Scald milk; let cool to lukewarm (105° to 115°). Dissolve yeast in warm water; let stand 5 minutes or until bubbly.
Combine milk, dissolved yeast, 2 tablespoons sugar, and 3 cups flour in a large bowl; stir well. Cover and let rise in a warm place (85°), free from drafts, 1 hour or until doubled in bulk.
Stir mixture down. Add 4 cups flour, remaining 1/2 cup sugar, eggs, shortening, and salt; mix well. Gradually stir in enough remaining flour to make a stiff dough.
Turn dough out onto a floured surface; knead 10 minutes. Place in a greased bowl, turning to grease top; cover.
Let dough rise in a warm place (85°), free from drafts, 1 hour or until doubled in bulk. Punch dough down; cover and let rest 10 minutes.
Divide dough into 4 equal portions. Divide each portion into 3 equal pieces. Shape each piece into a 12-inch rope. Braid ropes, pinching ends to seal. Place braided loaf in a greased 9- x 5- x 3-inch loaf pan. Repeat procedure with remaining 3 portions of dough.
Cover and repeat rising procedure 1 hour or until doubled in bulk. Combine egg yolk and water; beat well, and gently brush over top of loaves. Bake at 325° for 45 minutes or until loaves sound hollow when tapped. Remove bread from pans immediately; cool on wire, racks. Brush with melted butter.