I saw some comments about the charcoal film that appears on some tools. That's carbon and it only appears on tools with high carbon composition, not tools high in alloy steel. Ironically, that film would actually make a great rust inhibitor, akin to black oxide, if it wasn't so messy to the touch. It wipes off easily with any light abrasive pad (Scotchbrite, 0000 steel wool) and a penetrating oil of your choice.
At the risk of sounding like a broken record or a salesman, I never use anything other than Evaporust or Metal Rescue, a competitor to Evaporust in the mysterious and miraculous water-based, non-toxic, acid-free, Ph-neutral de-rusting solutions category.
What's not to like? No mask required. No gloves required. Just hang the rags up to dry. And when it's finally lost its potency, many weeks and dozens and dozens of tools later, you can toss the dark brown liquid out as carefree as tossing a bucket of detergent after washing your car. It is quite literally classified as a detergent and safer than dish soap.
Because I'm a skinflint, I was filtering it last year, to try to eke every ounce of magic out of ever molecule, but I stopped that this year when I concluded the results were negligible, a decision made that much easier when my Tractor Supply dropped the price from $21/gal. to $17/gal.
As a PSA, there are several old threads on this topic linked in the Index if anyone really wants to read more debates, testimonials, tests, and critiques.
I think people would be surprised to discover how commonly these solutions are used even by those who like their hobby to be accompanied by officers, rules, newsletters, monthly meetings, annual swap meet soirees, a fancy name beginning with "Early" and ending with "Association," and, oh yeah, dues.