Well, if you’ve ever taken a really good look at a file, you’ll notice ridges that seem to be going in a particular direction. That’s because they are. Files don’t work like sandpaper, where you can move in every direction. Instead, files are made somewhat like a ton of little knives at an angle to shave, or cut, off layers as you push. And “push” is the keyword here, and it’s exactly the word to describe a file’s use.
Simply put, you can’t go back and forth with it. You will end up pushing those angled blades down, making them flush with the rest of the file. This causing uneven shaving, resulting in pits, rather than even layers. It also dulls the edges to make it harder to cut the material.
Basically, you hold the file’s handle in one hand and apply pressure to the end with your other hand. While doing this, you push across the material. Once the end of the file is reached, pick it up and move it behind the material to push again.
Otherwise, using a file improperly not only shortens the lifespan of it, but eventually begins damaging your material.