Originally Posted by DWFII
I agree with you...it begs the question, though, doesn't it?-- Compared to what?
The topic is whether leather soles with Tobys causes a faster destruction of the insole compared to pure leather soles, isn't it? Quick research reveals that one's feet are among the most perspiring parts of the body, with more than 250,000 sweat glands each. In one day, each foot can produce more than a pint of sweat, about half a liter for us Europeans. Given usual usage, a fraction thereof remains in your socks, in the shoe, and also in the air that may be pumped in and out of the shoes while you walk. So, we can probably agree that the amount of sweat in your shoes is affected at least by
- the sort of socks one wears,
- how often one changes socks during a day,
- how much one walks,
- the type of shoes, and
- its fit.
For instance, "closed" shoes like boots are less likely to have air pumped in and out during walking, so their insoles have to deal with more moisture compared to 'common' shoe types. My guess would be that the socks absorb the larger amount of moisture. Expressed differently, a bad habit of wearing the same pair of socks for two days in a row is likely to have a worse effect on the insoles than Topys. We can probably also agree that the rest of the sweat is absorbed by the upper and the insole alike. Without further information, absorption is a matter of the available surface. Consequently, the upper absorbs a larger fraction of the sweat compared to the insole. It's hard to say -- given all the variables -- how much moisture remains in the insole after a day of wear. For the sake of the discussion, however, let's assume it's a teaspoon full of water, basically. Now, let's consider evaporation... We can probably also agree that evaporation is also a matter of available surface. The upper has larger surface, so it should dry faster than the insole. Your analogy to a teaspoon, however, fails here since is has a smaller surface compared to the insole. For a fairer test, you should put a teaspoon of water on a small plate and have it rest for 24 hours. We can probably also agree that the layer of cork, tarboard or tar paper is a barrier to evaporation, so only another fraction of the moisture in the insole will ever reach the outsole. In other words, some amount of moisture will probably remain in a Goodyear-welted shoe forever unless it's used seldom. Now, how much moisture could ever reach the outsole? A millimeter or two, maybe? Let's say five. So, this is what a Toby would do: Prevent five millimeter of sweat to evaporate from the inside. At the same time, though, it prevents outside water to be absorbed by the outsole. It's really hard to tell what the net effect would be. Even if the net effect is negative, there's also the question if the cumulative effect matters. Consider for example the different prices of shoes. A rather cheap 400 dollar shoe is unlikely to be affected by the cumulative effect, because it's probably broken due to other causes before moisture will matter. 1000 dollar shoes are more likely to live long enough for Topys to have a negative effect; even more so for 2000 dollar shoes. In other words: Just the average price of shoes may explain the difference between your and NickV's observations, provided Nick repairs less expensive shoes on average. tl;dr
Science is complicated.