In a large bowl, dissolve the yeast in ½ cup of the warm water. Stir in the remaining 1-¾ cups water, sugar, salt, shortening or butter, and 3-½ cups of the flour. Beat until smooth. (The electric mixer is a real help here.) Stir in enough of the remaining flour to make the dough easy to handle. Turn the dough out onto a lightly floured surface and knead until light and elastic. Place in a greased bowl, cover, and let rise until doubled in bulk, about 1 hour. Punch the dough down and divide it in half. Shape into 2 loaves and place in greased loaf pans (either 9x5-inch or 8-½x4-½-inch). Brush lightly with melted butter, cover, and let rise until doubled in bulk, about 1 hour. Preheat the oven to 425°F and bake for 25 to 30 minutes, or until the loaves are golden brown and sound hollow when tapped. Remove from the pans, brush the tops with more melted butter, and cool on wire racks.