Originally Posted by patrickBOOTH
DWFII, something that is always on my mind is leather upper quality. What makes a long last durable upper, is it the hide itself, the tanning process, or the care that ultimately makes for a crackless upper? You hear this term breathability all the time, but does leather actually breathe? Is anything you do to an upper mostly cosmetic in the end? Thanks very much for all of your posts.
We can have all kinds of disagreements about this subject.
Bottom line is that all things being equal, the younger the animal the denser the fiber mat that is what we call leather. So...calf is a better leather than cow or bull or what have you. It will crease more evenly is less likely to contain stretch marks, scars, warble holes and other assorted reminders of the hazards of life. The downside is that calf is likely to be thinner than an older animal. So on one hand you have a leather that is refined and supple and so forth and on the other, you have a leather that may be more impervious to hard wear and even superficial damage. Sometimes tannages are tailored to fit the hide. An older animal might get a rougher treatment or a combination of tanning agents to produce a certain effect and might also be oil-stuffed. As for breathability...it is not like air is being pumped in and out of the shoe with each flex or each step. Breathability just refers to the fact that leather will tend to wick moisture away from the foot and towards the ambient atmosphere. That attribute all by itself is one of leather's great strengths, however and AFAIK has never been duplicated in a synthetic. On edit...the type of tannage may have a lot to do with whether a leather is prone to cracking or not. But the finish may have something to do with it as well. Once upon a time shoe were made entirely of vegetable tanned leather...uppers included. After WWI (?) WWII(?), mineral tannages--chrome tans in particular--became the new thing for upper leathers. Today most upper leathers are chrome tanned. One of the reasons chrome tans have dominated is that they stretch better than vegetable tannages. But they also are easier to finish with a flexible and resilient top coat--essentially a paint job...and not necessarily to be dismissed. That said, there is much to recommend using vegetable tans for uppers especially in light of the research and advancements in vegetable extracts for tanning being made. A good deal of European making is done with "crust"--a product which we don't see here in the states. It is my understanding that the crust being used is a veg tan that is undyed...allowing the after-completion finishing and antiquing that is so popular here on SF. Some will tell you that cracking is due to the tannage. Some will tell you it is due to the finishes, some will insist it is the conditioners...or lack thereof...that are used on the shoe after it is completed. There was even an English gentleman of some note , some years/decades back, who asserted that cracking was due to floor level urinals.