According to Torben Schiffer bees put holes in the propolis layer on purpose to achieve the effect of functional clothing
Torben Schiffer presents in the name of HOBOS electron microscopic images of holes in the propolis layer online among a theory of their formation and effect. It is stated that bees create these holes on purpose to ensure the removal of moisture by water vapor diffusion. Supposedly, they achieve an effect such as that of functional clothing (like Gore-Tex) by this means that allows water vapor diffusion but prevents the permeability to water in its liquid form. Several questions arise from the article.