Beware of “pinning” the file: i.e. tiny filings becoming wedged in the gullets.
They act as fangs, scratching the surface.
Keep the file clean, and (I recall being taught at school!) rubbing blackboard chalk into the file will reduce the risk. Don’t use natural chalk rock as that can contain tiny flint or sand grains that will damage the file as well as the work.
I have not tried it but talcum powder might be as effective… as well as giving you a rather sweet-smelling workshop!
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How to clean the file to remove “pins”? Not with a steel wire brush. Take a scrap of brass and push its edge into and along the teeth (so across the file). It will partially take on the gullet profile and push the swarf out without trying to blunt the teeth.
I sometimes use white spirit or WD-40 (mainly white spirit anyway) or thin lubricating oil when draw-filing. It seems to reduce pinning and give a finer finish, but this might be my perception – or luck.
Draw-filing is a skill worth cultivating as it can give a lovely satiny-brushed finish on mild-steel especially, and on a model sometimes looking more prototypical than polishing would.