Combine the flour, rye flour, caraway seed, baking powder, cumin, coriander, and salt in a food processor.
Add the butter, cover, and process until blended. Add the milk and process until the mixture just forms a dough. If necessary, you may add an additional tablespoon of milk.
Turn the dough out onto a floured board and allow to stand for 5 minutes. Roll out until the dough is about 1/8 inch thick.
Cut into desired shapes, place on an ungreased baking sheet, and brush lightly with egg white. Using the tines of a fork, prick the crackers all over.
Bake in a 350 degree oven for about 15 minutes, or until crisp.
Cool on wire racks. When completely cool, the crackers may be stored in an airtight container.
Makes about 40 crackers.