Normal, methinks. SS normally does this after being heated IINM. With use, it turns a progressively darker shade of grey too. Plus, if you dry burn it hotter it might even get BLUE... or a whole range of other psychedelic colours lol.

However, if you go beyond a certain threshold, SS DOES start giving out hexavalent chromium (which is relatively toxic), though "a certain threshold" is normally melting point (of the SS) so it really isn't an issue for normal vaping - even dry burning.

Unless your coils are shorting and melting on a regular basis while vaping ler... which already indicates that something is totally effed up with your builds anyway.

The ones you DON'T want to dry burn is Ni and Ti. Those apparently give you toxic fumes even from *JUST* dry burning (though Ti can be pulsed IINM).

Was that on SS? Hope you didn't breathe in that smoke if it was Bro. Hexachrome is some real nasty crap.

Though TBH, I've had my fair share of SS coil-melting hotspots back when I still built SS contact coils. Did manage to avoid inhaling too much of the fumes... hopefully what did manage to get into me doesn't kill me too much.

Nowadays exclusively running spaced stuff so not too much issue with hotspots and melting SS.

You need to tell.more about your setup and your.expectations frpm the heatsink. Nobody will reply your vague question.