A few years ago, the coatings world was nano- crazy. Nano- everywhere. I didn’t know what it really meant since there wasn’t an agreed-on definition of “nano-.” Mostly it meant adding a little of something tiny to paint. It didn’t matter if was a 5-micron particle; if it was small, it was nano-. Now “sustainability” has replaced nano- as the hot topic. But what does sustainability really mean?