Q: I would like to know how to clear the water in old snow domes. The water in mine has gotten very cloudy.

A: The liquid would have to be replaced. There are a few repair services that will do it, or you can attempt to do it yourself. But it’s difficult. Hold the snow dome upside down before you try to separate the top from the bottom. If it’s glued together, you may be able to soften the glue first by immersing the snow dome in hot water. Snow domes with black plastic bases or brown pottery bases made in the 1930s and 1940s were held in place by plaster of Paris, which can be carefully chipped away. Domes with new shiny black plastic bases, black pottery bases (1940s), or cobalt blue bases (1920s) cannot be opened unless they have a threaded base, and very few did. If you can open yours, pour the original liquid through a cloth so that the “snow” is separated from the liquid. Use distilled water to refill the dome. Adding about 1/2 teaspoon glycerin to the water will make the “snow” fall more slowly. Snow domes should not be stored in the dark. Exposure to light keeps the liquid clear. But don’t keep them in direct sunlight. The glass can magnify light rays and may start a fire.