When using a file, when should pressure be applied?

Applying pressure only on the forward stroke when using a file is the correct practice. This technique allows for the efficient cutting and shaping of the material being filed. The forward stroke, where the file is pushed away from the user, engages the cutting edges of the file teeth against the material, allowing them to remove material effectively.

When filing, it is important to maintain control of the tool and the material, ensuring that the strokes are consistent. Applying pressure during the backstroke can dull the file's teeth, as they are designed to cut only when moving in one direction—typically forward. This not only prolongs the life of the file but also ensures a smoother finish on the material being worked on.

Other choices suggest varying pressure in ways that can diminish effectiveness or lead to poor filing results. For instance, applying pressure on the backward stroke could hinder efficiency and increase wear on the tool without significant benefit. Therefore, using the correct technique of applying pressure only on the forward stroke is essential for effective filing.