Hi CometC, I see no evidence on my Deep Sky filter of "powdering", but then again I'm not able to get the 'macro' image photo that you show, nor do I have a magnifier - how did you photograph your filter? Fox
PS: over at CloudyNights, David Knisely seems to suggest that the protective lamination of Lumicon filters may deteriorate with time, depending on batch manufacture...?
http://www.cloudynights.com/ubbthrea.../o/all/fpart/2