by Sasha
A simple way to remove
mill scale and light rust from mild steel (without scrubbing and damaging the
surface)
Mill scale is the black
gunk that coats mild steel when you buy it (what you have is actually
hot-rolled mild steel. Cold rolled mild is far rarer and more expensive to
find, but does not have this black coating).
You will require:
A non-metal liquids
container large enough and deep enough to COMPLETELY cover the armour article
you are placing in it.
Enough cheap, supermarket
bought, plain vinegar to completely submerge the armour articles when they are
in the aforementioned container.
A bit of patience and a
source of nice warm water.
Some fluffy towels that
you do not want to use for human skin again.
Now you are ready to place the armour in the container (it helps if it is
resting on something like two drinking straws, so that the vinegar can get in
underneath. Otherwise it will take longer as you need to turn the armour to
allow vinegar to reach every bit.
I prefer to strip the coatings of metal at the stage I have cut out my patterns
but before I shape or weld them. This means I can get a lot of steel soaking at
once. If your armour is already built …then so be it.
Vinegar is BAD for
leather. You WILL need to rip off all strapping and replace after polishing.
Completely cover the
armour in vinegar. If any part of the metal protrudes above the surface, or if
there is other steel lying around too close to the container then it will
corrode and die like nobody’s business. The interface between vinegar and air
is highly damaging and will even rust stainless.
Anything below the surface is going to get quietly stripped of all surface
coatings.
About 48 hours of quietly
bubbling away to itself (you may wish to stir it once or twice over the course
of time. It gets you a cleaner result)
The steel will come out
white and a little powdery. Give it a soak under some warm water (or a wash
under flowing water, same diff) and then dry carefully. This is the stage that
the metal is particularly vulnerable to airborne corrosives.
Buff on a wheel of either
stitched denim or loose calico as soon as possible using either green or white
buffing compound. This will give you a protected bright polished finish that is
better able to resist corrosion.
Use a polymer based wax
product like “Nu-finish” or turtle wax to further protect your armour.
UNDER NO CIRCUMSTANCES
USE A DRILL OR ANGLE GRINDER MOUNTED WIRE BRUSH TO TAKE BACK RUST OR MILL
SCALE.
You will permanently damage the surface and increase the surface area available
to moisture and corrosives. The fact that the metal in the wire brush is
different to the mild steel you are working will also start electrolysis, a
process where the two metals act as a low powered battery and further increase
discolouration.
Many thanks to Sasha, who originally posted this information on the
Armour Archive
forum, and who kindly gave permission for me to use it here.