Does too much flour on the surface of a loaf dry it out and prevent oven spring?
So far answer is... it depends.
Depends on the amount, how long, type of flour, method, dough moisture, ambient humidity, score plan, to name a few variables. Is a banneton, basket or cloth lined bowl involved? Is the dough covered and with what?
Generally grain flour will pull moisture to it away from the surface drying the "skin" of the dough. Spring has to do with the dough expanding under the skin when heated, testing any surface tension existing at the time. Too thick or strong surface tension could prevent oven spring. It is however rare that the whole surface will be equally strong and thick enough to hold in all expansion and the weakest spots will rip open as steam escapes the dough during baking.
Then a tough skin shouldn't matter so much... right?
The trick is to score a thick crust so the dough springs where you want it to go. The tough surface can be scored so that bands of surface dough hold the basic shape while dough expands between forcing the cuts open or tear when stretched too far. That can make some neat looking loaves! Shaping the dough, creating an inside "grain" and tension inside the loaf can add to the dynamics of the spring opening. Scoring will have varied effects whether a cut is made across or with the "grain" of the dough. There is a lot of fun to be had there!
One can score one big score the length of the loaf or try multiple scores. If you cut enough tiny scores you can have as much expansion as a big one. Sometimes I like to look at the skin of a loaf as a net. How many cuts can I make without connecting the cuts to each other?
Don't be afraid to try different tools to cut. Try scissors, cutting wheels and sharp edged cookie cutters. If you have a really tough skin on the dough, do cut down deep enough to reach the soft stuff underneath. Then next time protect the surface from drying out so much.
Thank you! I haven't been thinking about how the direction of scoring relative to the grain might matter, but of course it does. I also haven't been very conscious of how I fold the dough and how that organizes the gluten network within. Now I know better what to think in terms of, and what the end goal is, when I shape my dough.
To answer your earlier question I was proofing my boule (500g flour total: 10% whole wheat, 30% bread flour, 15% flour from starter, 45% AP at a total 76% hydration) at 74F in a cloth-lined bowl covered with the ends of the same cloth.