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.
Used at much higher concentration (for instance on a washcloth), such preparations (especially in liquid format) may also be used to wash skin or hair, so they are sometimes marketed for combined purposes; in a few cases, mild household detergents for hand washing of articles have also been labeled for such purposes, or for preventing soap scum on the bathtub (with or without foaming).
The dubious claim had been made that their normal use (diluted in a tubful of water) would substitute for soap and/or rubbing to clean skin.
Main function of cationic surfactants is conditioning and are hence used more in personal care products such as shampoos and conditioners.
Liquids must be formulated to retain uniformity as solution or otherwise on storage at expected temperatures, and preserved against microbial growth and oxidative breakdown.
Formulation is also directed at minimizing adverse effects on the skin and exposed mucous membranes of bathers.
Trends merged when the hot tub, which originally had still water, with its increasing popularity became more commonly a communal whirlpool bath.
It is possible to produce baths with bubbles simultaneously in and on top of the water (as in a poured beer), but the combination has not been popular.
Mechanically aerated baths for tissue debridement of burn victims typically have added anti-foaming agents to counteract the film-forming properties that some medicinal additives have as a side effect, but the anti-foam is sometimes omitted or reduced for children to give them more of a pleasant distraction during debridement.