How to reduce the friction irritation in physical frosted products？
In body care, facial cleansing, and functional exfoliating products, the physical scrub system always occupies a very important position.Compared with acid skin rejuvenation or enzyme keratin conditioning products, scrubs achieve the removal of old waste keratin and the immediate improvement of skin sensation through direct contact between particles and the surface of the skin. Therefore, it has a stable market demand in body scrubs, hand care creams, foot care products and some cleansing creams.
However, in the actual formula development process, R&D personnel often encounter a very core problem: products with obvious frosting effect are often accompanied by a strong sense of friction and irritation.Consumers are prone to feedback issues such as “shaving”, “dry hair after washing”, “redness after use”, and “rough skin” during use, especially in facial care products. This kind of problem will directly affect the product repurchase rate.
The first reaction of many formulators is to solve the irritation problem by reducing the amount of scrub particles added, but in fact, the friction irritation does not come entirely from the particles themselves, and more importantly, whether the emulsifying system can form an effective buffer layer during use, reducing the direct mechanical friction between the particles and the skin.It is often not the particles that really determine the advanced feeling of the scrub, but the emulsified structure.
This is why walnut shell granules, apricot kernel powder or natural plant frosted granules are also used, and there will be very obvious differences in the sense of use of different brands of products.
The nature of friction stimulation
From the perspective of formula structure, the stimulation of physical frosted products mainly comes from three aspects：
The first is that the particle suspension system is unstable.When the frosted particles are unevenly distributed in the paste, the particle density in the local area is too high, which will cause friction concentration during use and directly increase irritation.
The second is that the emulsifying system lacks a lubricating buffer layer.If the cream quickly loses structural support after contact with water, the particles will directly rub against the skin at high intensity, and there is not enough oil phase for lubricating transition.
The third is the lack of residual membrane sensation after washing.Many scrub products have a significant dryness of the skin after rinsing. In essence, the system lacks the ability to form an effective emollient film, which leads to accelerated moisture loss in the stratum corneum.
Therefore, the core of reducing irritation is not to simply reduce particles, but through a reasonable
Oil in water emulsifier system design, so that the cream can stabilize the suspended particles during use, but also form a soft enough skin cushion.
The structural logic of a mature scrub system
Taking a typical oil-in-water scrub as an example, the formula structure is usually divided into four parts：
Phase A is an aqueous phase system, including basic moisturizing and thickening components such as pure water, glycerin, and capo.Among them, glycerin is usually controlled at about 5%, which is used to provide basic moisturizing ability, and carbone is about 3%, which is used to improve the initial viscosity and suspension ability of the system.
Phase B is the core oil phase system, including ethylhexyl stearate, olive oil,
Emulsifier system and auxiliary stabilizer.
Among them：
NSOAF™2EHS usually adds about 8%, which mainly provides excellent spreading and dry and silky skin feeling, while improving the lubricity of the system.
Olive oil is about 5%, as a natural emollient oil, it improves skin softness and comfort after washing.
OILREE® MY6530 (glyceryl stearate se) is about 2%, which serves as a self-emulsifying stabilizer and auxiliary emulsifier to help the system establish a stable emulsified structure.
OILREE® MY9200 (peg-20 stearate or cetearyl alcohol) is about 3.5%. As the core Oil in water emulsion, it is responsible for forming a stable and structurally supportive emulsion network.
Phase C usually adds anticorrosive system and triethanolamine for pH adjustment.
Phase D adds physical scrub particles such as walnut particles to achieve the final exfoliating function.
What really determines the skin feeling experience is not the final particles added, but the overall structure of the emulsifier and emollient system in Phase B.
Why can cetearyl alcohol significantly improve the skin feeling of scrub products?
Many R&D personnel's understanding of Cetearyl Alcohol is still at the level of thickener, but in fact, its value in the scrub system is much more than thickening.
As a fatty alcohol structural agent, Cetearyl alcohol's biggest role is to help the emulsified system form a layered liquid crystal structure.This structure can form a more uniform oil distribution layer on the surface of the skin, so that the frosted particles do not directly touch the skin during the friction process, but slide on a soft lubricating film.
This sense of sliding determines whether consumers will feel that the product is shaved.
Especially in the MY9200 system, the synergistic effect of peg-20 stearate or cetearyl alcohol can significantly improve the system's hot and cold stability, viscosity stability, and particle suspension ability, while giving the paste a brighter and more delicate appearance.
Why Glyceryl stearate se is a key adjuvant in scrubs？
If MY9200 is responsible for establishing the main structure, then MY6530 is responsible for optimizing the softness and subsequent skin feeling of the entire system.
Glyceryl stearate se itself is a very classic self-emulsifying emulsifier, which has the dual functions of a stabilizer and an emollient improver.It can not only assist in stabilizing the entire emulsifying network, but also form a thin moisturizing film on the surface of the skin after rinsing.
This sense of membrane is very critical.
Many scrub products dry out after washing, not because of excessive cleansing, but because the system does not leave enough emollient residues.The protective film formed by MY6530 can effectively neutralize the dryness after physical scrubbing, so that the skin remains soft and not tight after rinsing.
This is especially important in body scrubs and hand care creams.
In some high-end formulas, R&D personnel will also match a small amount of
MYRISTYL MYRISTATE to further enhance the silky feel and structural fullness of the cream, so that the product presents a more advanced creamy feeling during the process of taking the cream and pushing it away.
Why is ethylhexyl stearate an undervalued lubricating core?
Many people think that reducing irritation mainly depends on emulsifiers, but in fact, the oil system also determines the final sense of use.
2EHS usually accounts for 8% of this system, and its effect is far more than ordinary
Emollients.
It has very excellent spreadability, fluidity and dryness, and can significantly improve the friction path between the particles and the skin.Compared with high-viscosity heavy esters, 2EHS does not bring a heavy and greasy feeling, but provides a more advanced dry and silky feeling.
It can also help incompatible oil phase and aqueous phase components form a more stable milky system and improve the overall system stability.
This is why many high-stability scrub systems give priority to it as the main emollient oil, rather than relying solely on vegetable oil.
In some formulas that need to further improve the stability of the system, a small amount of
SODIUM ACRYLOYLDIMETHYL TAURATE COPOLYMER will also be combined as a structural auxiliary polymer to enhance the particle suspension capacity and avoid the problem of sinking after long-term storage.
How to judge whether a scrub system is truly mature？
A mature scrub system does not look at the number of particles, but at the following dimensions：
First, whether the particles can be evenly suspended for a long time without significant sedimentation.
Second, whether the paste has good ductility, and whether the particles are smooth when pushed away.
Third, whether the skin is soft after rinsing, rather than tight and dry.
Fourth, whether the system remains stable at high temperature, low temperature and during transportation.
Fifth, whether the appearance of the product has a high-level sense of fineness, brightness and uniformity.
Behind these indicators, it is essentially the emulsion structure that determines the result, not a single raw material that determines the result.A truly excellent formula is never based on the amount of addition, but on the reasonable structure.
From product experience to raw material selection
MY9200 provides structural stability and advanced skin-feeling appearance.
MY6530 provides a soft film feeling and comfort after washing.
2EHS provides a lubricating path and a silky sense of extension.
Cetearyl alcohol assumes the skeleton role of the entire buffer structure.
These raw materials are not simply superimposed, but work together in a complete Oil in water emulsifier system.The way to truly reduce the irritation of physical frosting is not to make the particles less, but to make the system smarter.This is also the most central direction in the future research and development of scrubs.
Hubei Mingya New Material Technology Co., Ltd.
