by Nicole Harmon author of Coils & Curls: The Hair Product Handbook

It takes just the right blend of water (for moisture) and emollients (for smoothing) to tame coils and curls. The emollients are the tricky part. Too heavy and they’ll weigh your hair down, too light and you’ll end up with frizz.

To find the right leave-ins for your hair, it’s important that you understand your “strand thickness,” otherwise known as “hair width“, which can be categorized as “fine to medium” or “medium to thick”. When you see those words on a product label, they’re not referring to how much hair you have; they’re describing the thickness of each individual strand on your head.

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The words “coarse” and “thick” are used interchangeably, but they both refer to the size of individual strands of hair.
Your “strand thickness” isn’t determined by your ethnic background. Two women may have similar looking coils, but one woman’s strands might be twice the size of the others. The only way to know exactly where your hair falls would be to visit a trichologist or dermatologist who has a special microscope that measures strand size.

Fine hairs are around 60 micrometers in diameter; thick hairs are around 100 micrometers. However, you don’t need to be that exact. The tell-tale sign of fine hair is thick-looking roots with a thin-looking ponytail. If you have fine hair, you’re likely to have a lot of strands. Those strands look nice and dense near the roots, but as the hair grows longer, the relative thinness of the strands becomes more noticeable.

The strand thickness slightly varies on different parts of your head, so it can still be difficult to decide how to categorize your hair. Don’t worry about getting too specific, you just need a general idea, so you can find products that make your hair look and feel the way you want. Choose your leave-in conditioners and stylers based on the emollients that you see in the top 5. If you think your strands are fine to medium, choose products that contain lightweight emollients. If you think your strands are on the thicker side, look for products that contain heavier emollients. Whether you’re using a leave-in conditioner or styler, you need to be able to distribute the product evenly, from root to tip, without worrying that it will leave your hair looking greasy.

Lighter Emollients for Fine to Medium Thickness

  • Argan Oil
  • C12-15 Alkyl Benzoate
  • Dimethicone
  • Grape Seed Oil
  • Mango Butter
  • Phenyl Trimethicone
  • Soybean Oil
  • Sunflower Oil
  • Sweet Almond Oil

Heavier Emollients for Medium to Coarse Thickness:

  • Avocado Oil
  • Castor Oil
  • Cetyl Esters
  • Cocoa Butter
  • Coconut Oil
  • Jojoba Oil
  • Olive Oil
  • Mineral Oil
  • Shea Butter
  • Sorbitol Esters

It will take some trial and error to find leave-ins that you love. Many products contain a combination of light and heavy emollients. This is a good time to read the rest of the product label, not just the ingredients list. The descriptions on leave-in products usually mention “fine” or “thick/coarse” hair.

Have you figured out your strand thickness? What helped you decide?

Nicole Harmon, Cosmetic Chemist and author of Coils & Curls: The Hair Product Handbook”, is the founder of She has received rave reviews for her seminars on ethnic hair education and science. She’s on a mission to help the Product Junkies of the world save MONEY, sort through marketing HYPE and buy SMARTER! 
Hair Liberty (def.): The freedom to rock whatever style you want, whenever you want. Curly, straight, natural, relaxed, whatever! Free yourself!

This article was originally published on May 2012 and has been updated for grammar and clarity.