There are several methods developed to measure internal bond strength or delamination strength of paper and board. The most common are the Scott type internal bond strength which is a dynamic impact test based on the energy stored when a pendulum is released. A second method is the Z-directional tensile strength. ZDT measures the tensile strength of a specimen which is sandwiched and compressed between two adhesive tapes. After compression, the specimen is separated to determine the maximum force at rupture.