Cosmetics in general are a very personal thing and it is hard to work out why a person would like one product rather than another. It is hard to even work out why you like it yourself. And this is particularly the case with colour cosmetics like foundations. What is it that makes one foundation great and another totally unsuitable for your skin, and why will somebody else come to a completely different opinion?
I don’t tend to use much in the way of colour cosmetics myself so when I get people getting in touch to ask why a product they like is so good, I have often never seen the product, don’t have any idea what it is like and only have an ingredient list to go on. So there isn’t much I can give in the way of on answer. But I have been intrigued by the number of people asking me about MAC Pro Longwear Nourishing Waterproof Foundation.
So I did the only thing I could and looked at the ingredient list and online reviews to see if there was anything obvious about it that made it stand out. Well, there was one interesting thing but lets have a look at how this formulation works first. Here’s the ingredients
Aqua/Water/Eau, Dimethicone, Methyl Trimethicone, Dimethicone Silylate, Butylene Glycol, Neopentyl Glycol Diheptanoate, Phenyl Trimethicone, Polymethyl Methacrylate, PPF-12/SMDI Copolymer, Lauryl PEG-9 Polydimethylsiloxyethyl Dimethicone, Tocopheryl Acetate, Sodium Hyaluronate, Lecithin, Caffeine, Triethyl Citrate, Methicone, PEG-10 Dimethicone, Laureth-7, Silica, Magnesium Aluminum Silicate, Triethoxycaprylylsilane, Polysilicone 11, Xanthan Gum, Sodium Chloride, Dimethicone/PEG-10/15 Crosspolymer, Disteardimonium Hectorite, Caprylyl Glycol, Hexylene Glycol, Zinc Stearate, Disodium EDTA, Phenoxyethanol, Potassium Sorbate, Sodium Dehydroacetate [+/- Mica, Titanium Dioxide (CI 77891), Iron Oxides (CI 77491), Iron Oxides (CI 77492), Iron Oxides (CI 77499)].
Quite a lot going on there even for a cosmetic chemist to work out. But one thing is reasonably clear straight way. This is an oil in water emulsion. So basically it is water with small oil droplets dispersed in it. You can see that water is the first item on the list. It also contains some solid particles of pigment – the titanium dioxide and iron oxide at the bottom of the list. Almost all the oil is in the form of silicone. Silicones are often waterproof, so that is wear the waterproofing claim comes from.
So when you apply this to your skin it spreads out and you have applied a waterproof coating to the skin along with some pigments that give it the colour you are looking for. So that isn’t too complicated.
But the interesting bit was that people who use the product report that the colour changes after a period of time. Some said 25 minutes. This is something they are used to and they call it oxidising. Well I suppose there could be something in there that is oxidising. I can’t see any obvious candidates for it, but molecules don’t always behave how you would expect when you put them in complex systems.
But I think that there is a more obvious explanation. When this product is spread onto the skin it will be spread out into a thin layer. The next thing that will happen is it will start to dry out. As it does so, the silicone droplets in the emulsion will get closer to one another. Eventually they will join up. I think it is that which is giving the colour change. So having done so the waterproof film will be complete. I think that there will still be some water left, but it will be trapped. So you will have a water in silicone emulsion rather than a silicone in water emulsion.
If I am right that is probably the key to what makes this foundation so popular. You are getting a good waterproof effect without actually using too much of the greasy silicone material.
The roles of the actual ingredients are not much to comment on. Sodium hyaluronate is a good moisturiser, but this isn’t the best way to deliver it. Caffeine probably does very little if anything. Sodium chloride is not something you see in this kind of product too often, but when you do it is a clue that someone has been adjusting the formulation to get the optimum droplet size – which if I am right about it being a silicone in water emulsion that flips over to a water in silicone emulsion makes sense. It won’t be there at a very high level and shouldn’t have any effect on the skin. There are 4 preservatives in the formulation. This probably doesn’t sound like it, but I think this is good news. Preservatives work well together and you can usually use a lower total level of preservative overall than if you try to rely on one or two.
So overall, an interesting product from a formulation point of view and one that seems to meet with approval from a reasonably large number of consumers.