Place shortening in small plastic food bag. Flatten shortening between plastic sheets so it is thin and return to freezer. This allows shortening to become hard enough to break, into tiny pieces when added to dry ingredients. Tear 2 pieces wax paper about 15 inches long and place on counter, Sift flour, baking powder, baking soda, sugar and salt onto wax paper. Place empty sifter on top of bare sheet of wax paper, lift sheet of wax paper holding sifted dry ingredients by sides and pour through sifter, sifting onto bare wax paper. Sift back and forth 3 times, then sift once more into large mixing bowl. Remove shortening from freezer. Cut into small bits, about 1/4-inch square. Drop shortening bits into bowl of dry ingredients and, using fingertips, lightly rub shortening and flour together, occasionally tossing flour mixture so you touch all particles of shortening with flour. When mixture has bits of flour-covered shortening throughout, begin adding buttermilk. Using fork, add buttermilk, lightly stirring to mix with dry ingredients. Cover board or surface with dusting of flour. Gather sticky mass of dough and place on floured surface. Dust hands with flour and gently knead dough, adding enough flour only to make dough manageable. Pat dough with hands or roll with floured rolling pin into round 1/2-inch thick. Using 2-inch cutter, cut out biscuits and place touching each other in 3 rows, in center of greased baking sheet. Place on middle rack of 425-degree oven and bake 12 minutes, or until lightly golden. Remove from oven and serve hot or warm. Makes 19 (2-inch round) biscuits.