The danger, of course, in buying a BOX OF OLD FILES is that they are dull or have been banging into each other and are not going to cut too well.
A remedy for some of that is to:
1. wash them in HOT soapy water with a good brush
2. Soak them over night in kitchen strength white vinegar
3. Wash them again in HOT water
4. Dry them with a hair dryer
5. Oil them with WD-40 and wipe off all excess
The acid will erode the surface slightly and "seem to " make all the points and edges sharper.
Or, pay $20 for a file sharpening kit and do the same thing.
Piper