The "flock" is actually some amino acids. They are neither harmful nor helpful, just unattractive. Chill filtering is a 20th century thing, probably post-prohibition. Retailers prompted it. When whiskey got cool and cloudy, the retailers decided it had "gone bad" and tried to get their distributors to take it back. To eliminate the hassle, distillers started chill-filtering to prevent the flocking.

The filtering medium is typically activated charcoal sandwiched between two pieces of silk. I believe every distiller does it and only Booker's is spared. I know of no other unfiltered bourbon.

As for the loss of taste, this is primarily a problem when an 80 or 86 proof bourbon is chill filtered. There is less loss as the proof rises. A 100 proof whiskey can be chill filtered with negligible loss of flavor, according to the people who know about these things.

<A target="_blank" HREF=>--Chuck Cowdery</A>