Originally Posted by airving
I thought that was the purpose of adding k-meta and sorbate: to stop any live yeast from starting further fermentation. Note that I'm not suggesting trying to stop an active fermentation: everything I've read says to add those prior to back-sweetening and you should be safe. Is that not your experience?
It is safe as long as your ferment is complete. It is a fine line. If you have live yeast in the wine, and fermentable sugar...they will use the sugar and then die off in the presence of k-meta plus sorbate. K-meta and sorbate does not kill the yeast, just stop them from reproducing. Hence the recommendation of fermenting dry, racking, then allowing to clear, degas, stabilize with k-meta and sorbate, backsweetening and monitoring with hydrometer checks to confirm it is stabilized. Or if you chaptalize you can aim for a planned for residual sugar plus yeast die off due to alcohol toxicity..it works once you get the hang of it.
I actually had an entire case of commercial wine bottle ferment six months after I bought it. Turns out it was not dry when stabilized and backsweetened. The cool storage temp kept things at bay, but when I grabbed one bottle and it warmed up in transport...well let me just say my car trunk needed major cleaning. Lost the rest of it for same reasons. It was sparkling when opened cold but nasty stuff. Refund given.