Bill

I think, but am not absolutely certain, that chalk is very much like
pumice, or even sandstone, that is used for highly polishing wood.
The chalk should be a very very fine abrasive, and you'd want to
use oil, as you did, of course. Its finer than 0000 steel wool, so
perhaps is even better.

As to another tip, for stuck screws, and even rust, Oil of Wintergreen
is suppossed to be the finest molecular structure oil in existence.
It has a unique scent to it ( to say the least ), but with a bit of
soaking time, it really gets into tight places.

Regards, Mike Priwer