Aquaseal is a moisture-cure adhesive. To prevent the unused portion from hardening in the tube, follow these simple steps: Squeeze Aquaseal right up to the opening so there's no air pocket. Then put some vaseline on the threads before screwing on the cap. Now put the tube in a zip-seal bag and store it in the freezer. When you're ready to use the tube again, warm it at room temperature or in the bag in warm water and you're good to go!