I seem to find that the longer I wait to clean out my whistle, the more build up it retains. The harder part of this is the solidified white stuff (I know, it’s only X-rated from here on out…small children be advised) tends to not come out with the regular hot water. Anybody got any ideas as to how to get rid of it, it’s on the inside of the fipple?
I use a sewing needle for any hard plaque or a wooden coffee stirer for lighter stuff. (if you need to use the sewing needle be VERY careful not to scratch the fipple surface.
Erik
And when I chat about coating aluminium whistles with Teflon (inside! what do you think ?) I’m not even taken serious…
I’d still love one Lefton Teflon Overton…
Or in short Leftoverton.
I rinse mine out with water as soon as I finish playing. I suppose that might not be a good idea if you have a wooden whistle.
For metal whistles, a pipe cleaner dampened with alcohol, followed immediately by a gentle scrubbing with a flat toothpick, will take off almost any sort of gunk. On wooden whistles, I’d recommend that you ask the manufacturer.
Cheers, 
serpent
~*~ 
Serpie-Pie