Not liking the idea of dragging hardened steel pins across the teeth, I no longer use a file card. Two other methods actually work better for me.
Scrap pieces of Formica (plastic laminate) counter top material cut into approximately 1 1/4" by 4" strips make very effective file cleaners. The thicker Formica sold in sheets and used on counter top end caps works best, but the thinner stuff is also serviceable. A few strokes across the file teeth cuts the tooth pattern into the Formica and makes it a very effective cleaner that won't damage the cutting edge.
A piece of scrap brass used as above works great for heavier cleaning needs. A cartridge case flattened on the end works well. To make it easier to use, cut the head off and drive in a short piece of dowel.