Just few tips about my personal experience for cleaning rusty or encrusted blades. I am using the same procedure as Alan with generally a very good success and only minor differences:
. I am also using household vinegar but try to buy the 10° (10% vol.) brand which is more concentrated/ effective but still does not react with steel or iron as the H+ concentration (the active agent) is too low (or the PH too high).
. I am using a vertical container made of 2 glued PVC pipes (one small one for housing the blade in the bottom part and a flaring adaptor at the top for housing the sorsoran) which I cover for avoiding the evaporation (hence the dilution) of the acetic acid. I am removing and scrubbing the blade twice a day and carefully scrub it with a steel brush or stainless steel scrubber (with Cif detergent) for removing the softened rust.
From experience I never had to spend more than 36 hours for cleaning a blade, even those covered with black rust since 100 years.
I also tested 10% citric acid and 10% oxalic acid solution (products available in drugstores and also weak organic acids) which have the advantange of not being volatile, but I did not find them more effective.
As Alan says, the cleaning of a blade will
expose the pitting which was not visible under the rust but the cleaning process does not
cause the pitting.
Regards
