Originally Posted by Oldelkhunter
... I put KG12 on a tarnished penny and it dissolved half of it in no time at all.

Not only that, it contains cyanide, according to the MSDS sheet eek
KG12 MSDS

They don't say what the concentration is ("classified information"?) and it's obviously deemed safe for sale to the general public, but still....

Canada: Everything from Eh to Zed.