The TV advert in question, which can be viewed below, was challenged as being misleading due to implications that other soaps dried the skin.
In the advert four different soaps have test paper applied to them as the voice-over explains that it is showing the drying effect on the skin.
The female voice says: "When soap damages this paper, it indicates how drying it can be on your skin. Dove is different. With one-quarter moisturising cream, Dove doesn't dry your skin like soap can."
In response to the challenge, Unilever UK said as soap was alkaline, it altered the surface of the skin and its ability to retain moisture, and that routine cleansing with soap-based products often left the skin feeling taut and dry, which was the result of damage to the outer protective layer of the skin.
“During the ad, a thin film of zein protein was used on the surface of each soap,” says a company statement.
“This protein was commonly used as an industry standard for in vitro testing for the relative harshness of surfactants by measuring the amount of protein that was removed which reflected the overall harshness of a product's surfactant.”
This means that the harsher the surfactant in a cleansing product, the more the skin is unable to retain moisture, which leads to dryness.
Unilever were then able to provide a graph which showed that several soaps dissolve a significantly high percentage of zein protein, meaning that these soap-based products had a harsher surfactant system, which caused skin to dry.
Satisfied with Unilever’s response and the acceptance that the zein protein test was an industry standard method to indicate surfactant harshness in a soap product, the ASA ruled in the personal care firm’s favour.
Skin drying is generally accepted as one of the negative consequences of soap use and some products result in varying degrees of dryness; and with this in mind the ASA concludes that as a general claim was made about soaps and their commonly accepted drying effect, the ad was not misleading.
“We understood that the complainant's concern related to whether soap in general, rather than the Dove soap, dried the skin,” says the advertising watchdog.
“We considered that the ad focused on generic soap products and we therefore considered that consumers would understand that the ad made a general claim about soaps and their drying effect on skin.”