Originally Posted by dbhdnhdbh
Winter shoe care.
I had thought that most of the experts recommended against any treatment of soles, saying that the leather is optimally treated for its use, and applications of other substance would be either useless or harmful. Now no less authority than Allen Edmonds says to
"apply a generous amount of saddle soap to the sole edges of all leather sole shoes to moisturize the sole edge and help seal it from the harsh salt and water during the winter months"
Granted, they are selling saddle soap, but what do people think of this advice?
First, the sole edge and the surface of the sole are two different things. The sole edge will expose more of the leather fiber because that is where the leather has been cut. I would suggest edge dressing for the sole edge. Edge dressing is basically a diluted liquid shellac with a high concentration of dye. This will seal the edge better than saddle soap (although edge dressing tends to wear off). For boots I would suggest a coat of Obenauf's leather oil, or if you like you could use mink oil or dubbin.
As far as conditioning leather soles in general, there are various opinions, mainly because there are pros and cons to doing so:
Sole leather is cow hide that is considerably thicker that leather used for shoe uppers, and is tanned using a different process. The tanning process for sole leather is much longer than for upper leather (oak bark tanning of sole leather can take months). The fat liquoring process is somewhat different as well, as the density and purpose of the leather is different. It is still leather however, but because it serves a different purpose it needs to be cared for a little differently.
The leather in the shoe upper is more sensitive and reactive to the moisture in your feet as it has to allow the moisture to pass through the leather (evaporate) to some degree (this is what is referred to as the leather being able to breath). There is no real barrier between your sweaty sock and the leather upper (other than perhaps a sock liner, if your shoes are fully lined). However, your shoes will always have an insole that acts as a padding and a barrier between your foot and the outsole. Most insoles are made of cork (typical in AE shoes), paperboard, or rubber (high end shoes tend to use leather insoles). The leather upper should be conditioned periodically to replace the oils lost (pushed to the surface and removed) due to perspiration (or other exposure to water).
The leather sole really doesn't deal much (if any) with perspiration, but it does deal with weather conditions. If your shoes are frequently exposed to water then it would make sense to replenish some of the lost oils (so the sole doesn't dry up and crack), and perhaps add a little water protection as well. But if you only step in the occasional puddle, there is no good reason to condition your soles (in my opinion). A leather sole does not need to be as soft and flexible as a leather upper (an effect of conditioning), and softer leather will wear and damage more easily than hard leather.