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Exfoliating Agents Selection

The process of exfoliation allows for cell turnover, which in essence is the removal of the old to make way for the new. Since regular exfoliation of the skin assists in anti-aging plus removes impurities and dead cells, the use of exfoliating agents has seen a rise in the past years. This guide will help you identify physical and chemical exfoliants, their features, risks, incompatibilities, etc. It would also talk about things to consider while formulating with exfoliating particles. Read on to know more!

Formulating with Exfoliating Particles



While physical exfoliants are less likely to give the formulator chemical problems in a formula they can be equally difficult to work with. What one is trying to do with a physical exfoliant particle is suspend it neatly in a fluid base – to hold it up against the forces of gravity. This is a challenge in itself !


Suspending Power


Viscosity (or thickening power) is not enough to hold back gravitational pull, a formula needs strength or suspending power and we measure that in its yield value – the initial resistance to flow shear applied stress. Yield value is measured in Dynes/ Cm2 . A dyne is a unit of measure that relates centimeters, grams and seconds so the distance travelled in CM by a certain weight over a set time).

The formulator has a choice of many thickeners including a whole range of natural gums and polymers but not all of these will have the yield strength necessary to hold exfoliant particles in suspension for a 30-month shelf-life. While the formulator can get some starting-point help from data sheets and values, getting this absolutely right for what might be quite a complex and unique formula involves experimentation, observation and quite possible a dash of centrifuge analysis!

The particle size, shape and weight of an exfoliant must be considered when selecting an appropriate suspending agent and in a mixed system it is entirely possible that one exfoliant holds while another ‘falls through the cracks’. This is one reason why some formulators choose to use two suspending agents – to form a more complex mesh structure with a synergistically higher yield. Personally I have found that a combination of freeze/ thaw stability and centrifuge analysis helps to short-cut the R&D process in selecting the right suspending agent.

In a cream based formulation yield value is often achieved through a combination of the emulsion structure as given by the emulsifier and any structuring waxes plus a water-phase thickener. While the formulator should consider the extra burden placed on these structures by the exfoliant particles the chances of failure are much lower.


Additional Considerations

  

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