Good morning:  We make leashes and collars with biothane.  We recently noticed that the collars our dogs are wearing often become more stiff and a little shiny after a few months of wearing the collars.  Do you happen to know why this is happening or if there is something that can be done to prevent this?  We advertise the soft and flexible and like leather but after some wear, that claim is not true.  We look forward to hearing from you.  Best regards, Shana Klein