Is there an eco-friendly way to waterproof cardboard?

Yes, there are eco-friendly methods to waterproof cardboard. One effective approach is to use natural wax, such as beeswax or soy wax, which can be melted and applied to the cardboard's surface. Another option is to use a mixture of vegetable oils and natural resins, which can provide a water-resistant barrier while maintaining the cardboard's recyclability. Additionally, applying a thin layer of natural latex or using a biodegradable waterproofing spray can also enhance water resistance without harming the environment.