Combine water, starter, the 4 cups flour, sugar and salt in a crock or glass
bowl. Mix well, cover lightly with a towel or cheesecloth folded into several thicknesses,
and let stand at room temperature for approximately 18 to 24 hours or until the
dough has doubled in size.
Mix 1 cup of the remaining flour with 1/2 teaspoon of the baking soda and stir
this into the risen dough until it is very stiff. Turn the dough out onto a floured
board and knead approximately 1 more cup of flour and a little more baking soda
into it. Knead it for 5 to 10 minutes or until the dough is smooth. Shape into 2
long loaves or 1 large round loaf, place on a lightly greased baking sheet, cover,
and let stand in a warm place for 3 to 4 hours or until almost doubled in size.
Heat oven to 400 degrees F. Brush a little water on top of the loaves and make
a few diagonal slits across the top with a sharp knife. For a crustier bread, place
a shallow pan of water in the bottom of the oven.
Bake for approximately 45 to 50 minutes or until the crust is a medium dark brown.