I have a spray bottle filled with a diluted Star-San solution that I used infrequently. Now I'm back to using it on a regular basis and it has a strong scent that is reminiscent of Windex.
Is it still safe to use? Could it just be reacting with the plastic of the bottle? The bottle is a standard all-purpose HPDE sprayer which should be fine.
Edit: It's about a year old and the pH is reading quite high at 7-8.
Star-san does not smell like Windex.
I would not use it in a food and/or beverage environment. Even if it is "safe" to use, it could still impart a nasty flavour or aroma. You've probably put a lot of effort into making your beverage, why risk ruining it for the sake of 20 cents worth of sanitiser in a cheap plastic bottle.
Dilute Star-San should be crystal clear, and have a pH under 3.5. Five Star Chemicals (makers of Star-San) recommend diluting a new batch every time. The shelf life of the concentrate is 2 years, and there should be a date on the bottle.
That said, many home brewers use diluted Star San after the "immediate use", me included. But I make a new batch after a week or so.
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