Wyeast has been making pure liquid yeast cultures since 1986. At Wyeast, their goal is to provide the freshest and best selection of beer yeast. Each pack contains 100 billion yeast cells when it leaves the lab. Their packaging contains the unique "activator pack." Place the Wyeast packet in your hand and smack it with your other hand to activate.
Our Product Warranty states that we guarantee the viability of the yeast in our Activator™ packages for 6 months from the manufacture date assuming that they have been properly shipped, stored and handled. Our superior packaging material provides 100% oxygen barrier and UV light protection making this exceptional guarantee possible. During this 6 month guaranteed shelf life, some loss of viability is to be expected. This will vary from one strain to another. Activator™ packages that are 4 months old or older may require additional time to swell after activation.
Activator™ packages will sometimes swell slightly, or moderately during shipping or later while properly stored. This is not an indication of deterioration if the package is less than 6 months old and has been properly handled. This is result of trace amounts of nutrients, still available at the time packaging, causing small amount of culture activity and CO2 production. Some strains are more prone to this than others.