I purchased the 10 Red Star Sampler Pack Wine Yeast. Out of 10 packets, 1 worked, 6 did not, and 4 I have not tried. Followed the directions on the packets to rehydrate the yeast (1/4 cup water, 35-38ºC, 20 minutes or more). There was no reaction from the yeast. Zero, zip, nada.
Wrote to North Mountain Supply. After all, they do enclose a little card with each order touting their warranty "We will provide free replacements and troubleshooting if for any reason the yeast does not activate before the expiration date." The reply I received was a bit condescending and told me to pour the yeast (the unreacting yeast mind you) directly into the wine and allow 24-48 hours to see a reaction.
I think not. For starters, those are different instructions than the ones from the manufacturer. Second, if the manufacturer's directions are not leading to a reaction from the yeast, why would I put that same yeast into my wine mix and potentially ruin it?! Finally, there is the matter of not honoring their warranty which is the reason I bought this sampler pack in the first place. Why even offer it?!
This is one product and vendor I will not use again. The product does not give consistent results (other reviews reflect the same) and the vendor does not care to correct the issue.