Rele AS, Mohile RB —Journal of Cosmetic Science 2003
Pre-wash oiling limits damage from combing hair. This seems likely if the oil has a linear structure and a low molecular weight like coconut oil.
Disclaimer. I’m not a scientist, but I’ve always had a keen interest in science and understanding the how and whys of how things work. If you find anything inaccurate, please share the feedback so not only can I improve my writing, but prevent misinformation.
Paper
“Effect of mineral oil, sunflower oil, and coconut oil on
prevention of hair damage”
Claim
Pre-wash oiling limits damage from combing hair. This seems likely if the oil has a linear structure and a low molecular weight like coconut oil.
Data
The following diagram highlights coconut oil, mineral oil and sunflower oil’s effect on protein loss before and after wash on undamaged hair.
Coconut oil protects against protein loss due to combing by almost 50%, which is a significant amount in comparison to the other oils.
Interestingly, their way of testing protein damage uses the Sandhu and Robbins method:
“Each of the wet tresses was combed with a fine-tooth nylon comb
(20–22 teeth/inch) 50 times, rather vigorously along the entire length of the tress on both sides.” — p180 J. Cosmet. Sci. (March/April) 2003
Unclear understanding of the experimental method
It is not clear why there is a with and without result for each type of oil. I assumed there would only be 8 tests in total:
- Without any oil, and with the three oils
- The above is pre-wash and post-wash.
However, the test has 12 results rather than 8, and there is variability in protein loss without each oil type as well. For example, I assume the middle bar represents mineral oil and its protein loss without mineral oil is almost double the amount of that found in the test without coconut oil.
Notes
Why does the molecular structure have an impact on protein loss?
Coconut oil is mostly a triglyceride of lauric acid and is hydrophobic. Application of coconut oil as a pre-wash conditioner coats the hair and inhibits the penetration of water into the hair. A small part of it is also absorbed into the hair during the wash when the fiber is swollen. Introduction of this hydrophobic component reduces the swelling propensity of the cuticle, which limits the upward curving of the surface cuticle. This reduces the chipping away of the cuticle cells, which reduces protein loss, as observed in this work. — p191 J. Cosmet. Sci. (March/April) 2003
Potential hypotheses
Vigorous combing is responsible for hair damage, even though pre-wash oiling with oils like coconut oil can help decrease damage.
Even though it wasn’t the point of the experiment, it would be interesting to note the difference between hair damage pre-wash and post-wash using less vigorous methods like finger combing.
However, considering the number of variables of their test, they were already working with 800 experiments down from 14,400.
What is protein loss?
Their experimental method describes it as the weight of debris dislodged from the hair itself after dipping the hair in a solution.
Full Citation
Rele AS, Mohile RB. Effect of mineral oil, sunflower oil, and coconut oil on prevention of hair damage. J Cosmet Sci. 2003 Mar-Apr;54(2):175–92. PMID: 12715094.
Link
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