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Scientific Consulting, Consumer Care, SGS proderm

On 5/31/2022 the proderm publication 'Confocal Raman spectroscopy is suitable to assess hair cleansing-derived skin dryness on human scalp' appeared in the Skin Research & Technology magazine. Stephan Bielfeldt, Vice president Science and Consulting, and Dr. Iryna Kruse, Director Customer Relations & Sales, played a leading role in the development of the method. In this interview, Stephan Bielfeldt goes into the background of this publication and explains why the use of the method can be useful in the development of rinse-off products.

Hi Stephan - the publication published in Skin Research & Technology is based on a new method developed by proderm. Why is this method important?

First of all, I would like to mention that hair products such as shampoos and conditioners are used by consumers worldwide and consequently the hair care market is a significant market in the cosmetics sector.

At the same time, it is known that products from this sector can cause itching, feeling of tension and dry scalp if they are not mild enough. It is therefore essential for manufacturers to answer the question of how mild their own product is.

We believe that up to now there have not been enough meaningful and authentic methods available to answer this question by investigating the effects of hair washing at corresponding area: the scalp. That is why we were very motivated to develop this method and to publish the results.

You speak of a methodological gap to date. Could you elaborate a bit?

Investigations of the scalp are special because of the hair. Methods that work great on other areas of the skin experience difficulties because of the hair that is in the way. This has led to rinse-off products often being examined on the forearm.

However, this approach neglects the fact that the scalp is different from other skin areas. For example, the blood circulation and the thickness of the stratum corneum of the scalp are different from those of other skin areas.

With the method established, we can close this gap and measure product effects directly in the application area: the scalp.

You mentioned hair as a disturbing factor for instrumental measurements. How do you overcome this challenge in your method?

It is important to know that a single hair is about 100 times thicker than the laser used for the measurement. In this respect, there is sufficient space to place it directly on the scalp. During the measurement, our study staff can use a live microscope image to make sure that they are really measuring on the skin and not on a hair.

What exactly is being measured?

The usage of rinse-off products leads to a washout of substances that keep the skin moisturized. These include the natural moisturizing factors (NMF), urea and lactic acid, and barrier lipids. As a result, the skin becomes dry and barrier damage can occur. In conclusion, this means that the less washing out of these substances occurs during product application, the milder the product. It is precisely these factors that we can investigate with the method.

The publication is based on a pilot study. Which product was investigated?

In the pilot study, a standard shampoo, which does not contain any special care substances, was applied to the scalp three times in succession by study personnel.

Isn't that a bit unusual - consumers wouldn't wash their hair three times in a row, would they?

We deliberately chose multiple applications to illustrate the effects of washing out. In fact, we assume that corresponding wash-out effects already occur after a single wash. Moreover, multiple usage is not at all unusual. For example, hairdressers often wash twice. Furthermore, many consumers wash their hair every day nowadays, which is also a multiple application, albeit at longer intervals.

The new method in the context of claim verification - how would that work?

For claim verification, a comparative study with a benchmark or standard shampoo would be useful. Manufacturers would thereby learn how their product washes out moisture-related substances compared to another product.

In addition, a use study can determine whether the product is well accepted by consumers or whether undesirable reactions such as scalp dryness, feeling of tension and itching occur.

Stephan - thank you very much for the interview.


The publication is available as an open access article at the following link:


Contact person

Stephan Bielfeldt

Senior Expert Science & Innovation

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