I helped the widow of a late American gunsmith clean out his shop. One of the things I sold for her was a gallon( or half gallon) of a commercial file sharpening solution. As this was about 1983-4, I don't remember the product name.
Gunny,
I have two commercial " file cards", both have short steel bristles( one has fiber bristle brush on the other side). The "trick" is to brush along the rows of teeth, not against them. To clean "pins" that are not dislodged by the card, I use the flattened neck of a cartridge case. Rarely, I have to resort to a scribe. The "trick" for all this is to go along the rows of teeth, not against them.
Mike
