A nice thing with quality of shoes is that they have insoles of leather that allows the feet to breathe in a good way. This feature can be drastically reduced if you use removable insoles with different often synthetic materials that don’t breathe, and which also can clog the pores of the insole and make the leather dry out and crack.
It’s a bit confusing since the shoes permanent insole is called the same as a removable insole, so in this article I will call the former insoles, the latter removable insoles, so you can separate the two. On shoes with leather insoles it’s not at all necessary with removable insolse to protect the shoe against all the sweat, which can be the case with other types of footwear with textile, rubber, or cardboard soles inside the shoe. However, also with quality shoes it can be good with removable insoles if the shoes are a bit too big, to get a better fit. There are many different variants to choose from, and one should avoid all forms that have some sort of plastic, rubber, foam rubber, latex or similar materials that don’t let neither the feet nor the leather breathe. There are varieties that are made of leather, but has an underside in other materials, such as a mixture of rubber and activated carbon is fairly common. Although the activated carbon has its points, the rubber ruins all that not least for the leather insole in the shoe.
When a fully dense material is against the leather it’s clogging the leather’s pores and it can’t breathe. The result of this can be that the insole dries out and cracks, which of course can be very problematic and require that the insole is changed, and that the manufacturer can do this. I have personally seen this happen on a friend’s shoes, and a Shoegazing reader experienced the same thing on a pair of new shoes which insoles cracked pretty quickly after such a type of insole was used. If you have an insole of this type, it’s important to take them out after each use so that the shoes insoles gets a chance to recover at least during the rest.
The insoles that should be chosen instead is those that are made of natural materials that breathe well, as soles completely in leather or in combination with cork, as for example the ones on the top image. There are several versions on the market, such as these from Shoeboy’s or these which Shoepassion sells. Then you retain the fine qualities as leather insoles has, which makes both feet and shoes happy. You can also let a cobbler put in a permanent leather insole similar to the leather sock lining which is already there.
Insoles made of wool felt that are popular during winter don’t have the problem that they can clog the insoles’ pores, however, they get very moist so they should always be taken out and dried freely after each use, both because it facilitates wool insoles drying and so the shoes can dry with their shoe trees as usual without wet blankets lying in them.