In a typical lab you don’t often get much time to just play around. But you snatch the odd moment to indulge yourself from time to time, and I always enjoy spreading the emollient oils on my skin to get to know their individual characters and personalities. One long standing favourite is isopropyl myristate which has a soft silky feeling, a bit reminiscent of velvet.
It gets used quite often in skin creams, particularly premium high quality ones. I have to say that if I am honest I have never really felt that it actually contributes as much to these formulations as it promises to from how it feels neat. Where it really scores is in bath oil formulations. I am a busy man and I usually take a shower to save time, but every now and again I’ll enjoy a bath with a bath oil rich in isopropyl myristate.
Chemically speaking it is a branched ester. All this means is that the molecule is made up of chains that branch out and that it has a particular kind of chemical link called an ester link. There is a whole family of branched esters, notably isopropyl palmitate which is similar to isopropyl myristate and which some formulators prefer. I like them both and I particularly like having a choice. Sometimes you see formulations where quite a few branched esters have been used. In this case it is probable that somebody somewhere has gone to a lot of trouble blending different oils to get exactly the skin feel that they wanted.
Isopropyl myristate is perfectly safe as a cosmetic ingredient and there are no issues with it as far as end users are concerned. It has been attacked by scaremongers either from ignorance or more likely from a cynical desire to sell inferior products at high prices. Any website that suggests this material is harmful should be ignored.
There is one persistent story that keeps coming up, and that is that isopropyl myristate is comedogenic. This issue dates back decades and should have been cleared up years ago. Comedogenic is an ugly word and I would be a lot happier if we used plain english. If you are suggesting that something causes blackheads, it is a lot easier to understand if you just say so. But back to my story. During the sixties several labs worked to try and use tests done on animals to help study skin diseases. This blog is about science not ethics so I won’t comment on the rights or wrongs of the morality. But it has to be said that the science wasn’t great. Rabbit ears were the focus of the study, but for what it showed they might as well have left the rabbits in peace. The problem was that there was very poor agreement between labs even on the results of the tests let alone the interpretation of them. Isopropyl myristate was shown by some labs to be comedogenic to rabbits ears. Others got the opposite. And as to whether this meant that it would cause comedogens in humans, well that was far from clear either. It turned into one of those areas of research where the more papers you read the less you understood what was going on. What I can say is that I have had plenty of isopropyl myristate on my skin over the years and it has never given me a single blackhead.
So all in all, a lovely raw material.
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I am doing quite a few ingredient posts at the moment. You might find this one on potassium sorbate interesting. It is a preservative often used in natural products.
You can find the official information about isopropyl myristate at cosmetics.info.org