How to Make Fog

Making Fog in a Jar

Heat water until it's very hot, but not boiling. If your tap water is very hot, you might be able to use the water straight from the tap. You can also heat water on your stove, or fill a glass container or jar and heat it in the microwave. The water should be hot to the touch but not quite boiling. Aim for a temperature somewhere between 120 and 180 degrees Fahrenheit (49 and 82 degrees Celsius). You can check the temperature with a kitchen thermometer. If you don't have a thermometer, hold your finger over the water to see how warm it feels. Don't touch the water, since it can burn you.

Fill a glass jar with the hot water. Start by pouring in a small amount of hot water, and swirling it around the base of the jar. Next, fill the jar completely and let it sit inside for a full minute. Leave the lid off the jar. The reason to start with only a small amount of water is to prevent the glass from cracking with hot water. Make sure that you're using a canning-quality jar, such as a Mason or Ball jar. These jars are intended to be used with very hot water. Set a timer for 1 minute (or 60 seconds) while you wait. This can be a good time to retrieve a metal strainer, if you don't already have it handy.

Pour out most of the water. Leave about 1 inch (2.5 cm) inside the jar. The goal is to have a very hot jar with hot water in the bottom. If you pour out too much water, you can use hot tap water to replace the water at the base of the jar because the jar itself is already hot. If you heated the water to the boiling point, you can allow it to cool a little. However, you may want to use a hot pad to protect your hand when you pour out the water. The hot jar could burn your hand.

Place a metal strainer over the jar. Rest the strainer over the top of the jar so that the basket is held inside the jar. Do not let the strainer come into contact with the water itself. The strainer should rest inside the warm air of the jar, but not in the hot water.

Fill the strainer with ice. Place at least three to four ice cubes inside the strainer, working quickly. Alternatively, you could put a few pieces of ice into the lid of the jar and set it atop the hot jar. If your strainer is too small to fit that many ice cubes, you could use crushed ice, instead.

Watch the fog form. When cold air from the ice suddenly clashes with the warm air of the jar, rapid condensation should occur, causing fog to form inside the jar. If you have an aerosol spray, such as hairspray, a quick spray inside the jar will make the fog last longer. For colorful fog, add a few drops of food coloring to your hot water. As the jar cools, the fog will diminish.

Making Fog From Glycerin

Mix pure glycerin with distilled water. You'll want to use 3 parts glycerin to 1 part water. For example, with 1/2 cup water use 1 1/2 cups of glycerin. This is known as "fog juice." Liquid glycerin can usually be found in the pharmacy section of a convenience store or grocery store. Make sure to use pure glycerin, rather than a synthetic variety. Pure glycerin is able to absorb water from the air, which is why it's used to create fog.

Add fragrance oils, if desired. Scented fog can bring an additional element to your party or theatrical event. Use 1/2 tsp (0.1 oz) of scent per 1 quart (1 L) of fog juice. The oils you use should be specifically labeled as "fragrance oils." Do not use essential oils. For a spooky circus themed scent, mix together equal parts anise oil and cotton candy oil. Create a swampy scent by combining one part campfire oil with two parts rain oil and four parts rich potting soil oil. Go for a crypt themed scent by combining one part dill pickle oil with two parts potting soil oil and two parts amber oil. Theme your fog scent around the idea of a haunted hayride by combining 1 part tall grass oil with two parts cedar oil and two parts pumpkin oil.

Poke several holes in the side of a metal can. The purpose of the can is to hold a metal pie plate over the candle's flame. The holes will allow air inside the can so that the flame burns freely. Never use a plastic can, as it might release toxic chemicals if it's burned. A coffee can, or a large soup can, works best.

Cut the top off a plastic 2-liter (2-qt) bottle. Ask an adult for help when cutting, if necessary. You'll want the funnel part of the bottle to funnel your glycerin fog. For best results, use sharp scissors or a razor blade to cut the top 5 to 6 inches (12.7 to 15.24 cm) of a plastic soda bottle. Keep the top and discard the rest of the bottle. Be careful when using any sharp blade. Wearing protective gloves may help guard against accidental injury.

Tape the narrow end of the bottle to a pie tin. Duct tape, or any strong household tape, will hold the funnel in place. A small pie tin, such as is used for a pot pie, will be sufficient for this project. The fog juice will rest against the metal of the pie tin inside the funnel to create the fog. Check to make sure that the pie tin is centered on your can, so that it's unlikely to fall off once you've added fog juice.

Light the candle. Ideally, you'll have a multi-wick candle that will create an even area of heat across the breadth of the pie tin. If you don't have a multi-wick candle (a candle with more than 1 wick), use several small tea light candles to achieve the same effect. If you do use tea light candles, make sure that the candles are closely bound together so that the heat is concentrated in the same general area. Position the pie plate over the candle Make sure that the bottom of the pie plate is near the flame but not close enough to touch it.

Pour the fog juice into the bottle. Add anywhere from 1 tsp (5 ml) to 1 Tbsp (15 ml) of fog juice to the heated pie plate by pouring it into the opening of the bottle top. A little fog juice will go a long way. Resist the temptation to get carried away by pouring too much fog juice in at once. You can add more fog juice as needed.

