Here it is
Brew Basement
Perfect! Is diacetyl literally buttery? There has sometimes been a "stale" taste to some of my beers; just not sure if it has anything to do with diacetyl. I'll give the brewing science articles a read.
Stale, dusty, wet cardboard, "zesty," papery, are all descriptors of oxidation.
Diacetyl is literally buttery. It is the same chemical used for movie theater popcorn. It can come across as butterscotch as well. Sometimes you may not taste it (and everyone has different levels of sensitivity to it), but you can get it in the texture. It leaves a slickness on the tongue.
Edit- The most common cause of diacetyl is incomplete fermentation. The usual culprit is temperature, being either too cold or falling as fermentation tails off. I always raise temps slightly as things settle down. Infection can also cause diacetyl, as some bacteria are notorious producers. Watch for craft tap lines at bars that don't sell much craft, as the taps can be full of diacetyl.