I just finished building a Copper Low D with a wood fipple. I had to tweak it a lot (went through 5 to 6 fipples, widened the window, etc). Anyway, I was able to eliminate the airy sound and got a nice clear tone by really extending the length of the fipple, making the window really short and wide. (I love the sound! 
). However, I now have a problem that I haven’t had with other whistles I’ve built. I have a clogging issue. The smallest amount of moisture in the airway channel kills the sound.
What are the tricks in dealing with this? Am I missing something obvious?
Thanks,
Tom