National report — The trend in cleansing agents over the past five decades has been to develop not only products that would be less drying to the skin than standard soap bars, but also to develop products that would actually deliver moisture.
National report - The trend in cleansing agents over the past five decades has been to develop not only products that would be less drying to the skin than standard soap bars, but also to develop products that would actually deliver moisture.
The result is the latest rung on the cleansing product ladder: premium liquid systems. From the users' standpoint, these leave skin looking and feeling more hydrated after towel drying. From the dermatologist's point of view, premium liquid systems ameliorate the effects of overhydration followed by drying during the normal cleansing process, according to Greg Nole, claims development manager, Unilever Global Technology Center, Trumbull, Conn.
From bar to liquid Soap, according to Mr. Nole, is the cause of cosmetic drying. Synthetic detergents proved to be the first big leap into milder, less drying cleansing products.
"Dove is a synthetic detergent bar, which makes it significantly milder and more moisturizing than ordinary soap."
The next step was to develop synthetic detergents into liquid systems; then, into premium liquid systems. Premium liquid systems offer active hydration, which is the ability to deposit significant quantities of emollients on the skin during cleansing, to help hold in the moisture of the shower.
"The normal processes of bathing and drying cause extreme fluctuations in skin moisture," Mr. Nole says. "You become very hydrated in a short time period, and then you become very dried out. This disrupts the normal skin processes. If we can keep more moisture in the skin during that shower experience, we can ameliorate the extreme fluctuations and reduce some of the disruptive effects of bathing, hydrating and drying."
Studies published in the literature show that active deposition of emollients from premium cleansers provides significant improvement in mildness and moisturization benefits, compared with the effects of regular liquid cleansers and traditional soap-bar cleansing, according to Mr. Nole.
Measuring moisture Mr. Nole says researchers typically measure dryness and damage from cleansers by using exaggerated washing procedures. With ordinary soap, the classic dry skin symptoms are increased visual dryness and transepidermal water loss, as well as a decreased hydration state of skin.
Synthetic detergents are milder, more moisturizing and less damaging than ordinary soap. They use different kinds of milder surfactants, Mr. Nole says. And liquid systems also allow lower surfactant concentrations and more formulation latitude compared to soap bars.
"But even now, you use these products and see improvement in the visual appearance of dry skin but not necessarily in actual hydration state of skin," he says.
Premium moisturizing liquids, such as the Dove Deep Moisture Body Wash, go beyond just being mild to delivering true moisturization, according to Mr. Nole.
These premium systems could deliver two things: oily materials, such as natural and vegetable oils and petrolatum, or water-soluble materials, such as glycerin and other humectants.
"There are serious technical challenges with delivering water-soluble materials, due to their tendency to wash off," he says. "At the moment, technology is focused on getting high levels of oily lipid materials into the product."
There is a limit to how much oil a regular body wash system can hold. But the premium moisturizing liquid segment is a different kind of technology, which uses a structured lamellar liquid. This offers the ability to entrap the oil in much higher concentrations, so that manufacturers can incorporate these into the liquid using a surfactant to hold them in place, according to Mr. Nole.
Using Leg Controlled Application Technique (LCAT), researchers recently evaluated the relative comparative mildness and moisturization of ultra-mild cleansers. Forty-four men and women participated in a study in which researchers marked wash sites on participants' legs and washed the sites in a controlled manner, multiple times each day for five consecutive days.
Trained clinical judges evaluated participants' skin condition, assessing the visual appearance of dryness and erythema. Researchers also conducted an instrumental assessment of skin hydration and transepidermal water loss.