What is a moisturizing oil? What is sealing oil? Better yet, what exactly is the difference between the two? It all boils down to what the difference between a moisturizer and a sealant is. According to the Mayo Clinic, moisturizers prevents and treat dry skin as they hold water in the outermost layer of the skin. The sealant on the other hand does not bring the moisture to your strands, but just holds it in. The moisturizer brings it and the sealant keeps it there; this also applies to the hair. So in a nutshell (pun included), they are both oils but some will penetrate the hair shaft and induce moisture while others will seal the moisture that is already there.
The power of natural oils
Do not discount the power of natural oils. Whether you are discussing essential or carrier, natural oils bring numerous benefits to our bodies and strands. Essential oils are used extensively in aromatherapy while some are even used by traditional medicinal systems. Carrier oils or base oils are often filled with essential fatty acids that aid in cleaning, skincare, hair care, massage, and even cooking. They are quite often used to dilute the potent essential oils, as they are extremely concentrated. Both carrier and essential oils are revered for their cleansing, aid in moisturizing, sealing and healing either together or separately.
Now, in general oils alone are not moisturizers but there are a few oils that will penetrate the hair shaft and soften the hair from within. So, some oils moisturize while others merely seal. That means some soak in while others just coat the hair. Which is which and why? I had to consult a professional to get more information.
Sister Scientist breaks it down
It takes a real chemist to explain what is going on with oils and their penetration levels, so Sister Scientist was gracious enough to share her knowledge on the subject.
“The level of penetration is determined by the size of the oil molecule and polarity. Coconut oil, being the most penetrable of natural oils, is very high in triglycerides containing short chain fatty acids, making the molecules small enough to penetrate the cuticle layer. It is also more polar (positively charged) than most oils, which makes it more attracted to the negatively charged proteins in hair.
Oils that are more likely to penetrate deeper into the hair shaft include:
- coconut oil
- sunflower oil
- palm kernel oil
Oils that may also penetrate slightly beyond the outer cuticle layer, but are better to be used as oils to seal, coat, and lubricate the hair to prevent moisture loss and increase softness include:
- olive oil
- avocado oil
- argan oil
Oils that contain very bulky lipid chains make the molecules bigger, and highly unlikely to penetrate, but are great to enhance shine and lubrication for ease of combing. They include:
- jojoba oil
- rice bran oil
Best Way to Use Oils
- Moisturizing/penetrating oils: coconut oil, sunflower oil, and palm kernel oil
- Partially penetrating and sealing oils: avocado oil, olive oil, and argan oil
- Sealing oils: jojoba oil and rice bran oil
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Journal of Cosmetic Science, 56, 283-295 (September/October 2005)
Investigation of penetration abilities of various oils into human hair fibers. K. KEIS, D. PERSAUD, Y. K. KAMATH, and A. S. RELE.