I've use a few bottles in the past. It's just so easy to forget to close the lid. I've gotten used to closing the lid. But, the last jar, I was maybe down to 2 more attachments worth, and I left the lid open for about 1/2 hour. All it takes it about 5-10 minutes being off, and it starts getting gummy. It's still somewhat usable unless you leave the lid off for 2 or 3 hours..