Baguette Burnt on the Underside

A photo of your problem loaves would help. Here are some questions to answer, so you get an appropriate solution:

1. How much do your baguettes weigh, and how long are they?

2. Besides the bottoms, do you feel the rest of the crust's coloration is just right?

3. What kind of oven do you have (gas or electric? heats from top, bottom, both? convection?)

4. Have you checked to see if your oven is heating to the temperature at which you are setting it?

As a possible shortcut, if everything else is perfect except for the bottom crust being too dark, put some parchment with cornmeal or semolina on it between your tiles and breads. You might want to try baking with the rack farther from the heat source. If the top crust is too dark too, bake at a lower temperature. 

I'm sure we can help you.

David

Preheat to a lower temperature.

The proper temperature is a trial and error thing. If you want to see an immediate improvement, lower it to 450. If the bottom is too pale, split the difference.

(BTW, if, during preheating, the top element is coming on, perhaps the tiles are getting too hot because they're so high in the oven and close to the heating element. Personally, I don't bake anything in the top 1/3 Anyway, lowering the rack might could help in this instance. Just speculating here.)

Hi David (again),

• Baking temp is too high
• I keep my baking deck as close to the lower element as possible, only the steaming trays are lower.  I also have an electric oven with the lower element doing the labor.  Once before I showed you that the bottom of my baguettes never (really never) burn.
• Try not using convection mode (I never do), but if you do, only in the second half of the bake and then lower the oven temp.
• The additional 10 minutes to vent is way more than I've ever done, regardless of whether it was baguettes or batards.  A typical venting period might be 1 to 3 minutes tops.
• If you use parchment, you don't need another layer of anything below the baguettes i.e. cornmeal, etc.  The parchment acts as an insulator between the dough and the tile deck.
• I use 2 cups of near boiling water on lava rocks just after loading the dough.  This ensures that there will be sufficient steam throughout the first half of the bake.  You might want to increase how much water you add.
• How long to bake?  That's a trial and error deal.  Visual familiarity with what your bread should look like as it nears the completion of baking is a learned experience.
• Even a correctly calibrated oven will yield hot and cool spots across the baking tile.  For instance, the deck directly above my lava rock pan is cooler than the rest of the deck by tens of degrees.
• Therefore when you release the steam swap positions of the baguettes on the deck, both left to right as well as rotating them front to back.
• Keep the dough as far apart from each other as possible, as the dough itself will keep its neighboring doughs cooler or you'll have less baked sidewalls to your bread.
• When you swap positions try to change which doughs will be near to the oven wall without a neighboring dough (see above).
• Do the above in a late stage of baking as well, even during oven venting at the end may bring a benefit.
• If your oven does not cycle into recovery mode soon enough, force it to.  As soon as the steam is introduced, it will drop the oven temp due to the much cooler steam, as well as the cool dough being loaded into the oven.  Whenever you open the oven door, the temp inside will start dropping immediately.

Try some/none/all of these things and take notes, mental or written, on what changes you experience.  And most importantly - don't forget to boogie!

alan

It probably is a matter of successive approximations. I bake my demibaguettes at 480dF, but I scale them to about 250g, and I like them dark. If you are scaling at 325g, those are near full-size. A 350g baguette is often baked at 340-350dF for 22-25 minutes, but they traditionally have a paler crust than what I prefer. I think tgrayson's advice to bake at 350dF and raise the temp if the bake is too light or takes too long. 

Again, what I was taught is that full-size baguettes should bake in 22-25 minutes, and you set your oven to give you that result.

Experiment with pre-heating temperature too. I think 20-25dF hotter than your planned baking temperature is reasonable.

I don't have any rules of thumb for venting times in a home oven. In general, the wetter the dough and the heavier the loaf, the longer the venting (oven off, door cracked). So, for a 80% hydration, 2kg miche, a 30-60 minute venting is reasonable. I don't do it with baguettes at all.

David