Place cage over another Tupperware container. Place one sponge on the black side. Cut two 3 mm Whatman Papers slightly smaller than the sponge. Wet one piece of the Whatman Paper pieces with transfer buffer, then place on sponge. Lift gel, place on Whatman Papers.
Place nitrocellulose on gel.
Pour excess buffer on gel, use gloved hand to chase bubbles. Wet the remaining Whatman paper, lay on nitrocellulose. Place other sponge on top. Close the transfer cage. Take to transfer box in cold room.