Kind of sort of depends. Most will tell you to just to cover themselves. It also helps to retain color and prevent spoilage. I've had a test bottle of my Ralphs' sitting open, as in no cap, for 3 months now unrefrigerated and it shows no signs of going bad. Still, I put 'refrigerate' on the label just 'cause it seems the prudent thing to do. If the pH is low enough, there generally isn't a problem. -Jim C http://www.wildpepper.com BTW- I've been all week in an advanced haz mat chemistry class (intro to analytical chemistry) and have always been curious about the pH of my sauces. The prof needed samples to demonstrate measuring and I just happened to have a bottle handy.... pH of 3.0 to 3.5 Cheaper than sending it off to a lab!