Be thankful it is worse than the old days.
The old version contained mercuric chloride. Mercuric chloride used to be called corrosive sublimate. Mercuric chloride used to be a common ingredient in quick blues and browns. IT is an serious neurotoxin, avoid mercuric chloride. I suspect the old formula was a variation on express browns and blues that you saw around back then. Mercuric chloride, some oxidizers like potassium chlorate and perchlorate or nitrate. Avoid all of it. It will rust your brain too.
The new stuff?, I have no idea. I suspect part nitric acid, maybe a safer metallic salt and safer oxidizer. I have noticed that the steam from the new version seems very irritating, like acid. I do not use any of these anymore.
Slow rust solutions work much better for me. I buy them ready made. For barrels and such commercial slow rust solutions get me there fast enough and they look better. Old quick browns were tricky to make come out even for me.
I heat screws with a propane torch and dunk them in used motor oil. Sometimes I used cold blue.
