Vapor Chef. Now, I listed one, but I have to say this.
The question needs to be: what vendors are free of diacetyl, acetoin (
acetyl methyl carbinol) acetyl propionyl
(2,3 pentanedione/PD) or
any of the diacetyl substitutes(?). Many of the "substitutes" are themselves so close to diacetyl that now the concern for occupational hazards is pertaining to the inhalation of diacetyl
and diacetyl substitutes.
IMO, it's dishonest, ignorant, or a willfully misleading sales tactic to proclaim that "We sell diacetyl free liquids" when in reality, if they sell buttery/custard type vapes, they sell liquids that contain diacetyl substitutes that are essentially diacetyl in disguise.
That's the big thing to know, like stated on PA's website: "[p]retty much by definition, a vanilla custard flavor,
no matter who makes it, will have both acetoin and acetyl propionyl (or diacetyl) in it."
Now, I am not saying that inhaling diacetyl or its substitutes is bad in moderation (though I prefer not to vape those flavorings), but I
am saying that if you think "diacetyl free" is
not just marketing, look up these terms: acetoin (
acetyl methyl carbinol), acetyl propionyl
(2,3 pentanedione/PD) or diacetyl substitutes.
If a vendor says "diacetyl free," just ask them if they use any diacetyl substitutes to be clear. Just like Vapor Chef says on its website: Our flavor extracts come from reliable safe sources, are diacetyl, acetyl propionyl and acetoin free, and are specifically formulated for vaping.
Once again, I am not saying diacetyl is bad (though I want none), but know that if you MUST have custard or buttery vapes (buttery pancakes, waffles, popcorn, etc.,), you're likely messing with the diacetyl family of flavors! Just ask to be sure if you care one way or the other. And by no means are the diacetyl substitutes only used in vapes labeled "buttery" or "custard," you have to ask to be sure.
Resource: CDC - Flavorings-Related Lung Disease: Exposures to Flavoring Chemicals - NIOSH Workplace Safety and Health Topic