Hairsprings Touched by Rust
By CLARENCE D. HINES
I have, on a 12, 16 or 18 size watch, taken the spring, when not too rusty (and sometimes they were pretty bad,) and cleaned it. I remove the spring, slip the collet on a slender pegwood or broach slightly tight, grasp the coils in the left hand between the thumb and finger and push slightly forward, enough to expose the coils.
Rinse in benzine and dry. Then place upon a screw-bluing copper strip, put a good drop of clock oil on the spring and hold over the alcohol lamp until the oil smokes a little. Remove, rinse again in benzine, replace spring on balance, re-vibrate because it will be weaker Do not shorten spring or alter collet pinning, but make the wheel slightly lighter by removing timing washers. If there are none lighten by placing balance screws in the lathe and with a sharp graver removing material under the head. Do not shorten the heads, however.
I have springs in use many years with no further rusting or bother of any kind. But unless one is skilled in handling hairsprings he had better practice.