Is the adhesive strong enough for heavy packages?

For standard shipping, yes. Packaging tape uses a pressure sensitive adhesive that grips corrugated cardboard on contact and holds through the bumps and temperature swings of transit, so boxes stay sealed from the warehouse to the doorstep.

• Bonds to: corrugated cardboard, kraft boxes, and standard shipping cartons.
• Holds through: stacking pressure, sorting, and warm or cold conditions without peeling or lifting.
• For very heavy loads: reinforce with the H-tape method, sealing the center seam and both edge seams.

For unusually heavy freight, a wide tape paired with reinforced or water-activated options adds extra shear strength.