Need some bread bakers advice
I am trying to make bread using a banneton. I am using a recipe from "Bread" by Jeffrey Hamalman. The dough feels right and I follow directions. It rises in the banneton and then I flip it onto the peel and slide it into the oven. That's when it goes wrong. It spreads out and goes from about 5 inches high to about 2-3. It bakes well and when it's done you can feel the heaviness on the bottom. I am using King Arthur Bread Flour. Do I need to try adding vital wheat gluten? How much per #1 of flour. Or maybe I am missing something. Pleas Help! The design on the top is great but.....
My first guess would be over-proofed. Dough adapts to its surroundings. Even a few more degrees, some extra humidity can proof it up earlier than you think.
My second guess would be that you need practice in the technique. You have to make the exchange carefully, lightly. Its like rolling a ball over, not flipping it. I've botched it many times, especially if the dough is a bit over-proofed anyway.
I think there are videos of how to make the transfer, at least I know freshloaf has some board transfers and things like that. Hopefully it will be helpful until you figure out your own style.
That sounds to me like you have not developed the gluten structure, so yes, the Vital Gluten from King Arthur, would be helpful.
I'd also look at kneading for a longer time.
Are you aware of what the firmness of the dough should feel like before the second rise?
Do you know what a tight gluten cloak feels like?
Once you've felt it, you know it. And, I'm sorry, it's a bit
impossible to describe -- soft but with a firm structure -- and unless the gluten structure is developed, your bread will spread as you describe.
Are You stretching and shaping the skin enough? I watched a few videos of Julia and others shaping baguettes and they stretch it about three or four times to get the shape right. My guess is that you need a strong skin just before you set it into the mold so that it can form the indents but still retain its shape
In addition to the other suggestions, I wonder if the moisture might be a touch higher than needed. But the heaviness on the bottom suggest an anomalous rising pattern: too liitle kneading and gluten formation. I wouldn't think extra gluten should be called for in a King Arthur White Bread Flour.