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Reverse Engineering? There's more to a formula than the INCI list...

Over the last few years, I've noticed a huge shift in how people are thinking about the process of formulating cosmetics. When I started over twenty years ago (yes I know, yawn, yawn) there was an industry-wide understanding that formulating is a creative scientific process, one that involves a deep understanding not only of ingredients but also of proportionality, manufacturing method, compatibility, legality, scaleability and stability to pull off. In recent times, I've seen that shift towards a more simplistic conceptualisation, with many early-career formulators approaching it with 80% focus on ingredients and only 20% on everything else. I also see this focus in the way finished cosmetics are marketed, like if you can only hone in on the product with the ideal INCI list, you'll have perfect skin.

This is my argument against that logic, my argument for why I view the ingredients as only 20% of the formulating puzzle.

Here's a practical experiment outlining my why's and hows.

One INCI list, 4 Serums.

Inspired by the 'turn and learn' philosophy i.e.: turning to the INCI list tells you everything you need to know about a product.

I wanted to offer up a practical demonstration of the limitations of an INCI list and as such, put together one of my own. I then converted that into four serum formulations and made them as you see here:

And here’s an INCI list to cover all four versions:

INCI: Aqua, Rubus Fruticosus Fruit Extract, Glycerin, Niacinamide, Sodium Hyaluronate, Acacia senegal gum, xanthan gum, Phenoxyethanol, Ethylhexylglycerin, Sodium Hydroxide.

What can the INCI list tell me?

These are a fairly simple, water-dominant set of formulas that contain a hefty amount of fruit extract followed by a couple of other well-known dermatology-backed actives (glycerin, niacinamide and hyaluronic acid) in a preserved gel base. There is no fragrance or added colouring, the formulas are fairly natural (except for the preservative) and there aren’t too many ingredients.

Guessing what skin outcomes an INCI list like this might achieve.

I could assume the main function of a product with this INCI list was to rehydrate and balance the skin with secondary functionality around environmental protection. The ingredients definitely support that with glycerin, fruit extract and hyaluronic acid.

Then again I could assume this to be an anti-ageing formula with antioxidant protection highlighted and visible wrinkle reduction/ skin tone evening as second and third functionality. The INCI list supports that too!

Let’s not forget that it could also be a brightening formula! A formula optimised for gentle exfoliation and skin glow (fruit acids, Niacinamide).

Or it could be an all-around face food product, a daily ‘respect your skin’ serum offering gentle, balanced all-around support.

But wait, it may be designed specifically to tackle pimples, marks and oily skin! The INCI list tells us the formula is oil-free so surely it’ll be non-comedogenic. Also, niacinamide is a really good option for pimple-prone skin and break-out management.

And so we go on.

This, my friends, could be many things to many people depending on how these ingredients have been blended together and what the intentions behind it really were. This detail is often found outside the INCI list in the product description, directions for use, claims and product name.

Moving onto the actual formula versions.

Before we go too deep I wish to point out a few things about my INCI list (this is for anyone who likes reading things with a view to nitpicking). There could be other ways of organising and presenting this including ways that would differentiate the variants as I’ll describe now.

Fruit juice powders, Aloe Powder and Coconut milk, water etc are often added to a formula and re-constituted. That is, rehydrated with water to form their full-strength juice. That juice can then become an INCI ingredient in its own right thus reducing the level of ‘aqua’ (boring old water) or replacing it entirely. As far as I am aware it is not incorrect to list these ingredients either as their extract (referring to the powdered ingredient you added), their ‘juice’ (the power plus water to reconstitute it) or a combination of both. I opted for the former to help me make my INCI list point and also because not all powdered plant extracts have these options available so it’s not always relevant. Some fruit, herb or veg powders are not complete and so you can’t ever really end up with the equivalent of a whole fresh juice from them.

I digress but yes there is this…

The second variation to INCI I’ll acknowledge here is in the ordering of the ingredients below 1%. They can go in any order so the one I’ve chosen is not the be-all-and-end-all. That said, it wouldn’t constitute a change in INCI anyway given they are all under the 1% mark.

