There are many reasons why you might want to whiten your windows or make them opaque. You might want more privacy in a bathroom or bedroom window, or you might want to diffuse the light for a greenhouse. No matter what your reason, whitening windows is possible and requires a few simple but key steps. Purchase etching cream at a craft, hardware or paint-supply store.
Clean the glass thoroughly with soap and water. Scrub the glass with the rough side of a sponge and dry the glass thoroughly with a soft cloth. Don't use paper towels, as they will leave behind small pieces of paper.
Use painter's tape to cover any areas you don't want to whiten. Tape off the window frame.
Put on gloves and goggles to protect yourself from the etching cream, which has hydrofluoric acid in it that can irritate your eyes and skin.
Dip a foam brush into the etching cream and apply a thick layer to the glass. Work the layer so that it is even across the entire window.
Let the etching cream sit for several minutes according to the manufacturer's instructions. This could be anywhere from 15 to 30 minutes.
Wipe off the etching cream from the window with paper towels.
Wash the window with washing soda and water. This will neutralise the paste.
Remove the painter's tape from the window and wash the window with window cleaner. Let the window dry completely.
Put the paper towels with etching cream on them into a plastic bag before throwing them away.
Never leave the acid unattended as it can be toxic for children and pets.