I'm not a hoarder by any means. When an item runs out of foreseeable use, I put it in this special place I call "the trash." Or in a designer (cardboard) box destined for exotic places like Goodwill. I've moved over 20 times in my life. And every time I move I become less and less attached to the things I have to wrap, package, carry, load, unload, unpack, and wash.
I cannot say the same for icing. I am drawn to it. I love it and the endless possibility it holds. I love it for the color that it is and the color it could become. I adore the way it moves in a bowl and erases its own lines and wrinkles. (Seriously, who *wouldn't* love that??!!) I love the smell of it and the shiny gloss on the surface. I can't let it go. There was a point where I worried that it was ruining my marriage because I was getting rid of food instead of icing to make room in the fridge. Luckily, I discovered even smaller bowls to store it in.
The problem.... besides throwing out perfectly good food to make room for it.... is that icing gets crusty and weird and not at all what you want to be using on gorgeous cookies after a few days. It took me a long time to accept this fact. And even longer to realize there was a solution.
I have used this trick many times when I tried (unsuccessfully usually) piping with those PME #0 tips. (In my defense, I think I got a broken one. That happens, right?) And one day I realized I could also use this trick with icing that had passed its prime (but is still very much valued by society.) Simply buy and wash some new nylons. Then cut them up into 2 inch squares. Place your coupler in your piping bag and put the nylon over the top of the bag/coupler before screwing the tip and ring securely on to the coupler. The nylon will catch and the dried up icky bits and leave your tip free to pipe beautiful lines and designs as it pleases. Like any good filter, sometimes you'll have to switch out the nylon before you're done.