Corrugated Reference Guide
Basic Weight: The weight of a paper in pounds per 1000 square feet.
Bundle: A shipping unit of two or more articles wrapped and fastened together by suitable means.
Bursting Strength: The Strength of material in pounds per square inch, as measured by the cady or mullen tester.
Certificate, Box Makers: A statement printed on a corrugated fiberboard box or a solid fiberboard box testifying that all applicable construction requirements have been observed.
Corrugated Fiberboard (single wall): Also known as Double Face. The Structure formed by one corrugated inner member glued between two flat facings.
Corrugated Fiberboard (Double wall): The structure formed by three flat facings and two intermediate corrugated members.
Corrugated Material or Corrugating Medium: Paper board used in forming the fluted portion of the corrugated board.
Die Cut: A cut made with special steel rule dies. The act of making a part of container which is cut and scored to shape by tools. Also used to denote a board which has been die-cut.
ECT: Edge Crush Test (resistance measure).
Facings: (Sometimes erroneously called liners) A form of linerboard used as the flat members of corrugated fiberboard.
Fiberboard: As used in our industry, a general term applied to fabricated paperboard utilized in container manufacture.
Flaps: The closing members of a fiberboard box.
Flute or Corrugation: One of the wave shapes in the inner portion of combined corrugated fiberboard.
Flute Sizes: A, B, C, E, K
Flute (or corrugation) Direction: The normal Direction is parallel to the box.
Joint: The joint of the box is the part where the ends of the scored and slotted blank are joined together by taping, stitching, or gluing.
Knocked Down (KD): A term denoting that an article is partially or entirely taken apart, not setup.
Kraft: A word meaning strength applied to pulp, paper, or paperboard produced from wood fibers by the sulfate process. Has less than 20% recycled paper.
Liner: A creased fiberboard sheet inserted in a container and covering all side walls.
Linerboard: Paperboard used for the flat facings in corrugated fiberboard; also as the outer plies of solid fiberboard.
OCC: Old corrugated containers- to be recycled.
Pad: A Corrugated or solid fiberboard sheet or other authorized material used for extra protection or for separating tiers or layers of articles when packed for shipment.
Panel: A “face” or “side” of a box.
Partition: A set of corrugated or solid fiberboard pieces slotted so they interlock when assembled to form a number of cells into which articles may be placed for shipment.
Ply: Any of several layers of linerboard or medium.
Score: An impression or crease in corrugated or solid fiberboard to locate and facilitate folding.
Slit: A cut made in a fiberboard sheet without removal of material.
Slit-Score: A cut made in a fiberboard sheet extending through only apportion of the thickness.
Slot: A cut made in a fiberboard sheet, usually to form flaps and thus permit folding.
Test: When not otherwise modified, refers to the bursting strength of linerboard and combined board except for those grades for which puncture test is substituted for bursting strength.
Test, Bursting Strength (Mullen): Measurement of the resistance of a material to bursting expressed in pounds per square inch. The test is made on a Mullen tester.
Rule 41, specified in the chart below, is a U.S. Government Rule for interstate shipping of bursting strength (Mullen) corrugated boxes.
Trapping: Overprinting. It is the ability to print a wet ink film over previously printed ink.
Viscosity: The resistance of liquid such as ink to sheer force or flow.
Warp: Non-flat board that exceeds 1/4 inch per 21 inch segment.
WRA: Water Resistant Adhesive mixed with starch to reduce moisture.
NOTE: Caliper (thickness of paper) and flute profile of medium are critical for stacking strength (ECT) sheets and boxes.
When choosing the best substrate (sheet) for a box, look for:
- Smoothness of liner on the outside of the box
- Ink holdout
- Gloss (reflects light) or brightness of board
- Strength of tear resistance of ECT or Mullen