Found that book still in the library and its called Knife Making by Bo Bergman.
Even if you have no interest in Knife making I think you will appreciate knives more if you read this book.
After re-reading this book I am struck again by how interesting his words are.
For the many types of wood he uses for handles including Birch Bark he uses half linseed oil and half gum turpentine.
He says the oil seeps down into the wood and forms a protective wall against damage. The oil oxidizes in air to form something called Linoxyn.
There are several pages on finishing wood including using Tar.
Hope you can find this book in your own local library.
Regards.
