I’ve been asked this a lot and I don’t have the answer. Most research on skincare application is done with just one product. Sunscreens are always tested on clean skin with no other products. If you want to get as close to the protection on the label, it’s best to recreate the conditions it was tested on, which means applying it on clean skin and not following it with anything else. The same applies for most cosmetic products as well.

That’s not realistic for everyone and many of us enjoy using multiple products. But the reality with a lot of the advice found online and from experts is that it’s just advice and often isn’t based on evidence – especially scientific evidence.

A group of Chinese researchers performed an experiment looking at the effect of different combinations of three products (moisturizer, toner, and mineral water sprays) and different application routines on skin moisture. Keep in mind that the only endpoint measured was stratum corneum moisture measured by the Corneometer, a capacitance measuring tool often used in cosmetic research. This experiment doesn’t provide any insight beyond skin moisture, like skin penetration of an active affected by combination or routine, for example.

20 female volunteers participated in this experiment. Eight 3-by-3 cm squares were drawn on the legs and forearms of each volunteer and were randomized to receive eight different routines and combinations – including a square with no product applied, acting as a control. The baseline moisture levels of the squares were measured and categorized into ‘normal’ or ‘dry’ by a limit of 35 a.u. (a measurement unit used by the Corneometer).

The 8 different combinations and routines are as follows;

Toner and Toner reapplied every 2 hours (T-T)
Cream then Toner together (C+T)
Toner only (T)
Cream only (C)
Cream then Water reapplied every 2 hours (C-S)
Untreated (Control)
Cream and Toner reapplied every 2 hours (C-T)
Toner then Cream together (T+C)

Stratum corneum moisture levels were measured every 2 hours, including a baseline, and participants were kept in a 22 °C room with a 50% humidity.

The products included in the test were a Winona brand Cream with the ingredients:

Aqua, Glycerol, Butyrospermum Parkii Oil, Dimethicone, Glycereth-26, Tridecyl Trimellitate, Pentylene Glycol, Hexyldecanol, Sucrose Polystearate, Diethylhexyl Cyclohexane, Petroleum Jelly, Tocopheryl Acetate, Prinsepia Utilis Royle Oil, Portulaca Oleracea Extract, Beta Glucans, Sodium Hyaluronate, Cetylhydroxyproline Palmitamide, Alpha Bisabolol, Cetearyl Alcohol, Hydrogenated Polyisobutene, Acrylamide, Acrylamide/ammonium Acrylate Copolymer, Acrylates/c10-30 Alkyl Acrylate Crosspolymer, Tween 20, Xanthan Gum, Disodium Edta, Polybutene, Polyisobutene, Butyl Stearate, Stearic Acid, Phenoxyethanol, Ethylhexylglycerin

a Winona brand Toner with the ingredients:

Aqua, Pentylene Glycol, Glycerol, Glycereth-26, Trimethylpentanediol/adipic Acid/glycerin Crosspolymer,
Portulaca Oleracea Extract, Beta Glucan, Sodium Hyaluronate, Hydroxyethyl Cellulose

and Avene Thermal Spring Water was used as the Mineral Water Spray.

While applying any form of skincare product created an increase in skin moisture in dry and normal skin, some combinations were significantly more effective than others.

Table VI is mislabeled and is the data for Dry Skin

Because the normal or dry categories were determined by Corneometer, there’s no way to self-categorize unless you have a Corneometer handy.

From this experiment, the increase in moisture from Cream then Toner, or Toner then Cream, or Cream only were about the same. This implies that the total amount of cream and toner applied is more important than the order of application. As well, this also implies that the increase in moisture is mostly from the cream and not the toner.

The researchers speculate that the increase in moisture reaches a peak depending on factors like the environment which slowly declines after application. Toner on its own did increase moisture of the skin, but even when combined with cream never surpassed the moisture gained from cream alone.

In terms of supplementation of Cream with Water or Toner, the greatest increase in moisture was achieved with application of a Cream then Toner every 2 hours. Supplementation of Water after Cream application reduced skin moisture with each application. Toner with additional Toner supplementation increased skin moisture over time, but was still less than Cream and Toner.

I think reading descriptions of the effects is likely a bit confusing, so I encourage you to use the interactive charts to compare different applications.

Also keep in mind that this experiment used three specific products and concentration of ingredients will vary between products. So it’s best to use this information as a guideline, but not a rule.

Li Yuanxi, Wei Hua, Lidan Xiong, Li Li, Comparison of Skin Hydration in Combination and Single Use of Common Moisturizers (Cream, Toner, and Spray Water), Journal of Cosmetic Science (2016), PMID: 29394018

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Cosmetic Chemist Spotlight: Stephen Alain Ko and the Formulation Revolution

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This machine can help you identify organic materials based on signals from carbon atoms. Carbon-13 nuclei have a “spin”, and this machine can read signals produced after the nuclei are subjected to a strong magnetic pulse.

This is just one of the techniques we can use to identify and test the quality of material. Unfortunately a piece of paper from a supplier saying the material is of high quality…just isn’t enough! As cosmetic chemists we have our clients’ health and skin as our responsibility, so it’s important to make sure that the material going in to our products are what they’re supposed to be, as pure and high quality as possible, and pathogen and contaminant free.

The FDA recently reported a fungal contamination of eye shadows from a small company, as well as unacceptably high levels of lead in a bentonite clay product – marketed for babies.

Sure, it’s a little bit of time and money spent on doing your own quality control….but can you put a price on your clients’ trust and health?

Yesterday I had some samples of hyaluronic acid tested. I wanted to make sure that the material was of high quality, free of heavy metal contaminants and pathogens, and was actually hyaluronic acid

I’ve heard horror stories of suppliers (and repackers) passing off other material as more expensive material. One person told me that they had received an order of product and only the top layer was what it was supposed to be! The rest of the container was just cheap filler!

There’s only one way to prevent these kinds of oversights… and that’s constance vigilance…in the words of Alastor Moody!

And it’s not just the cosmetics industry…Consumer Reports did an experiment a few years ago and found that only 20% of the fish they bought at restaurants and markets were actually the labeled species

"Using a Carbon-13 NMR for quality control…" on KindofStephen.

Sadly the company is no longer in business and this is probably one of the last prototypes sitting around. As a testament to its storage ability I think this one is almost 9 years old!

Here’s the original press release announcing the product:

Poly-D’s MDS patented pump and valve dispensing mechanism allows for easy, one-handed dispensing of an exact amount of product with viscosities up to 50,000cps.

The vacuum-based technology means the pump forces it out of the pouch (98% of it) in a neat and clean manner, and because it is a vacuum-based technology, it works in any orientation.

The MDS valve only opens when the button is pressed and then seals tight upon release, eliminating the need for caps and closures.

It can be used as a stand-alone dispensing package or integrated into applicators or custom-designed devices.

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