White "cooked" flour coating

Hi all,
I have 2 cane bannetons with linen liners. When making sourdough, I flour the linen liners liberally so the soft dough does not stick. However, after baking the loaves, they have a coating of cooked flour. If I use less flour in the banneton, the dough sticks to the linen. How do I eliminate this "white" coating of flour on my sourdough loaves?