Epsom salt -- the same substance used to create a soak for sore feet -- helps you turn any window into a "frosted" window overnight, simply by brushing the glass with a super-saturated Epsom salt solution. The faux ice crystals last for up to three weeks even in warm weather, and they can be wiped away with ease.
A simple, kid-friendly frosted-window paint begins with 1/2 cup of warm water in a clear glass container such as a measuring cup. Stir in 1/3 cup of Epsom salt, mixing until the salt no longer dissolves, to create a super-saturated solution. Mix in a drop or two of liquid dish soap. Epsom salt, also known as magnesium sulfate, forms crystals when the water it is mixed until it dissolves.
Another recipe for Epsom-salt frosted windows uses beer instead of water. Mix 4 heaping tablespoons of Epsom salt into a cup of a light-colored beer in a mixing bowl. The mixture will foam up quite a bit, so allow it to sit for 30 minutes or so until it stops foaming. Keep this version away from young children who may be tempted to taste it: Epsom salt is a laxative, and beer contains alcohol, so the combination, if ingested, may not be much fun for you or the kids
Applying the Solution
To create a frosted-window effect, dip a microfiber cloth or terrycloth into either type of Epsom salt solution. Wipe down the window pane with the solution; then dab a dry paper towel over the wet window glass to absorb excess moisture. Allow the solution to dry completely, which may take at least a few hours. As the liquid evaporates, the magnesium sulfate reverts to a crystalline form that resembles ice crystals on the window.
Once you're ready to see through the windows again, wipe the windows down with your favorite window cleaner, such as equal parts vinegar and water. Use a lint-free cloth to clean the windows.