I read this interesting study a while ago and thought i would share! Don't think it has been posted on FC before but if it has, please delete. This guy tested the reclaim in his drop-downs, scraped out and stored reclaim, Another drop-down and the last was the stuff from a totally clogged with reclaim rig! Quite interesting! http://mcrlabs.com/resources-post/we-tested-reclaim-and-this-is-what-we-found/ Mostly from combustion...I am sure ours would be so much purer!