Watch the fog form. The heated solution should quickly turn into fog, and the fog should burst out of the top of the bottle and flow into the room. For an interesting effect, shine colored light on the fog. If you want to create colored fog, the easiest and safest way to do this is by shining colored light directly on the fog as it flows out of the bottle top. The clear droplets from the fog will reflect the colored light.

Using Dry Ice to Make Fog

Fill a large metal or plastic container with hot water. Use 4 to 8 gallons (15.1 to 30.3 L) of hot water to maintain the fog in 15-minute bursts. Try to maintain a temperature between 120 and 180 degrees Fahrenheit (49 and 82 degrees Celsius). Additionally, boiling water is not ideal because it adds its own vapor to the dry ice fog, causing it to flow up instead of sprawling down and outward. Keep your container of water hot using a hot plate to maintain your fog for a long time.

Put 5 to 10 lbs (2250 to 4500 g) dry ice in the water. Dry ice is frozen carbon dioxide, which has a much lower freezing point than water (-109.3°F or -78.5°C.) Drop the dry ice into the hot water using tongs. Typically, 1 lb (450 ml) will produce enough fog to last for 2 to 3 minutes. Hotter water will create more fog, but the hotter the water is, the faster the ice will turn to fog and the more often you will need to add more. Always handle dry ice with insulated gloves and tongs.

Watch the fog form. The extremely cold temperature of dry ice will have an immediate reaction to the hot water, causing a thick cloud of fog to form. The rising steam of the hot water, together with the melting ice, creates the effect of fog. Control the direction of the fog with a small electric fan. Because fog will naturally be heavier than air, most of the fog will sink to the floor or ground unless you force it to rise with the fan.

Add more dry ice as needed. Every 15 minutes or so, you'll need to add more dry ice to consistently maintain the fog effect. Smaller pieces of dry ice added to the water will maintain greater fog volume over time, rather than larger pieces that will great large bursts of fog. Try using a hot plate to keep your water from cooling off, or refresh with hot water from your kitchen. Be aware that water is likely to bubble out from the reaction of the dry ice and water. If you're making fog indoors, know that the floor is likely to become slippery wherever the fog is.

Creating Fog with a Fog Machine

Go to a hardware store for supplies. You'll need a few basic supplies to build your own fog machine. These supplies should be available at most hardware stores, and are not expensive. Unless you plan to keep your fog machine for a long time, most of these items can be repurposed for other projects. The items you'll need include: A 2-foot, 6-inch round sheet metal ductwork pipe. This is also known as a stove pipe, and this will be the container that you make your fog inside. A 25-foot length of 1/4-inch copper refrigerator tubing A 50-foot length of 3/8-inch copper refrigerator tubing A 12-foot length of 3/8-inch clear plastic tubing A 2-foot length of 1-1/2 inch pipe (used as a form, then discarded) A 2-foot length of 3-inch ABS plastic pipe (used as a form, then discarded) 4 pipe clamps for the 3/8" Clear plastic tubing 1 small submersible pump (80 gal/hour) A package of plastic wire ties An ice chest or bucket

Create two soft copper coils. One coil should have a diameter of 1.5 inches (3.8 cm) and the other coil should have a diameter of 3 inches (7.6 cm). Form the coils by tightly winding soft copper refrigerator tubing around a piece of PVC pipe. You should be able to wind the copper tubing around the pipes using your hands, but if you have difficulty grasping it, you could grab the tubing using pliers. To create the inner coil, wind the 25 foot (7.6 m) copper tubing around a 2 foot (0.61 m) (61 cm) long pipe with a diameter of 1.5 inches (3.8 cm). To create the outer coil, wind the 50 feet (15.24 m) copper tubing around a 2 foot (0.61 m) (61 cm) long pipe with a diameter of 3 inches (7.6 cm). Slide the coils out of their respective tubes once created.

Place the smaller coil into the larger coil. Slide the smaller coil directly inside the larger coil and secure it in place by using small wire ties. This allows the fog to pass in and around the coils, which provides the best cooling. If tying the smaller coil in place is too difficult, you can just allow the small coil to lay against the bottom of the larger one. Because the coils will need to fit inside the stove pipe, stretch them out until they roughly match the length of the pipe.

Place both coils into a stovepipe. Slide the larger coil into your stovepipe, using wire ties to hold both coils in place. The goal is to have the two coils as close to the center as possible inside the larger pipe. Hanging the coils in this way allows the fog to pass in and around the coils and cool it even better. The machine will work without using the ties, but it won't work as well.

Connect the coils. At one end of the chiller, connect the ends of the inner and outer coils using short pieces of plastic tubing and pipe clamps. You'll need to connect the ends of the coils on the other side of the chiller to a small submersible pump using longer pieces of plastic tubing and pipe clamps. Cold water will come from the pump, and circulate through the coils.

Submerse the pump in an ice chest full of ice water. The pump should be completely submerged and there should be room for a small commercial fog machine to sit beside it. The water needs to be ice cold in order for the mechanism to work, so you may need to wait 30 minutes or so after dumping the ice in the water before you can create the cold fog. Place your fog machine into the other end of the ice chest. The spout should face outward.

Turn on your pump. After a minute or so, cold water should circle through the copper tubing. Test the temperature of the copper by touching it. You should be able to feel the cold water through the sides of the copper. Follow by turning on your fog machine. Fill the fog machine with commercial fog juice and switch it on. Fog should roll out, but instead of floating up as hot fog does, it should sink to the floor thanks to the cooling mechanism.