I need an idea on how to immediately "frost" a window with the wave of a hand, etc. I need to be able to write on it, like you might do on a car window in the wintertime.

Any ideas will be appreciated.

Thanks,

Amos McCormick

Only thing I can think of is compressed air....the cold would do the "fogging".

Bryan

Perform in Antarctica.

I saw a show on the travel channel once where they have a bathroom that's see-through, but when you walk in and lock the door it immediately fogs up. It was said to be a "special" mirror with some type of crystals in it that make it fog up. I am not sure where you can get it, but you can try looking in the phone book for people who fabricate windows. Just a thought.

Josh

My in-laws stayed in a room in Hawaii that had this. You would not be able to write on it, however.

Amos McCormick

The crystals are liquid crystals as in LCD. It is the same material that is used in some laptop screens. It material becomes clear when an electrical charge is sent through it and the crystals align. With no current the material maintains a frosted glass appearance.
At this point in time this stuff is pretty pricey and as has already been pointed out you couldn't write on it.

Frosted is different from a fogged look, there is the spray can of stuff you et around the winter holidays for "frosting" the windows, it is a clear spray that, as it dries, gives the look of ice crystals. I am unsure of the contents, so if you did a bit of searching and investigating, you might be able to apply, and keep the solvent form drying too fast, then (if able to control that drying action) the crystals would form, I am not sure you could use a plain fingertip, I might use a TT with a bit of scotchbrite on the end (white color type) to write, or "scrape" into the frosted surface.
For fogging, you would need to keep the glass cold somehow, base resting on dry ice, or maybe even plain block ice, a misting of water onto the cold surface will give fog like conditions, to light ice, depending on the temperature.

You should look into special effects literature. There is one formula that uses stale beer and some special kind of salt if I´m not mistaken. I have special effects/pyro training and I have read about these things but have never done one myself. I look into my reference materials and if I find something will let you know.