How can I effectively waterproof cardboard to protect it from moisture and ensure its durability?

To effectively waterproof cardboard and protect it from moisture, you can use waterproof sealants or coatings such as polyurethane spray, acrylic sealant, or waterproof paint. Apply the chosen waterproofing material evenly on the cardboard surface and allow it to dry completely. This will help to create a barrier that prevents moisture from seeping into the cardboard, ensuring its durability.