Good question, Suzan. I have a rack where I store cane by size. I only buy when I need more, so cane can sometimes sit around for a long time. I go by color (how the older cane looks relative to newer cane - is it significantly darker) and by how pliable it is. If in doubt, I throw it out and replace it. If I begin to cane with an older strand and it breaks, or the ends snap off rather than bending once the cane has been soaked, out it goes. It's not worth fighting to make older stuff work. It will just last for less time in the new seat and make customers unhappy. Not a situation I want to face. I hope this helps.