Let’s Start with Sebum!
Sebum is a waxy substance produced by the sebaceous glands and all mammals have these glands. If you were to skip out on washing your hair for a week, sebum is what would cause it to feel and look greasy. Eww, am I right! This is common among mammals.
To get technical, sebum is made from triglycerides, wax esters and squalene — basically a cocktail of long-chain fatty acids and hydrocarbons which work together to create a moisturizing layer that protects your hair and scalp and has waterproof qualities. To break it down even further, fatty acids have a polar end and a non-polar chain. The polar end attracts water while the non-polar side repels water like a stinky teenage boy repels… well, everyone. The longer the non-polar chain, the more hydrophobic the fatty acid.
This is why an emulsion of vinegar and oil will separate almost immediately. But this is also why lanolin helps sheep stay dry when it rains and why we use it in lotions and cosmetics to hold in moisture. Why do we care this deeply about sheep grease?
|Think about this…
For those of us who wash our hair every time we shower, something happens with our sebaceous glands. As we wash the sebum from our hair and dry out our scalp, this tells the sebaceous glands to produce more sebum to protect the scalp. As a result, we overproduce sebum and our hair quickly becomes greasy.
How does lanolin compare to the sebum in hair and fur and why do we differentiate? If we’re honest, there is little difference. Lanolin is sheep sebum, often referred to as grease or wool wax. Generally, sheep produce much more sebum than we see in hairs or furs, but this is not always the case. Some sheep produce very low amounts of lanolin and some produce very high amounts. Different sheep will also produce lanolins with slightly different chemical makeups, which can make the lanolin softer, harder, waxier, or more oily.
The amount of lanolin has an impact on how many times a fleece needs to be scoured before spinning and whether or not it is a good candidate for spinning in the grease.
|Spinning in the Grease
Usually we scour a fleece and remove all the dirt and lanolin before we spin. Spinning in the grease is a term that refers to spinning wool which has not been scoured and still contains its lanolin though it may or may not have been washed to remove dirt. Like stinky French cheese, spinning in the grease is an acquired taste. It allows the wool to retain some of its waterproof qualities and lanolin is great for your cuticles. Spinning in the grease may even be a replacement for manicures! Weird…
Deedrick, D. W., & Koch, S. L. (2011, March 01). Microscopy of Hair Part II: A Practical Guide and Manual for Animal Hairs. Retrieved September 17, 2017, from https://archives.fbi.gov/archives/about-us/lab/forensic-science-communications/fsc/july2004/research/2004_03_research02.htm
Loden, M., & Maibach, H. I. (2006). Dry skin and moisturizers chemistry and function. Boca Raton: CRC Press.
Patton, J. S., Stone, B., & Papa, C. (1984). Solubility of fatty acids and other hydrophobic molecules in liquid trioleoylglycerol . Journal of Lipid Research,25, 189-197. Retrieved September 12, 2017, from http://www.jlr.org/content/25/2/189.full.pdf
Scobie, D. R., & Young, S. R. (2000). The relationship between wool follicle density and fibre diameter is curvilinear. Retrieved September 17, 2017, from http://www.nzsap.org/system/files/proceedings/2000/ab00043.pdf