Being an errant coward with respect to sulfuric acid from a battery I have relied
on the great idea that is known on various sites:
White Vinegar.
I tested it with around a dozen old drills I found in my house and stored out of nostalgia when I
moved in 41 years ago. They belonged to the original owner who built
the house in 1918 and was a renowned wood carver in the US.
I got a plastic pail and submerged them in the vinegar. The next morning all the rust
had been displaced. I then washed with baking soda and water after which I oiled them.
Having never been successful in sharpening drill bits on my bench grinder I took a chance
of ordering Drill-Doctor. Miraculously from my first try, and reluctantly doing what any red blooded
male never does freely, I followed their instruction DVD and each antiquated drill was sharpened.
I then took a coated metal drill that I had dulled on SS and again success.
Returning to the acid, since I used to develop films and prints I have a gallon of Glacial Acetic
acid for stop baths. I mix 10cc Glacial TO a liter of water [NOTE: never add the water to the acid if you
value your eyes! Acid slowly poured to the liter of water.] to get the rust removing results.