It's done in the tannery by Horween (or whatever tannery is making it), and it occurs during the tanning and finishing processes. It's different than just applying wax or dubbin to a roughout leather. It's apparently quite similar to how CXL is made...but that's about all they'll tell us, as they have to protect industry secrets. Here's a blog post by Horween about the leather.
12/20/14 at 8:44pm