Sleuthing the stone
When baking two bâtards or a few baguettes, I've noticed of late the bottom of the bread closest to the left side of my stone is much darker than the others. Almost black in a few spots, as if it was charred.
I have a natural gas oven, 14" x 16" x .5" stone (which is clean and in good shape), and have an oven thermometer on each side of of the stone. The thermometers read the same temperature, be it 500F or 460F. There's always a sheet of parchment between the bread and the stone.
When I steam my oven, I use ice cubes in a loaf pan with lava rocks on the left side of the oven and a broiler pan filled with lava rocks on the right side of the oven. I wondered if my new steaming method is having something to do with the excessive coloring on the left side. However, I get the same darkness on the bagel bottoms that sit at the top left side of the stone - and bagels aren't steamed. Actually, the steam pans are removed when I bake bagels.
No issues when I have just one bâtard or boule in the oven - but then, it's generally in the center of the stone.
Any ideas?
Thanks.
I don't understand what science is being applied with the ice cube/lava rock thing, but I doubt is has any affect on what you describe.
Best guess is that the density of your stone is inconsistent, creating hot spots.
I wonder if as the stone ages, the density would change. The darker color in portions of the crust bottom is something new. Same Hamelman sourdough formula, though.
Guess I better pay more attention to where the dough is sitting next time, to see if I can pinpoint the area.
I would agree that you have uneven density in your baking stone, creating an overly hot spot. Air circulation in the oven during baking might also be an issue; I have an electric oven and notice that the loaves toward the back (or the loaves' sides facing the back) brown faster. I rotate my loaves about halfway through the backing round and this helps.
What could have changed recently (even things that don't seem related:-)? Take the stone out to clean it and put it back ...but not in exactly the same spot? Catch the stone badly with the peel, or otherwise bump it right up against a wall of the oven? Move a rack up or down? Add or replace some sort of spill shield? Shift steam generation apparatus?
And could there be anything odd about the heat flow? Trouble turning on the oven? A sudden change in your monthly gas bill? Some parts of the flame have a much harder time starting than others? Flame light doesn't look even? Overall temperature calibration seems to have changed?
(I'm not suprised at what you seem to have discovered: oven hot spots are often too weird to be diagnosed with thermometers.)
That's about all that's changed, Chuck. I moved the stone one inch towards the right side of the oven. No change in position of oven racks.
Stove and oven work fine, my natural gas usage is so low I get billed every two months instead of monthly (I heat my home with wood).
I don't think density comes into play. The only way the density of an object can be changed is by changing its shape. The stone is still the same shape. No cracks, no bumps or thumps.
If it's a hot spot, then it's developed within the last month. I'll be doing bagels in a couple days so I'll pull out both steaming pans to see if maybe their position on the bottom rack is having some effect. If that's not it, then I'll try rotating the stone.
Something has changed. Maybe I can track it down through a process of elimination.
Hmmm.
My first guess is your steam apparatus. (You said there was no hot spot when you were making bagels with the steam apparatus taken out of the oven. That sounds like it might be a big clue.) [Edit a few hours later: I realize now I interpreted the bagel example backward, that the "hot spot" existed even when the steam apparatus was removed, so this whole first guess is quite unlikely.]
Maybe too much surface area of the bottom of your oven is covered. Maybe the broiler pan is too thick and large, so heat doesn't penetrate it very well, so a cool spot has developed above the broiler pan ...which looks like a hot spot on the other side.
What about using two loaf pans, one on each side, rather than a loaf pan and a broiler pan? Or what about moving the steam apparatus up to the lowest rack rather than right on the bottom of the oven. Or what about putting some extra metal (finishing nails work well) in the bottom of the steam pan to absorb and hold more heat while taking up less surface area? Or what about jiggling the steam apparatus around just a little to make sure it can't touch any of the oven walls?
And my second guess would be that "one inch to the right" pushed your stone so close to the edge (especially combined with the steam apparatus) that air can't circulate freely between above and below any more.
I started to respond to your bagel hot spot comment last night, then got called away from the computer. Not surprising you caught and fixed it, given your attention to detail.
On to the oven: I have two oven racks. One holds the stone; the lower rack holds the steam pans. Nothing can be placed on the floor of the oven because the manual has dire warnings about the evil things that can happen if the openings in the oven floor are blocked. I tend to heed manufacturer warnings.
After reading your comments about the broiler pan and air circulation, I took some measurements. There's 3.5 inches between the stone and the back oven wall and plenty of space between the stone and the side walls. The loaf pan on the left is is centered between front and back (but not touching the wall) but I noticed the broiler pan on the left was pushed in so far that it was flush with the back wall of the oven. Since the heat comes from the bottom, could be that broiler pan location is having some effect. It's been moved.
If that's not it, the broiler pan will be replaced with another loaf pan for my ice-cube melting/steaming gizmo and I may even rotate the stone.
Thanks for the suggestions.
You're familiar with the way water goes down the drain, clockwise or counter-clockwise? Would steam also be influenced this way in how it swirls in the oven? Creating hot or cool spots? Would if matter if you were in the northern or southern hemisphere which side was affected most?
I wondered about that MiniO, but as noted, the same excessive browning happens when I don't steam.
It sure would be fun to be insert colored smoke into an oven and watch the pattern of the heat currents and where they exhaust.
The job of steam in the oven is to humidify the air. Without some outside influence, the steam will essentially distribute itself relatively evenly throughout the compartment.