One often talk about the importance of shoe trees, that shoes shouldn’t stand close to radiators, and other things about how they are stored. One thing that rarely is reflected over is which kind of shelf the shoes stand on, which may be quite significant.
I recently wrote about how a pair of leather soles molded after the shoes had been walking in heavy rainfall and then left standing in my shoe rack at home, something that could be remedied if they were put on the side to dry. Another thing that could save this is if I had another type of shoe rack. I have built mine in a wardrobe with elfa brackets and ordinary white fibre boards, which has the problem that the leather soles stand on a solid bottom. For shoes, especially damp leather soles, it’s better with a shelf that allows air to circulate also underneath them.
This is one of the reasons that most “real” shoe shelves are designed with different slats or similar, another reason is that dirt can fall down on the floor and easily be vacuum cleaned. For shelves like mine, however, you can easily make a surface that lets the air circulate. I bought a thicker rubber mat that was cut to the right size and placed on each shelf.