Curly hair – the science behind it
Hair is quite a complex matter. A hair fiber consists of three parts: Medulla, Cortex, and Cuticle (see Figure 1).
The cuticle is the outer layer. It is made of Keratin (a protein) and has a protective function. This layer protects the hair against water loss and also is responsible for the appearance of the hair. The cuticle can be closed or it can be raised (see Figure 2). The preferred scenario is a closed cuticle! This way the hair can retain the moisture and will be soft. If the cuticle is raised, the hair will lose water and it will be dry and brittle.
The next layer is the cortex, it contains Melanin which defines the color of your hair and is responsible for the kind of hair you have – straight or curly. The inner layer is the Medulla. This layer is responsible for the hair color tones, it is generally present in long thick hair. Interestingly it is not always found in the hair shaft.
Now that you have learned the basics about the hair structure, let’s talk more specifically about curly hair.
Without the proper care wavy and curly hair is often dry and breaks.
Why is that so?
Natural sebum is produced by the sebaceous glands present on the scalp. Its function is to lubricate the hair and the skin, and to keep the moisture on it, it is our natural conditioner. The curly hair structure does not allow the migration of the natural sebum along the hair until the hair tip. The curlier the hair, less or no sebum will present further away from the roots. Then water easily evaporates and the hair becomes dry. In addition every hook is a point of weakness – the hair often breaks there.
Curly hair needs extra water and sebum to stay moisturized and strong. Sebum is composed of triglycerides, diglycerides, free fatty acids (together 50 – 60%), wax ester (20 – 30%), squalene (10 – 16%), cholesterol (2 – 4%)  and also vitamine E . A good Leave-in Conditioner contains these components and is able to deliver and deposite them on the hair. To also act as a moisturizer a Leave-in Conditioner may contain water, water based extracts like aloe vera, or hygroscopic substances like glycerin.
The HAVANA CURLS Leave-in Conditioner has been carefully designed by including water based extracts, hygroscopic substances and a large number of other natural components that mimic the natural sebum. This complex formulation provides everything curly hair needs: moisture, softness, strength and shine.
 E. Camerra, M. Ludovici, M. Galante, J.-L. Sinagra and M. Picardo. In: J. Lipid Res. 51 (2010), pp. 3377-3388.
 K.R. Smith and D.M. Thiboutot. In: J. Lipid Res. 49 (2008), pp. 271-281.