The present invention discloses a method of producing at least a pair of interlocking adjacent layers of a paper packaging product, the pair of interlocking adjacent layers being formed of a sheet of slit paper having a slit pattern, the slit pattern upon expansion, forming cells that include land regions that are inclined with respect to a plane of an unexpanded sheet. The method comprises slitting the sheet of slit paper with beveled blades that have a first wedge angle on one side of the blades and a second wedge angle on the other side of the blades, wherein the first wedge angle is wider than the second wedge angle to produce slits that upon expansion, produce the lands regions that have angles of inclination in a range for 50 to 85 degrees.

Structures including a curved corrugated wall fabricated from a plurality of layers formed of one or more shaped strips and methods of forming the structures are described. A shaped strip used in the fabrication includes a variable profile across the width of the strip with a first edge of a strip defining a series of cell profiles of a first geometric shape and a second, opposite edge of the strip defining a series of cell profiles of a second, different geometric shape, with each cell transitioning from the first profile to the second profile across the width of the strip. The geometry of the cell profiles at either end of each cell can be designed with respect to one another to allow for radial orientation of the strip about an axis with little or no deformation or stress on the strip edges.

An extensible slit sheet paper product is produced having an expandable slit pattern that forms open cells upon expansion of the paper product. The paper product is an extensible paper having an extensibility in the range from 1-9% in the machine direction and 1-5% in the cross direction. The expansion produces an array of hexagonal cells. The expanded extensible paper can be used to wrap an object for shipping by wrapping and cushioning the object in the expanded slit sheet material. The extensible, expandable slit sheet paper can be wrapped around itself to produce a void fill product.

A buffer forming method includes the step of providing a honeycomb core that includes a plurality of sheet materials. Each of the sheet materials is formed with two dash-slitted lines. For each of the sheet materials, the dash-slitted lines divide the sheet material into a top deform portion, a bottom deform portion, and an intermediate portion. The buffer forming method further includes the steps of inserting the honeycomb core into a buffer forming machine, conveying the honeycomb core in a stretching direction using an expansion unit of the buffer forming machine to expand the honeycomb core, and compressing the sheet materials in order to respectively fold the top deform portions and the bottom deform portions along the dash-slitted lines to shape the honeycomb core into a buffer.

In the preferred embodiments, the present invention provides substantially improved slit sheet cushioning products by advantageously combining novel paper properties with novel slit patterns for improved features and characteristics. In some illustrative and non-limiting example embodiments, cushioning products of the present invention can include, e.g., a novel slit sheet material in combination with extensible paper employed as, e.g., a cushioning pad or as cushioning within an envelope product, wherein the cushioning product can be substantially more resilient, but, yet, e.g., thinner for better utilization of space.