Abstract: A dynamic mixer (40) comprising a rotatable structure (10, 111, 11, 1, 2, 3, 4, 5) having a cylindrical base (14) having a connector disposed at one end, an opposing thinned end, flights of 3 to 6 blades (11, 12, 151, 61), separated by a notches (13, 18) the blades (11, 12, 151, 61) have an inlet face facing the connector end, an outlet (30) face facing the thinned end, a leading edge (21) facing the direction of rotation, a trailing edge (20) opposite the leading edge (21), a standard leading face (154, 65) which tapers from the leading edge (21) to the outlet (30) face and a standard trailing face (166) which tapers from the trailing edge (20) to the inlet face, or a reverse leading face (154, 65) which tapers from the leading edge (21) to the inlet face and a reverse trailing face (155, 66) which tapers from the trailing edge (20) to the outlet (30) face, the notches (13, 18) are offset from one another and the article is adapted for use in a dynamic mixer (40) to mix viscous material when rotated in the m