About two and half years ago I bought an ink sack for a repair that I eventually didn’t make. When I intended to use it yesterday I opened the plastic bag and found it almost sticking to the polyethylene bag it had come with. As it looked rather rigid, I tried to pull it and it yielded like a piece of chewing gum. I have known these sacks not to last long, but their shortness of life came as a great surprise to me, as I was planning to keep a couple of sacks in store for resacking my vintage fountain pens. I wonder if their life is any longer in always filled fountain pen. My bike’s tubes have worked without replacements for no less than a decade and I also keep a spare tube ready for years without any problem. Are there any more durable sack# out there? My Parker 51 still fills after half a century of use.