The Korean Boy with Curiosity

[HEYSONG]

Hello. This is my first post on leatherworkernet. I'm a young man studying to make boots in Korea. I'm learning the theory and techniques on my own every day. I have a few questions.

-Leather Selection
I want to make engineer boots as my first project, 
and I want to make them using horsehide and cowhide respectively. I'm curious which leather I should use. (Characteristics of leather not treated by a tannery) I plan to do the top coat and dyeing myself.

- I want to create beautiful stitching using leather nearly 2mm thick. I just bought a my first own sewing machine (Pfaff 493 roller poster).While preferences vary, what needle and thread should I generally use to create an upper that remains beautiful over time?

- I generally prefer the craftsmanship of brands that are now defunct in the US, such as Sears, Montgomery Ward, old Chippewa, and Santarosa. Are there shops where I can purchase the shanks, rivets, and solid brass buckles used on these items?