Hi. Back in '12 I managed to acquire a pack of Westy 12s. I allow myself one per year. There's a bit of a yeast cake at the bottom and it occurred to me: what would happen if I made a really weak starter and poured the yeastcake into it? Could I "grow" some Westy 12 yeast? (the bottle tipped sideways on my way to my friend's place, so some of the yeast got into suspension, next year's Westy will have more of a yeast cake). I like this yeast/beer a lot and wondered if I could "capture" the yeast from a beer brewed in '12. Thoughts?
You can to that but the yeast will be pretty tired after that time in a high ABV beer. One can also buy Wyeast 3787 or WLP 530 and have that yeast. Those are the Westmalle strain, but Westvleteren gets their fresh yeast pitches from Westmalle.
Westy uses the Westmalle yeast, just buy it. The yeast in an old bottle of super high ABV beer will not be healthy to try to culture.
The Westy 12 sold in the US in 2012 (12/12/12) had been aged 9-10 months before it was made available to us Yanks. Take a look at the date on your cap, something like 10.2.15 which is best before date (euro format), this is three years after brew date. You are asking a lot of a single-cell organism that has been swimming in 12% alcohol for three years to spring back into action. You can easily buy this strain fresh . . . but . . . that doesn't mean your Westy clone will taste like the original. The same yeast is used by Westmalle, Westvleteren, and Achel but these beers taste differently. The monks at these three breweries use different fermentation geometry and temperatures to create a different product. If you're wondering, the grain bill is very simple in all cases. Here's some interesting details: http://byo.com/hops/item/636-fermenting-belgian-style-beers But don't be discouraged, the fresh stuff can make excellent beer.
