What’s Isopropyl Myristate?
Let’s take a closer look at one of my favourite ingredients of all time – isopropyl myristate (IPM)! This oil-soluble, clear, colourless liquid ester offers light, silky, smooth, soft, non-greasy emollience to anhydrous products (those without water) and emulsions when included in the oil phase. IPM reduces feelings of drag and waxiness, and reduces the amount of effort required to spread a product on your skin. With these awesome sensory characteristics, what’s not to love?
Oh, there are concerns about potential comedogenicity? Let’s take a closer look at this awesome emollient and see what that’s all about!
Benefits of Isopropyl Myristate
Moisturization for Skin and Hair
IPM offers awesome moisturization for skin and hair, especially in those products where lightness or a more matte finish are welcome, or where you don’t want a feeling of heaviness, occlusion, or residue. It’s great for lighter conditioners for fine or oily hair, products that might want some moisturization without feeling weighed down or looking oily.
Non-Greasy, Silky Skin Feel
One of isopropyl myristate (IPM) major claims to fame is the non-greasy – almost astringent – skin feel without that heavy, oily sensation you might get from a natural emollients, even lighter ones like apricot kernel or sweet almond oil. It can reduce the sensation of oiliness of other ingredients in the product, making it feel more silky and smooth, even when used at low amounts of up to 3%.
Enhanced Spreadability
Because it’s so light and leaves behind no residue, it’ll let the lovely “quick break” or sploosh of water come through in a gel or gel-cream product, offering that amazing feeling of hydration and coolness we love in these products. Skin feels fresher, less greasy than it would with a natural oil or butter.
Improving Body Butter Formulations
If you made an anhydrous whipped body butter filled with loads of lovely butters – like cocoa butter, shea butter, or mango butter – or tallow, adding a bit of IPM to the mix can create something lighter, less greasy, and more silky on your skin, reducing the drag we get from those solid-at-room-temperature emollients.
Applications in Moisturizers and Emulsions
We formulate with IPM in moisturizers and other emulsions for these sensory characteristics. You’ll enjoy the lovely light emolliency we expect from facial products, avoiding that cloying feeling when there’s too much occlusion. With increased slip and glide, it reduces the amount of pressure and force you need to apply the product.
Use in Eye Gels and Cosmetics
It’s used in eye gels and eye creams again for that non-greasy, weightless emolliency, so it won’t get all over your eye lashes or in your eyes, forming that greasy film we all hate.
You’ll notice it on the ingredient lists of a lot of colour cosmetics for these sensory characteristics along with its superior ability to wet and disperse colour in eye shadows, lipsticks, foundations, concealers, and other products that contain pigments. The addition of a bit of IPM can help create a smoother finish and more colour pay-off. Even in basic lip balms, it’ll offer a smoother texture than those that are composed solely of waxes, butters, and oils.
Role in Serums
You’ll find it in a body or facial serum, creating a smoother, more luxurious product that’s even easier to apply and achieve excellent coverage.
Chemical Properties of Isopropyl Myristate
From a cosmetic chemistry perspective, IPM is lighter than water at 0.84 grams per millilitre (water, 1 gram = 1 ml) with a low viscosity of 5.5 mPa.s (water = 1 mPa.s). The surface tension is low, and it’s considered fast to ultra-fast spreading, which is why it’s so awesome at increasing smoothness. Esters as a class of emollients are less greasy when compared to natural oils, fatty alcohols, or fatty acids due to these properties.
It’s derived from isopropyl alcohol and myristic acid, a fatty acid you’d find in most of our natural oils, butters, and solid oils, like coconut oil.
Is Isopropyl Myristate Comedogenic?
Understanding Comedogenicity Ratings
With all of these great properties, why might people not like it? The potential comedogenicity? Let’s talk about that.
Comedogenicity ratings have changed a lot in the 19 years I’ve been formulating products. They were originally determined using the Draize test – when products or ingredients were applied to rabbit ears and observed for production of comedones (clogged hair follicles) – which weren’t that accurate because they were more sensitive than those conducted on human skin.
Using these tests, undiluted IPM was given a rating of 4/4 or 5/5, the worst comedogenicity ratings possible using the Draize test. When mixed with 25% mineral oil, the rating went down to 1 – an important point we’ll explore more in a minute.
New Testing Methods and Findings
Tests these days use a new model, the Kligman-Mills model, which tests ingredients on human subjects, applying ingredients to skin on the back or arm. These tests are a bit more accurate, but as you know, tolerance can vary from body part to body part, skin type, ethnicity, follicular size and density, sebum production, hormonal changes, and so much more. It’s hard to say that something applied to your back without issue won’t be comedogenic on your face, which means that although this method is better than the Draize test, it’s not necessarily something you can extrapolate to another part of the body.
The new ratings for IPM’s comedogenicity using the Kligman-Mills model show that at 10% strength, IPM has a rating of 1 to 3, while at 2.5%, it’s 0, meaning it’s non-comedogenic.*
*Reference: A re-evaluation of the comedogenicity concept, Draelos & DiNardo
The Role of Dilution in Comedogenicity
An important thing to note when we’re reading these comparison charts is that comedogenicity is reliant on the concentration of the ingredient. We rarely use any ingredient at full strength – although I’ve been known to slather straight shea butter on my feet after a long summer’s day – and we’ve seen that dilution will bring the comedogenicity rating down.
We’ve seen how adding 25% mineral oil to IPM can result in a lower comedogenicity rating on the Draize test, and we’ve seen how using 2.5% has a rating of 0 using the Kligman-Mills method. This means that at the level we’d find IPM in our formulas – like in the range of 0.1% to 3% – it can be considered to be non-comedogenic on both types of tests. Nice!
Final Thoughts about Isopropyl Myristate (IPM)
Using IPM neat is completely safe. It’ll give you a silky, soft, emollient sensation with a matte finish that’s incredibly easy to spread, but on its own, you wouldn’t get that super hydrating and moisturizing sensation you get from a lotion, body butter, facial moisturizer, or other product we use to make our skin feel gorgeous.
Formulating is all about choosing ingredients with amazing sensory characteristics – combining light, medium, and heavy emollients to create a smooth sensation as you apply it to your skin, a concept called cascading emollients. IPM really shines when we use it as part of the oil phase in emulsions or as part of an anhydrous product.
I hope you’ve enjoyed taking a closer look at this awesome ester, isopropyl myristate (IPM), and why we use it to create incredible, less greasy, more elegant face, body, and hair care products.