i would have to disagree. there is no reason to do something like that. the differance in light between the glass and the lower part would be obstructed further by letting your plants crown the fixture not beneficial enough to the canopy to justify starving the lower canopy. imo. and safety should come first both for you and your crop. 85% isnt bad but i think it will affect your plants negativly in the long run. in nature the sun ever comes in contact with any vegatation right? i believe it is the image reaper who says "when in doubt imitate nature" this technique would be a contradiction to this tried and true method. sorry for ranting. i guess what im saying is i wouldnt do it.

-secret