If there’s anything else that I could have done I no longer care and am moving on (that’s not entirely true but I’ve got to get to the exciting stuff).

The making.

I opted to make these all the same way, cold process with a mixture of propellar and homogeniser mixing before checking and altering pH if necessary then packing off. I purposefully used the same method of manufacture as I didn’t want too many layers in this experiment but I acknowledge that chaging the manufacturing method, using heat, different mixing speeds and times etc would have an impact on the final product aesthetic for better or worse. Again these changes would not have been reflected in the INCI list and are another thing INCI can’t tell us.

The pH.

After just telling you I don’t want to over-complicate things I did do this. I split the batches into two and kept one at a pH of between 4.5-4.8 which is close to the natural pH this formula falls to due to the fruit acids in the Blackberry extract. I adjusted the other half up to 6.2-6.5 using sodium hydroxide (only a few tiny drops or 20% solution were needed per 100g sample) to better optimise the formula for Niacinamide activity. I did this because a) I just can’t help myself and b) you can’t tell the pH from the INCI list and there are plenty of examples where changing the pH can actually change everything with regards to formula stability, aesthetic and efficacy.

The Results:

Top from Left to Right: All pH adjusted to 6.2-6.5, versions 4, 3, 2 and 1.

Bottom from Left to Right: All pH 4.5-4.8, versions 4, 3, 2 and 1.

I didn't formally measure the viscosity but I am sure you can see that there is a clear difference between these versions just by looking at the pictures. This is unsurprising given the variation within the formulas but isn’t something the INCI list would be able to tell you.

You may also be able to see a colour difference. This is not uncommon when the colour of a product is created with natural materials such as fruit powders. The fruit contains a range of naturally occurring pigmented chemicals that respond to shifts in pH by changing colour and that’s what’s happening here – a shift from a pinky purple to a blue purple/ grey. This colour change may or may not signify a change in the functional activity of the ingredient on the skin. We’d have to dig deeper into the chemistry of the extract to work that out.

Below are some other details I noted with regard to these same INCI, different outcome formula versions:

  • I calculated the price per Kg for each version and there was 196% difference between the highest and lowest – so the most expensive was nearly double the least all with the same INCI. Just in case you are interested, the recommended retail price based on the formula ingredient costs for these serums would be between $13.50 and $25.50 per 100ml of product which seems very good value to me – get me some! Oh wait, I already have them..

  • The products at pH 6.2-6.5 would be best for activating the Niacinamide onto the skin but would definitely speed up the oxidation of any vitamin C present in the Blackberry extract. While the pH 4.5-4.8 samples would still lead to loss of vitamin C I would expect it to occur more slowly. If someone were to market this formula they would need to decide what to optimise the formula around noting the Blackberry extract is more than just a blob of vitamin C of course.

  • Focusing on the Niacinamide we have a serum with nearly 3 times as much active niacinamide as another with no INCI list difference. It would depend on what I was claiming for this INCI as to whether that was significant or not.

  • We can’t tell from an INCI list what molecular weight the Hyaluronic Acid is. In a cosmetic setting like this, the molecular weight of the Hyaluronic isn’t as critical as people might believe it to be with regards to its hydration and active delivery capacity. However, the Hyaluronic Acid molecular weight really does change the product aesthetic (viscosity, skin feel, speed to sink into the skin). Too much High Molecular weight HA, especially in a formula that also contains gum, can lead to it balling up on the skin and feeling yucky! Again, you can’t tell that from the INCI but you definitely would notice something off during application!

  • Glycerin (plus the gum and HA actually) changes the osmotic pressure of the formula and the way it acts as a humectant. I wouldn’t expect the same performance, skin feel and osmolality from a product with 3.5% glycerin vs one with 6% glycerin and that could impact the formulations efficacy around skin hydration.

