Lou pointed out to me that he is still using Maysville carpet warp from the 80's with no problems. He's right, it's a great product and I've never had trouble with it. It's fair to say the problems Ive had with broken threads on this warp could be user error or a storage problem or something like that. I would never hesitate to buy Maysville warp. It's good stuff.
Thanks, Lou for pointing this out, I would not want to be misunderstood on this.
I have had some cotton yarns that became weak with (great) age, but those were fine yarns & not made by Maysville.
I do wonder if there's a limit on how old a yarn must be before it weakens, but factors like brand, storage, and color (dyes used) would affect the answer.
If anyone has more info on this, please do share it.