Originally Posted by BradleyBrew
mr. malty puts dry yeast at 2+ years old at 50% viability.
And it says that yeast slurry is only 10% viable after 2 months. I've had no problems straight pitching slurry after 6 months (not what I would normally do).
Mr. Malty is not the bible, and is generally way wrong in yeast viability calculations.
However, to counter your comment; in 'Yeast', (written by Jamil, who also put together the Mr. Malty calculator), page 160, shelf life of dry yeast, "Stored under typical refrigeration temperatures of 38 F it only loses about 4% of its viability per year"