Why does the needle thread break?

Why does the Bobbin or looper thread break?

Why do I get colour migration?

This is the transfer of colour from materials into threads which have been sewn into the seam. The result is an unsightly seam appearance and can be caused by poor tanning of the leather, poor fastness of dye-stuff materials, solvent or adhesive reacting with dye chemicals, excessive needle heat, fibre migration is the break down […]