28 LIFESTYLE COSMETICS
The ‘solidification’ of liquid shampoos and conditioners
Trevor Barker, Antonia Hantschel - JRS
This article will first explore the challenges and limitations of currently available shampoo bar formulations. It will then offer a revolutionary technology which allows improved performance and consumer acceptance, not just for solid shampoos but also for conditioners and other liquid products, instantly dissolving powders, tablets and paper sheets. It offers the personal care industry the opportunity to re-develop a wide range of existing cosmetic formulations into solid forms. Shampoo bars and other solid formats
are growing in popularity worldwide. The last five years have seen an exponential increase in shampoo bar launches, from around 50 in 2016 to around 700 in 2021. This trend is likely to continue apace due to the unique drivers involved (Figure 1). Unlike many drivers in our industry, it is clear that sustainability is more than just another fashion trend. The issues are real, widespread and extremely well documented. Furthermore, these issues are not going to go away. The cosmetics industry is essentially
consumer-driven. The needs and wants of the consumer are paramount when developing and marketing new products. In recent years there has been a move away from what has become known as ‘greenwashing’ towards more ethical considerations. This is, to a large extent, due to a better informed and more environmentally aware consumer base. The sustainability theme captures a wide
range of issues from palm-related deforestation to carbon footprint. It is clear that, currently, shampoo and conditioning bars, powders and tablets offer the consumer a product that ticks a number of boxes: water reduction, reduced carbon footprint and non-plastic packaging to name just a few. They represent a shift away from traditional formulations to a more sustainable and consumer-acceptable range of products.
Current technology Current shampoo bars are typically variations on syndet bars (synthetic detergent as opposed to saponified ‘soap’). The availability of suitable ‘dry’ surfactants is limited due to the manufacturing process and the ultimate dry form of most commonly used surfactants. Many liquid surfactants are unusable in their water-free form (Figure 2). A handful of dry surfactants are currently
available to formulators. The most common is sodium cocoyl isethionate (SCI), sodium lauryl sulfate (SLS), sodium cocosulfate (SCS), sodium
PERSONAL CARE April 2022 1,422
50.0% 45.0% 40.0% 35.0% 30.0% 25.0% 20.0% 15.0% 10.0% 5.0% 0.0%
2015 2016 2017 2018 2019 Figure 1: Launches of shampoo bars as share of total, 2015-2021
lauryl sulfoacetate (SLSA) and disodium lauryl sulfosuccinate (SUS). Whilst these materials are perfectly acceptable cleansing agents, they all have at least one limitation, be it skin feel, foaming, mildness, naturality, etc. More telling, maybe, is the fact that most of these surfactants rarely appear in classic liquid shampoo formulations.
Whilst shampoo bars are increasing in
popularity, there is a definite compromise for consumers with regards to performance. Generally speaking, shampoo bars are purchased due to ethical considerations rather than enhanced performance. Of course, there will always be examples of consumers who prefer their chosen bar due to the subjective nature of shampoo performance. The current shampoo bar market is buoyant
and growing, as has already been indicated. There is, however, likely to be a plateauing of this trend without any real advances in the formulations themselves. Notwithstanding performance issues, the consumer is becoming more reticent about the use of ingredients with perceived issues around them, including sulfates, palm, synthetics, ethoxylates, etc. Some of these perceptions are not necessarily based on the soundest scientific arguments, but it is the nature of our industry that many brands will adopt ingredient selection policies which prohibit any number of useful surfactants. This is problematic with such a limited number of available and suitable surfactants for shampoo bar formulation.
New technology J. Rettenmaier & Söhne (JRS) was founded in 1878 and has a long history of working with cellulose and microcrystalline cellulose fibres. The use of these fibres as pharmaceutical excipients in tabletting because of their binding properties is well documented. They have another useful property of oil and water absorption, because the fibre structure is perfect for absorbing liquids. This property has been used successfully in many applications across a wide range of industrial sectors. JRS’s innovations team has, over the
past year, been working with these fibres to evaluate their properties for a revolutionary new application. Utilising the fibre’s binding and absorption characteristics, we have looked at their ability to absorb liquid surfactants to create dry powders which can then be transformed into solid bars. Initially two surfactants were selected to
evaluate: SLES and coco glucoside. SLES was selected due to its widespread prevalence in shampoo formulations, which is due to a number of reasons, including cost, good foaming, performance and salt-thickening ability. Additionally, the low water content and paste-like consistency of SLES (~70%) was considered to be a good test of the absorption properties of the fibres. Coco glucoside was evaluated due to its
excellent performance in sulfate-free shampoo formulations. It is a widely used, mild, non- ionic surfactant with good foam and cleansing
www.personalcaremagazine.com 2020 2021
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