In a mixing bowl, combine yeast with 1/2 cup warm water. Let stand 5 minutes. Stir in beer, brown sugar, butter, caraway seeds, molasses, 2 tsp. salt, and 1 cup of each flour. Beat well, then gradually add remaining flours until dough is stiff and no longer sticky.
Turn dough out on a lightly floured work surface and knead until smooth and elastic. Put dough in a lightly oiled bowl, turning once to grease the top and bottom. Cover, put in a warm, draft-free place, and let rise until doubled in bulk, 1 to 1 1/2 hours.
Punch down dough, divide in half, and shape halves into balls. Put balls on a large baking sheet, cover, and let rise until almost doubled, 45 to 60 minutes. Brush loaves with egg wash and sprinkle each with 1/2 tsp. salt.
Bake at 375° for 35 to 40 minutes, or until crusts are well browned and loaves make a hollow sound when tapped. Transfer loaves to rack and let cool.
Note: Nutritional analysis is per slice.