Lighting Anyone seen powder coat coming off passive heat sinks?

[wwwillie]

the part said "anodized". this means the top layer of atoms will create a oxidlayer that works like a coating.

Wikipedia:
"Anodizing is an electrolytic passivation process used to increase the thickness of the natural oxide layer on the surface of metal parts."

https://en.wikipedia.org/wiki/Anodizing

so once the layer is thick enough nothing can react with the metal, but the drilling killed the layer and the chain reaction began.

Bingo!
That's what I am looking for. A good bit different than powder coating the OP was discussing.
Thanks