How a Solera Works (and Why Westward Says Milestone No. 4 Can't Be Repeated)
Portland's Westward Whiskey has opened pre-sale for Milestone Edition No. 4, its annual single malt release. One line in the announcement stopped us: the whiskey is "drawn from our Solera that can't be repeated." That's not marketing fluff. It's a real description of how a solera works, and the math behind it is one of the more interesting ideas in blending. Here's what's going on. What a solera is A solera is a blending system where the vessel is never emptied. Instead of filling a barrel, aging it, and bottling all of it, a producer draws off part of the aged spirit, then tops the vessel back up with younger spirit. Next time, they draw part again, and top up again. Forever. The technique comes from sherry, where it's run as tiers of barrels: wine is drawn from the oldest tier, which is refilled from the next-oldest, which is refilled from the one above it, with new wine going in at the top. Many whiskey and rum producers run simpler v...