I have been using RI for years and once in a while I have awful problems with my tiny (0 or 00) getting clogged. Like, change the tip and the new one is clogged again 30 seconds later. I sift my powdered sugar every time, and i keep the mixer bowl covered with a damp towel nearly touching the icing so no crusties form on the sides that could fall in while I;m prepping all my colors. Any ideas?

Straining your icing through a new, clean, stocking helps.

thanks! i will try that next time

I was going to suggest the same thing - the stocking trick.