a review for copper heatsink, Edit: Removed Site Link
Regarding that link that was totally unnecessary
CRCs QD Electronic Component Cleaner available at any auto parts store will clean even aluminum to a nice shiny new look in literally seconds with no reactions and perfectly safe for plastics.
A much safer cleaning solution compared to boiling on the stove in vinegar and salts!
IMO boiling a heat sink like that is stupid, you're subjecting the heat pipes to temperatures it was never designed to endure.
There's no place for the expanding liquid in the heat pipes to go because all of the pipe is hot, so pressure will equally build inside the pipes.
The heat pipes themselves could expand, or warp, or leak, or worst case burst in the boiling liquid, hurting anyone standing in the vicinity!
Your sauce idea won't hurt anyone, the boiling link could cause someone to actually get hurt so I suggest a Moderator get involved in this thread, for the safety of other users at THGF.