
What is Protein?
Protein molecules are made up of small repeated building blocks called amino acids. As the name denotes, an amino acid is a chemical compound containing an acidic, as well as a basic group, in the same molecule.
The protein that's found in our hair is called keratin. Sulfur-rich cystine is the main component of keratin. Cystine is the backbone of hair structure as it is involved in disulfide linkage in the keratin helical structure and this bond is the one mainly responsible for the mechanical strength of hair fiber.
So, long story short, protein is what makes your hair strong.
What does the protein in hair products do?
The use of heat, chemicals and even environmental stress can cause the disulfide bonds in our hair to weaken. When this happens, the cystine amino acid is converted into a more water-soluble derivative called cystic acid. This means that the amount of cystine in hair decreases while the total amount of cystic acid increases significantly. The presence of cystic acid at the hair shaft makes hair brittle, rough, and more hydrophilic (water-loving). This protein degradation will result in hair that is higher in porosity, having more frizz and more difficult to manage.
The goal of the protein in your hair products is to effectively replace the protein in your hair that's been eroded. Think of it as a method of coating, filming or adding a layer of reinforcement to the individual strands - they penetrate the hair, aligning its cuticles, and fill the empty pores inside the cortex. Or, at least, that's the goal.
But, here's the thing - Not all proteins will accomplish this goal. Different proteins have different molecular weights and are therefore absorbed differently. As a general guide, the proteins bond best to the hair are said to have a molecular weight of 1000 daltons or less. At this size they are weakly cationic (an ion having a positive charge and moving toward a negative one) and can most effectively bond to the hair. If the molecular size of your protein is very large and not broken down at all (like those commonly found in food) it many not be very beneficial to the hair in the long run. For example, simply taking a whole egg and applying it to the hair may not do anything very lasting to replace lost proteins.
pH also is also a factor. Proteins bond well to the hair when they are found in products between a pH of 4 and 7, with 5 or 6 being the most effective.
And, finally, if you have hair that is fine in diameter, generally speaking, a medium to large protein can give you the strengthening and conditioning effects you are looking for. If your hair is more coarse, smaller proteins are more effective. And speaking of diameter, fine hair typically requires protein more regularly than its coarse counterpart. Protein deprivation in fine hair can often come across as a dry/unmoisturized feeling. What most girls with fine-textured curls are really feeling is protein deprivation instead of lack of moisture. Conversely, if your hair is coarse, it's, by nature, stronger than fine hair. Therefore, it doesn't need protein nearly as often as fine-haired curlies.
So, why might you think you're protein sensitive?
Now that you have a good understanding of what protein is, why it's important to have in it in your hair products and how it is or isn't absorbed, let's discuss some reasons why your own experience with protein might have been less than desirable.
Using heat on natural/curly hair is usually viewed as a bad thing. However, to best ensure that your protein treatment absorbs, bring out the hooded dryer, heat cap or steamer. This is especially important if you're low porosity! Otherwise, the protein molecules will just hang out on your hair shaft, unable to penetrate, causing a slew of undesirable or ineffective results.
Until February,
Adria
Credits
https://themestizamuse.com/how-does-protein-relate-to-hair-porosity/
https://hair-therapie.com/blogs/news/does-your-hair-need-protein
https://www.curlynikki.com/2011/09/curl-whisperer-on-protein-friend-or-foe.html