TABLE OF CONTENTS Few countersink tools use surface treatments (in this book the term "coated tools" will refer to coatings rather than surface treatments that do not measurably affect dimensions). Steam treatment provides a black or blue-black surface to steel and HSS surfaces. This prevents or minimizes rust, prolongs tool life and prevents galling (which also known as "cold welding") and improves lubrication properties. It also creates an excellent surface finish. The oxide film deposited on the tool surface prevents the formation of microwelds and improves the lubrication, since the microscopic pores hold the lubricant. Tools do not have this treatment unless specifically defined as having it in the manufacturer catalogs.
