Sun Jan 30, 2011 12:37 pm
It depends on a number of factors. Star San is no longer effective if the pH gets above a certain level. Your particular water chemistry, and whether you were dunking stuff cleaned in PBW in to sanitize can affect your life span of previously used Star San. If it were a fresh batch that you'd mixed up and didn't use, it is still good. I keep a 1L spray bottle on hand with Star San in it for spraying down and sanitizing whatever I need... I believe that it will generally turn cloudy when bad, or at least if it is cloudy it is no longer good.
Spiderwrangler
PFC, Arachnid Deployment Division
In the cellar:
In the fermentor: Belgian Cider
In the works: Wooden Cider