In the string 'cleaning a file' ; the use of 'chalk' was mentioned. I
do not know what the ingredient is in "blackboard chalk"; but it may
not be actually true chalk or a "flashed chalk block" of Magnesium
Carbonate (MgCO3). Magnesium Carbonate contains carbonate ion (CO3).
This (I think) is what you want to use on your files - to 'prevent
clogging'. At least, it is what I use. It is the stuff used by free
rock climbers, weight lifters, athletes (not to be confused with
their use of resin which is sticky stuff). For athletes, it removes
or inhibits moisture on their skin; and apparently does the same for
our investment with your files.
There are many (sporting goods) suppliers of this stuff. I have a
preference for 100% pure Italian Magnesium Carbonate (MgCO3). There
are many supply sources are on the Internet and in the brick and
This probably goes without saying; when using a file, stroke away
from you, lift the file, then bring the file back for another
stroke. If you drag the file back over the metal, it only serves to
dull the teeth and clog them with debris. I protect files while in
storage with an application of kerosene as a rust preventive when out
of use. Before use (and before storage) clean files with a brass wire
or stiff plastic brush. Treated with respect, files will last for
decades. Lastly, horticultural 'chalk' is a form of 'calcium'
carbonate (different from MgCO3), having the same chemical
composition as ground calcium carbonate, limestone, marble, and
precipitated calcium carbonate. Calcium carbonate is the name of a
chemical substance, CaCO3.
Ground oyster shells are a natural product mainly containing CaCO3.
Limestone (very similar to oyster shells) is a sediment mineral
composed mainly of calcium carbonate. Horticultural lime, also called
hydrated lime or Ca(OH)2 is produced by adding water to CaO and is the
kind of 'chalk' used as a soil amendment.
Quick lime is CaO, a very aggressive substance. It is produced from
CaCO3 containing limestone or shellsand by heating it to 1200B0C,
thereby CO2 is driven off the CaCO3 molecule, leaving CaO.