About Bubble Lights

Once one of the most popular styles of Christmas Light available, and still part of many decorations and traditions even until today, bubble lights are an instantly recognizable part of the Christmas season.

Bubble lights work by a simple reaction. They consist of a clear light bulb, originally a C7 sized bulb but often mini in size these days as well, contained in a base with a cap. There is a reservoir of liquid in the cap as well, that extends out of the base in a long tube, similar to a mini style bulb in shape but longer.

The liquid within is most commonly methylene chloride, a lightweight colorless liquid with a boiling point only around 100 degrees F. This low boiling point means that when heated by a bulb in the base of the device, boiling occurs. The pockets of gas then immediately travel up the tube of the bubbler, catching light from the bulb as they do. The top of the tube is much cooler, allowing the liquid to reform and cool, so that the reaction continues. For this reason, even with the changes in technology a majority of true bubble lights are incandescent. As LED bulbs are cool to the touch they often don’t create the heat needed for the reaction.

Bubble lights are recorded as having existed as early as the 1920s, and were at the height of their popularity in the 50s through 70s. They appear in other forms besides Christmas bulbs, being a very common design for children’s nightlights as well. They were supplanted in popularity by T lights, partly due to the creation of the second but also due to the original creator of bubble lights shuttering in the 60s, but they still persist until this day.