Monday, August 16, 2010

Esters: Isopropyl palmitate

Isopropyl palmitate is related to isopropyl myristate (IPM), the difference being IPP is derived from palmitic fatty acid (C16) and IPM is derived from myristic fatty acid (C14). (Click here for the chemistry of esters!) Since we're a little more familiar with IPM, we'll end up contrasting and comparing the two at some point, so here's some information on IPM (original at this post). Both are generally derived from coconut or palm oil.

Isopropyl myristate or IPM (C17H34O2) is considered a short chain ester that feels dry on our skin and won't impact the foam in our surfactant mixes. It's an astringent emollient that can be used to reduce the feeling of greasiness in our products. It's used as a penetration enhancer to help our active ingredients diffuse into our skin better or more easily. It works well as an anti-tackiness ingredient, reducing residue on our skin from our products (like the whiteness from a deodorant or the soaping effect of a lotion). It's a low viscosity ester with a lowish surface tension, so it's considered a very good spreading ester. It has low to no odour, so it won't have an impact on your fragrance choices. Use it at 1% to 5% in your creations.

Isopropyl palmitate or IPP (C19H38O2) is considered a short chain ester that feels dry on our skin and won't impact the foam in our surfactant mixes. It's an astringent emollient that can be used to reduce the feeling of greasiness in our products. It's used as a penetration enhancer to help our active ingredients diffuse into our skin better or more easily. It works well as an anti-tackiness ingredient, reducing residue on our skin from our products (like the whiteness from a deodorant or the soaping effect of a lotion). It's a low viscosity ester with a lowish surface tension, so it's considered a very good spreading ester. It has low to no odour, so it won't have an impact on your fragrance choices. Use at 1% to 5% in your creations.

Huh. Interesting. So they're pretty much the same? Both have HLB of 11.5, both are very good spreading, non-greasy feeling emollients, and both are used as anti-tackiness ingredients. So why use IPP?

Comedogenicity. Both IPP and IPM are considered comedogenic with a rating of about 4 - very comedogenic and possibly acnegenic for some skin types - but IPP can be less comedogenic when mixed with other oils and esters.

IPM used neat has a comedogenic score of 4, very comedogenic. Mix it with something like mineral oil at any ratio, and it remains about a 4. IPP starts off as a 3 to 4 when used neat or at up to 50% of a creation. But mix it with mineral oil - 1% to 25% IPP - and the comedogenicity drops dramatically to around 1.3.

Why is this? I've done a ton of reading and I've found nothing that helps me understand why IPP is less comedogenic than IPM. My guess is that it has something to do with the original fatty acid - myristic acid is more comedogenic than palmitic acid - but I can't say this for sure!

Having said this, having 1% to 5% of a comedogenic ingredient likely won't make you break out. On your face, if you have really acne prone skin, this small amount might be enough to cause some trouble, but few of us will find it problematic for our body skin.

So in general, IPP can be used in place of IPM for most creations, but you might want to consider using IPP if you're making a facial product or for sensitive skin!

Join me tomorrow for fun formulating with IPP and IPM!

6 comments:

Meaue said...

I am loving this series and just soaking it all in. You're doing all the research for me! And explaining it in layman terms! I am actually starting to understand! Thank you so much - keep it up - I am very, very interested!!

Sarah deHebreard said...

Hi Susan,
Are there any specific references you can cite for the reduction of comedogenicity of IPP when mixed with other oils? (like a book or published paper?) I'm using IPP in a body oil and would like to have the full text with this info available in case someone asks!

Thanks!

-Sarah

Anonymous said...

IPP from palm oil is a larger cut. Possibly 45%. IPM from fish oil or other source is a much lower percentage. Hence, IPM is usually significantly more expensive. As an FYI, IPP was used during WW2 as "bug Juice". I believe it's because bugs can't get a good hold on skin coated ith IPP.
I believe Avon Skin So Soft contained IPP and developed a reputation as a bug repellent.

Jane T said...

Both IPP and IPM are off-gased by melanoma cells. Do you have any idea why?





J Biomark. 2015; 2015: 841245.

Published online 2015 Feb 23. doi: 10.1155/2015/841245



PMCID: PMC4437384

Biomarkers for Detection and Monitoring of B16 Melanoma in Mouse Urine and Feces

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4437384/

and see Table S1

Thanks very much,

Jane Teas

Bell said...

I came across your site trying to do research on this new lipstick craze (the jelly lipstick with the real flowers in them) that change colour as you wear them - They don't wear off and don't transfer. If you ever have time, I'd love for you to look into those and post your findings! I found what they claim is the ingredients list but some of the things aren't coming up in google!
Either way, awesome blog!

Susan Barclay-Nichols said...

Hi Bell. Could you post a few links to examples with complete ingredient lists?