And the oils stuffed into the hide at the tanning stage make them remarkably water resistant.
Aero FQHH jackets are great at repelling rain and they are warm enough for fall temperatures, say anywhere above 5 or 6 degrees celsius, but below that, for me anyway, they tend to get stiff and cold -- probably because of all the wax and oils in them. As far as keeping me dry and repelling rain though, they are great and much better than the naked cowhide Schott (with its zip-in liner of course), which is better at keeping me warm in colder temperatures, but useless in heavy rain because it soaks up water like a sponge (naked cowhide says it all). Having said that, I still wear my Aero FQHH jackets (including my beloved Highwayman and my lovely Bootlegger) out in freezing cold weather because they are so cool and I usually suffer the consequences of Berlin's dire winters as a result. I might have to start throwing a pea coat over them in the soon-to-be blizzard weather. And I am talking about zero weather here -- bottom 30s to 20s Fahrenheit!
Cold as a witch's you know what!