Baking soda works, but... FeCl has a two part action as far as corrosion. It is a weak acid, but there is the "Cl" part to deal with as well. Once you have neutralized the acid nature with a base you will still have stray Cl atoms present, one of the most corrosive elements around. This is why many folks in the past began to believe that baking soda wouldn't neutralize FeCl. They would simply neutralize the acid and then not fully rinse all traces of Cl. The truth is that just about any base will work, I prefer ammonia, but even more critical is the thorough rinsing. This is why I use a combination TSP and ammonia. TSP is a very powerful cleanser and helps remove all traces of the FeCl, even after it has been neutralized. I take the final etch, rinse liberally with water, spray with an ammonia solution until dripping, rinse again, then dip in a strong tsp solution before the final rinse.
After this, I can leave a damascus blade setting on the bench, next to a 400X carbon steel blade and even in the humid summer months see no rust whatsoever on the damascus, while the carbon steel blade will begin to bloom, and require re-polishing, within a day or two.
