Yup- Zep Alum is primarily Hydroflouric and YES, it is ridiculously dangerous. However, it does work like a bastard. They pulled it a number of years back.
Here's a hint- find an operation that commercially cleans tractor trailers. They will have 55 gallon drums of the stuff.
People as a rule tend to be generic about their acids, but don't realize that acids attack (or don't affect) metals differently. In fact, you can buy a suite of acid reagents to positively identify most metals. I recall having my V50 engine on the bench and had a hell of a time finding which acid really worked to brighten the case (I was unsuccessful).
