Add the all-purpose flour and bread flour. Food Science Lesson #2: Why the bread flour (this also answers the why knead the dough)? Bread needs the flour protein, called gluten, to rise up light and stay that way. Gluten when developed, forms longs elastic strings. These strings, because they are elastic allow them to stretch when the yeast does its job. Bread flour has more gluten, so it has more stretch for lighter bread, and we all like light French bread. If you don’t have or can’t find bread flour, just add 2 Tbs. vital gluten (found on the baking isle) to the flour. That will do it.