After doing a lot of detective work, I think I have isolated the ingredient that is in common of every powder that has flared up my rosacea. I cross referenced powders that have worked for me against ones that don't and here is what the bad ones had in common but was not present in the good ones:
sodium dehydroacetate
Only problem is, I can find scarce info on it. Paulas dictionary lists it as an organic salt used as a preservative. Does anyone know if this is a preservative that typically causes problems? (I know in general preservatives can cause problems) I'm o.k. with parabens but I really really want to pinpoint what ingredient in certain powders flares me up so I can carry it with me on my list of ingredients to avoid. Any input would be helpful.Thanks!