The TAPPI T 831 standard specifies a test method for the water-absorption energy of corrugated core paper, namely the water drop penetration test. This method measures the time (in seconds) required for the water drop to penetrate the paper and wet the lower surface by placing a drop of water on the surface of the corrugated core paper. This method is suitable for corrugated core paper manufactured by all processes in commercial production, especially relatively unglued Cardboard, but may not be applicable for high-glued Cardboard or Cardboard with different quantities. This test can quickly evaluate the water-absorption of corrugated core paper and has important reference value for gluing performance and moisture resistance performance in carton production.