Manufacturers who only need small quantities of blued screws (and other steel components) for their own watch movements use a considerable different, much simpler procedure. Screws are placed in brass shavings with the heads exposed, and apply heat with a gas flame until the desired blue color is reached. The color does not necessarily need to be the same for each batch, and the screw shaft can have a different color than the rest of the screw since it will not be noticeable once the screw is placed in a movement.

Method 1 , Method 3