Sheer-type pop filters (such as metal or stocking types and not open-cell foam) become much less useful when they are either close to the source (mouth) or close to the mic.
As a simple test, you can hold your hand flat about 12" in front of your face and blow on it. Using your other hand, move the pop filter in between your lips and your hand. You'll find that as it gets close to the lips, the effectiveness diminishes significantly, when it's close to the mouth it also diminishes.
The metal screens I've tried are also very 'noisy' producing high-pitched turbulent whistles when you blow on them. 'Pops' are just short blast gusts of air and once you've noticed it, you can hear the 'rush' of the metal pop screen (the "expanded metal" types) in a blindfold test. I think Stedman were promoting these a while ago, I always hated them! -
Blow on a metal screen, blow on a nylon screen, and tell me which sounds better...
Most effectiveness from 'panty-hose' screens comes when the two mesh screens are seperated by a small distance. Too close to the mouth and the disruption of the wavefront is ineffective becasue the wavefront reforms due to how the air around it is acting. Laminar flow becomes turbulent but re-forms as laminar. With a pop shield, you want turbulent.
Anyway, digression... I've used 12V heated velcro-fastened jackets on cold mics to prevent this problem, and ot's worked very well. They sell them in Canada in different diameters, designed to fit around telescopes and prevent condensation on cold telescope lenses when the air is humid. They also sell them as IMDU's (Inlet Manifold De-Icing Units) for air-cooled VWs, which used to form rings of ice inside the inlet manifold due to the vacuum and humidity in the air condensing then icing up, just like an air conditioner will ice-up if it's set too enthusiastically!
If you have a climate where you have a lot of condensation issues, you might like to investigate these, you'll almost certainly never have the problem again.
Keith
