In a large bowl, dissolve 2 1/4 teaspoons yeast in 1/2 Cup warm water. Blend in starter batter, 2 teaspoons sugar and the salt. Add 3 1/2 cups flour and beat with a rotary beater 3-4 minutes. Cover and let rise until double in bulk.
Mix soda with remaining flour; gradually mix into risen dough, adding enough to make the dough stiff enough to make into loaves; turn out onto a floured board and knead 8-10 minutes.
Shape into 1 large or 2 smaller loaves and place on a lightly greased baking sheet. With a sharp knife, make diagonal cuts across top of dough. Let rise until double.
While loaves are rising, preheat oven to 400° F. When loaves are ready, bake for 35-40 minutes for medium loaves or 40-45 minutes for large loaf. Remove from oven and brush tops with melted butter. Let cool before serving