Here is a old post of mine on the 501st main board..I tried just about every suggestion mentioned above...this is the only thing that worked..I've got plenty of miles on it now..works great!! :
I posted this over at the Sith Lords Detachment, but I figured it may be a help for all types of costumes, so heres the post :
OK..I have a BIG lense fogging problem. Heres why..I wear glasses..and I basicaly have two lenses in my helmet, the lightly tinted amber buble lenses on the outside, and a set of dark flat lenses cut from a face shield on the inside of the bubble lenses to hide my eyes. So in total thats THREE lenses I have to keep fog free. On my last troop my lenses would fog instantly and not clear up no matter how I tried to control my breathing ( I was in the suit for 6hrs, though) ..I had two fans in my helmet that day, one in the chin vent blowing out, and one in the top of the mask blowing down onto my head. I had also used a Anti-Fog spray...didn't work at all..
I have been researching and experimenting with diferent fan positions and anti- fog stuff like crazy, and I think I may have found something that may work. In all of my searching I came across and ordered this:
basicly what the Rspro Foggy Mask is is a piece of neoprene that is formed to your face. It mounts in your helmet with velcro and directs your hot breath down away from your feild of vision. I had to cut a bit of the bottom away..it is designed for a motorcycle helmet with alot of room around the neck area. What it is doing now is isolating the hot breath down and out the mouth grill...I wore the mask for a while and tried to make the lenses fog by breathing extra hard ( to the point I got a little light headed )...nothing...no fog at all on any of the lenses..the Foggy mask seems comfortable and doesn't interfere with vision , breathing or my mic for the voice amp at all.
...The real test will be on the next troop...I changed my fan set up a bit and went for a slightly higher powered fan in the chin blowing out, and a much bigger fan in the top of the mask, now blowing out as a hot air exit fan.. heres a pic...it looks a bit caveman because I want to make sure everything works before I tidy it up:
I'll be sure to update as I put some more "miles" on this set up...I am just really excited that I seem to have found something that will work!
UPDATE:THIS IS THE BEST!!! LENSES WILL NOT FOG...YAY!