Char Levels

Char numbers are shorthand for a cooperage’s intensity-and-time specification. You’ll commonly hear #1 through #4, with #4 nicknamed alligator char because the cracked black surface can resemble alligator skin. Exact seconds and procedures vary by cooperage, so treat any universal chart you find online as a rough guide, not a fixed standard.

Whiskey doesn’t interact with one uniform surface. Beneath the carbonized char layer sits a heavily heat-altered “red layer,” then a more lightly toasted zone, then progressively less-transformed oak further out. Whiskey moves into and out of that gradient as warehouse temperatures rise and fall across years of aging — which means much of the flavor work is happening behind the black surface, not on it.

#4 is often called “alligator char” because of its cracked carbonized surface. But char number alone still doesn’t tell you the full barrel story.