Originally Posted by Prowler

I too have found that the "usual" patch glue (ex: like in Slime kits) dries out quickly. I've had some success keeping opened tubes in a zip lock plastic bag but still.... I recently wanted to patch a e-bike tube (26 x 4.5) for the grand kids to use swimming. I dug out a previously opened small tube of Rema vulcanizing fluid from who knows when. Probably found it out on a trail years ago. I was suprised that it was still liquid. And it worked just fine. I now wonder if the Rema fluid is fundamentally different from the other rubber cement type products. I'm going to bin the other stuff and stock Rema kits now.

As suggested. You can buy large cans of the Rema fluid so it must last well once opened.