What's the Difference Between a Traditional Soap and a Dermatological Bar?

Amongst other factors, the most significant distinctions between soap and dermatological syndets lie in their chemical properties and origins, their effects on the skin, and their environmental impacts. We shall explore each characteristic and elucidate the specifics for each difference.

The chronicle of traditional soap can be traced back to as early as 3000 BC. It has since then been utilised for personal cleanliness and for laundering garments. In contrast, syndets have only been developed since the early 1900s, predicated on their more advanced production methods and environmental considerations. Syndets are thus designed to meet the requirements of sensitive skin.

Soap is produced through the saponification of animal or vegetable fats with an alkali or potent base, culminating in the salts of fatty acids. The triglycerides present in fats, once decomposed, discharge fatty acids that merge with the alkali to create soap. As a consequence, soap molecules that ensnare oils and dirt, thereby facilitating their removal with water. Syndets, conversely, are chemically constructed from fats, petroleum, or petrochemicals via a series of chemical procedures, inclusive of sulfonation, where fatty acids or alcohols are treated with sulphuric acid to form a sulfonate group. This process is succeeded by ethoxylation and esterification, which further alter the molecules. The final outcome is a product whose formulation can be more precisely and consistently tailored to meet specific skin requirements.

Mild natural surfactants derived from oils and fats such as salts of fatty acids are found in conventional soaps. These oils serve as the primary surfactant in soap, with their chief role being to ensnare oils and grime from the skin within the foam, which can subsequently be rinsed off. Soap constituents encompass vegetable or animal oils, caustic soda, foaming agents, scents and colourants. Nevertheless, certain combinations of surfactants and other ingredients may not be appropriate for sensitive or compromised skin, frequently resulting in dryness and irritation.

Syndets, conversely, are produced utilising a chosen array of materials that are harmonious with preserving the skin’s structure and function unimpaired. This concoction incorporates synthetic surfactants derived from petroleum-based or plant-based raw materials such as sodium cocoyl isethionate or sodium lauryl sulfate (SLS). In the majority of instances, they tend to possess a pH-balanced formulation and may be devoid of any fragrance or harsh additives, which renders them more skin-friendly compared to traditional soap. Syndet formulation typically includes vegetable oils, glycerine, vegetable butter and plant extracts (chamomile, aloe vera, etc.)

The most marked distinction between the two categories is found in the pH levels. Conventional soaps are highly alkaline, with pH levels ranging from 8.5 to 11.0, which disrupts the skin barrier and encourages dryness or irritation. An alkaline pH impacts the skin barrier as it modifies the naturally occurring acid mantle of the skin, which is slightly acidic and serves as a defence mechanism against bacteria and potential dryness. Extended exposure to alkaline substances weakens the acid mantle, leaving the skin dry, irritated, and more prone to infection. Moreover, high pH can damage the lipids and enzymes of the skin's moisture retention response. Syndets are engineered to fall within the neutral to mildly acidic range (5.5 - 7.0), which is nearer to the skin's pH - this aids in restoring the skin's barrier function and reducing the likelihood of irritation.

A comparative analysis was conducted by PAYE & al. (2001) with the aim of determining the predictive value of patch testing in assessing the skin irritation potential of body-cleansing products in comparison to the products' regular use at home. The study was carried out double blind for 10 weeks and involved 50 healthy female volunteers; half were provided with an alkaline soap bar, the other half a syndet dermatological bar. Skin reactions were evaluated clinically through visual inspection and chemical measurements. Concurrently, participants maintained records of dryness, tightness, and irritancy. The results demonstrated no significant changes, apart from a minor increase in pH for the alkaline soap bar, which was perceived as more irritating by the users. Soap chamber tests corroborated that the soap bar had higher irritancy than the syndet bar. The results imply that patch testing does not reliably forecast irritancy under normal conditions of use, although the soap chamber results are very close to consumer perception of product irritancy.

Both soap and syndets contain amphipathic molecules (hydrophilic head and hydrophobic tails) that assist in the cleansing process. The distinction lies in the surfactant composition: soaps primarily comprise anionic surfactants such as sodium laurate or sodium oleate. Whilst effective, these surfactants may provoke skin irritation. Conversely, syndets utilise surfactants such as non-ionic, anionic, cationic, and amphoteric combinations that enhance cleansing efficacy whilst ensuring skin compatibility. Sodium alkyl isethionate is a typical syndet surfactant, with low irritation when compared to traditional soaps.

Many traditional soaps are manufactured utilising animal fat (surgras soaps may be an exception). Some alternatives employ biosurfactants sourced from plants or microorganisms; however, these are not extensively used. In terms of sustainability, even synthetic detergents present more feasible options. A majority of the latest dermatological bars utilise biosurfactants from renewable sources, which have a reduced environmental impact and enhanced biodegradability. Moreover, the synthetic detergents maintain stability to a large degree across diverse pH and temperature ranges, making them appropriate for long-term applications.

Whilst traditional soaps have been in use for centuries and continue to be favoured by many, dermatological bars or syndets offer a significantly superior alternative, especially for those with sensitive skin. Syndets are engineered to be pH-balanced, gentle, and more appropriate for preserving skin health with minimal irritation. Moreover, their procurement is sustainable, offering additional environmental advantages, which is another reason why they are the preferred choice in personal care.

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