a good guess but I'll wait. It seems to be something I need to know.

                    John: I spray/mist my breads once they are all loaded and just before I close the door.

                    Here is a pic of the bread sliced. I made larger boules as well as smaller rolls, which were actually too large to ever be called small.
                    Attached Files

                    Comment


                    • #11
                      Re: Tall fire, yes. Wide fire too.

                      Hi John/Kim!

                      By heat load I mean extending the burn to push heat into the refractory and cladding so that there is heat available in the mass of the oven to "ooze" back to the oven and bake the bread. If you only heat the oven until the surface is at temp you will chill the oven with the dough (and open door) and it won't bounce back to the temp you want for baking.

                      You got great color for only 7.5 pounds of dough Kim. Nicely moist oven. There IS a balance between the amount of bread you bake and the amount of dough you put in the oven. (And every oven is a bit different!) Example: One loaf would barely cool the oven and would burn at 565. A full load (say 15 pounds) will probably knock the temp of the air in the oven well below 200 and the hearth to near 212 at the surface where the loaves are and 300 to 350 (maybe 400) where it is bare. The dome will drop somewhat but not so much. It is the heat you loaded into the refractory that somewhat gradually heats the oven back up to baking temp around 450 when the loaves are done. Then when you take those loaves out the oven SHOULD heat on up to over 500 or so (ideally 525 to 550 in an AS oven) so you can do a second load (of different breads for the temp won't be as hot). IF you are only doing one load this is obviously les significant but if your oven doesn't heat up after you remove the bread it wasn't very well heat loaded and your bake is probably impaired.

                      Swabbing before loading the bread is always good for it helps increase humidity. I don't personally recommend spraying artisanal loaves so I try not to spray directly on them though I do spray up into the dome...

                      The challenge John with the soapstone hearth is that it tends to conduct heat faster than refractory so the bottoms can scorch. You may need to use a somewhat lower hearth temp - perhaps even 500 or so and even that depends on the dough load in the oven. The dome/hearth balance is not easily managed. It will be what it will be. You just have to find the temp that gives you the results you want. As indicated before, getting sourdough and oven to peak at the same time takes some experience and practice. Consider doing yeasted breads at first to simplify the timing for they will be much more predictable!

                      Good Luck!
                      Jay

                      Comment


                      • #12
                        Re: Tall fire, yes. Wide fire too.

                        Hello Jay,
                        You know, I sort of knew that's what heat loading is. And I don't remember my coming across any mention or discussion on it which might be why I had for a while assumed that getting to pizza hot was enough, and that once that was hit it was ok to stop firing. But logic eventually told me about heat loading without knowing it had a name or that I was even right. And I've only just recently put it together so that and the perimeter fire/hearth heating issues has me feeling better about the next firing/bake (Saturday? Weather permitting).

                        Your example description of the oven cooling too much and too far and unable to recover in a poorly or insufficiently heat loaded oven makes me ask if you weren't looking over my shoulder recently, like, maybe you were sort of peeking over the neighbor's fence or something. Because you have my experience down almost to a degree. I think I'm gong to print this page and staple it to my forehead till I get this down. Thanks.
                        Kim

                        Comment


                        • #13
                          Re: Tall fire, yes. Wide fire too.

                          Hi Kim!

                          More like the voice of experience and recognizing myself and my errors in your description!

                          I think many of us get infatuated with the get it fired and ready along with a "save the planet and/or our wallet" by not burning extra wood so we creep toward shorter heating periods. And for pizza with a well insulated Pompeii that probably works. My slab is an AS design with 5 inches of cement with insulation below and it takes about an hour and a half to charge it fully for pizza and longer for bread. If I heat for an hour it will slowly cool as I do pizza and I will have to rake coals out and recharge the surface about every half hour if I want really perfect crust. After an hour and a half or so or heating the radiant heat from the dome keeps the hearth hot (so long as I keep flames) and it doesn't ever seem to need recharging.

                          Your bread looked quite nice. One of my "tricks" to get better crust is to make a batch of ciabatta and bake it with my loaves. I do the ciabatta around 85% hydration and it is wet enough to really add humidity to the oven!

                          Hang in there. You WILL work out the kinks!

                          PS: as a stupid example (but I love stupid example) of the importance of heat loading....
                          Imagine you want to cook a steak. You can heat a cast iron skillet in the WFO to say 600 all the way through and throw a steak on it and it will char the outside of the steak to a beautiful crust. (Might or might not do the other side but...hang with me). I could heat a sheet of aluminum foil to 600 and throw the steak on the foil and it would barely do anything to the steak. The foil would have temperature but not the "heat" storage to heat up the steak. A quick heat versus a thorough one is a bit like aluminum foil versus a cast iron skillet. We have to put the heat into the oven before we can use it!

                          Keep baking! You are on a good path!
                          Jay

                          Comment


                          • #14
                            Re: Tall fire, yes. Wide fire too.

                            Jay,

                            Thanks profusely for the words of wisdom and experience. I understand the concept of heat loading (brick-charging?) but had no idea the oven floor could be that dynamic. It now makes a ton of sense that the only way to get to know one's ideal oven equilibrium is through testing. Knowing upfront that soapstone transmits heat at a slightly higher rate than brick (I learned this from IR-ing a sun-baked soapstone slab right next to a firebrick) hopefully means that if I start from a relatively lower temp, I can load my bread, suck out some of the floor heat and utilize the residual heat from the 2.5" of fully-loaded firebricks below while not scorching the bottom of the bread. I'm wondering though, what effect does a higher hydration have on the ability to reduce scorching vs the quality of the bread?

                            Again, this is one trial-and-error opportunity I am willing to tackle, but have to finish my oven first.

                            Great analogy with the foil and cast iron skillet. Even I get it!

                            John

                            Comment


                            • #15
                              Re: Tall fire, yes. Wide fire too.

                              Hi John!

                              The soapstone will not be a problem. You will just wind up with slightly different baking temp/time than if it were refractory. Big deal! (Totally unimportant!)

                              In my experience dough hydration has no impact on browning or scorching on bread dough that I can attribute to hydration. I can theorize that it might in pizza, but the water content diff of a 200 gram ball of 60 and 70% pizza dough is only 7.35 grams of water (out of about 75 to 80 grams or 10%), (about half a tablespoon!) and that is spread out over about 75 square inches of pizza so there isn't much water diff and the hearth temp can vary a lot so....I think scorching is likely to be more a function of hearth temp than dough hydration. BTW, I used the 200 gram ball just for simplicity of calculations.

                              Good question! And glad you enjoyed the foil!
                              Jay

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