Bulk bin bag cassette

A new bag cassette having a main bottom panel formed by a diagonal panel (18) defined by a pair of spaced parallel fold lines and a pair of side panels (20,22) is used to protect and position a bag and for squaring a carton. The bag spout (72) is held in a reinforcing panel (66) connected to the main bottom panel (12) by a spacing panel (56) and the bag is protected by the envelope formed by folding the two side panels perpendicular to the diagonal panel. To square a box having a cross section substantially corresponding with the periphery of the main panel, the cassette is inserted into the box with a diagonal panel extending diagonally between the pair of opposed corners of the box and with the side panels in folded enveloping position substantially perpendicular to the diagonal panel. As the cassette is moved down into the box it tends to force the box into squared position. Folding out of the side panels into a position parallel to the diagonal panel completes the squaring and positions the cassette in the bottom of the box.