  • Acacia/ Xanthan gum responds to pH getting thicker with decreasing pH to the point it can become quite glue-like. As the tackiness of a formula can be strongly influenced by surface-tension, the lower pH sample feels tackier (more sticky) than the sample at the higher pH. This wouldn’t be obvious from the INCi list and people might assume all the stickiness is from the fruit extract alone which would be incorrect!

  • We can’t tell how stable any of the formula versions are from the INCI. A super trained eye might be able to identify potential problems in some cases and on a few occasions it is more obvious to someone with experience that a formula will perform below par, be unstable or otherwise vulnerable. Even in those situations it’s important to back up the hunches with testing as you actually never really know until you investiate hands on. An unstable product will lead to oxidation or mocribial contamination of the ingredients thus reducing its potential to do good on the skin and potentially making it irritating. So the INCI list can give us an idea around vulnerability but typically not enough to make a solid call. In this case I’d mainly be concerned about UV stability of the fruit extract, the vitamin C degradation impact and any thickening effect over time due to the formula osmolality.

  • The INCI list tells us we have Blackberry fruit powder in the formula but it doesn’t say how the powder is produced, whether it is solvent extracted, hot or cold processed, how concentrated it is (how much you need to add to create a reconstituted juice, or even if it represents the whole dried fruit or just a part of it). This detail may or may not be critical in working out if the product contains the ingredients needed to deliver a particular outcome for the skin. As the specifics around outcome are usually listed outside the INCI list, those focusing only (or mainly) on INCI could make false assumptions about a product or just miss out on this valuable clarrification.

Summarising the state of things.

While I designed this experiment to point out the limits to the INCI-exclusive mindset I’ve been quite surprised at just how far those limits stretch even in a simple experiment like the one I’ve walked you through here.

To re-cap again, this two-part blog fest was inspired by the catch-phrase ‘turn and learn’ which in turn was something I came across on a YouTube beauty channel. The idea behind the saying being that it’s the INCI list that tells you most about a product’s worth and as such, is what we should focus our attention on.

The risk, when critiquing one tiny part of another persons work is that in removing it from its wider context you inflate or exagerate its importance and change the way it was meant to be received. That has not been my intention here, this is not a critique. What this blog post has been designed to explore is merely inspired by that catch phrase, delving into what might unfold IF we took the ‘turn-and-learn’ approach to extremes and took no notice of any other information about the product.

The last bit.

Most ingredients are active across a reasonably large range of input levels meaning they could appear at the start, middle or towards the end of an INCI list and still be functionally active and useful. Even ingredients with a relatively narrow active range can still fall into different slots in an INCI list depending on what else is in the formula. It’s really difficult to tell how relevant the ingredient placing is unless you are quite a skilled formulator and can de-construct and re-construct (reverse engineer) a formula with high accuracy. This is not as simple as you might think as we have ingredients like the Hyaluronic acid – same INCI, different molecular weight and aesthetics; ingredients like the preservative which is a blend rather than individual ingredient and ingredients such as the fruit powder which could change functionality depending on how it had been extracted and what part of the fruit it came from.

Factors outside of the INCI such as the product pH, viscosity, look, feel, smell even can affect how well a product works – you are less likely to use a product you don’t like than one you do and you might use more of something you love than something you don’t have a strong opinion over.

Then there’s the compliance side – has the formula been tested, does it make any specific claims or give you any clues as to what it was formulated to focus on, does it appear stable – how would you tell? Is it likely to have been made to good manufacturing practice standards, does the person who formulated it know what they are doing? So many questions.

Then theres the symphony side. I said in my original piece that cosmetic chemistry is like a symphony with many moving parts, something that’s alive, changeable and responsive to your touch. That type of detail is the X factor in many a formula and can never really be captured in words.

So that, my friends, is that. I hope I’ve made my point somewhat clearer and given you a few things to think about.

INCI is something, not everything and let’s work to keep it that way hey!

Amanda x

PS: I actually made this serum with the fruit powder because I wanted something colourful to look at. The other benefits are interesting too of course and the pH colour change is always a good thing to consider.

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