Bubble Bath Day is celebrated on January 8th of each year. The staff at National Whatever Day were unable to discover the origin of Bubble Bath Day.
The term bubble bath can be used to describe aerated or carbonated baths, or to describe bathing with a layer of surfactant foam on the surface of the water and consequently also the surfactant product used to produce the foam.
Bubbles in the water can be produced either by aerating it mechanically (in some cases using jets that also move the water) using equipment installed permanently or temporarily in a bathtub, hot tub, or pool, or by producing gas in the water in a bathtub through the use of effervescent solids. The latter can come as small pellets known as bath fizzies or as a bolus known as a bath bomb, and they produce carbon dioxide by reaction of a bicarbonate or carbonate with an organic acid.
Bath fizzies are infeasible as liquids because of the inability to keep the mixture from reacting prematurely. This is a distinction from foam bath (see below) preparations, which may be supplied as liquids or solids.
When the term “bubble bath” is encountered on the Internet referring to a gas-infused bath or pool, it is more often by a non-native user of English who may not be aware of its use to refer to foam baths (see below). In other languages the distinction is more likely to be kept by use of different words.
Bubbles on top of the water, less ambiguously known as a foam bath (see photo), can be obtained by adding a product containing foaming surfactants to water and temporarily aerating it by agitation (often merely by the fall of water from a faucet). The practice is popular for personal bathing because the foam insulates the bath water, keeping it warm for longer, and (as a lime soap dispersant) prevents or reduces deposits on the bath tub at and below the water level (called “bathtub ring” and soap scum, respectively) produced by soap and hard water. It can hide the body of the bather, preserving modesty or, in theatre and film, giving the appearance that a performer who is actually clothed is bathing normally. Children find foam baths particularly amusing, so they are an inducement to get them into the bathtub.