Many marketers of natural soaps recommend the use of apple cider vinegar in particular as a rinse aid when using their product. And many other web sites and message boards extol its virtues as well. Here, I’ll discuss how best to use vinegar to care for your hair.
The Unique Benefits of Apple Cider Vinegar
Apple cider vinegar is made by adding sugar, yeast, and bacteria to apple cider. This process ferments the cider into an ethanol solution, and then the bacteria convert it into an acetic acid solution. The cloudy and sometimes slimy portion of apple cider vinegar is actually dead cells of bacteria and yeast (yum!), sometimes referred to as “mother of vinegar.”
Apple cider vinegar is highly prized in the natural-products community, both for its reported health benefits and its extra nutrients that can help hair or skin. That may be the reason it is most often the rinse recommended for hair. However, current research does not show there to be any appreciable amounts of vitamins, minerals, enzymes or amino acids present in apple cider vinegar.
Other types of vinegar are made from wine, malt, corn, rice, coconut, sugar cane, or even beer. The pH for all the different vinegars range from about 2.5 to 3.5, depending upon the concentration of acetic acid (and the other acidic byproducts which can occur in the process, such as citric acid and tartaric acid). When it comes to use as a hair tonic or rinse, there really should be no performance difference between any of type of vinegar, so you can pick the one you prefer for reasons of smell or price.
Another excellent application for vinegar is to use it in conjunction with soap/shampoo bars, as a means for the prevention of build up of hard water–induced soap scum, which can be devastating to the condition of your hair.
Vinegar is also just a great pH adjuster for the hair when used as a rinse in a dilute aqueous solution. It is essential that your hair be the proper pH after cleansing and conditioning, as this affects the overall health, appearance, and condition of your hair. For this reason, most modern shampoos and conditioners are “pH balanced,” meaning they are adjusted to a pH very close to that of the hair in its healthiest state.
The relationship between pH and hair
Human is hair is made up of strands of fibers made of keratin protein, which contain the amino acids glycine, alanine, and cysteine. Cysteine contains sulfur, and is responsible for the disulfide bonds in hair. These contribute to the overall strength and elasticity of hair strands as well as to curl formation. Proteins are made up of many amino acids linked together into a chain, and then gathered and folded into other structures. Due to their chemical structure, proteins have the capability to possess either a positive or a negative charge, depending upon the local environment. There exists one pH (at a given temperature), where the molecule is completely uncharged or neutral, and this is known as the isoelectric point. The isoelectric point for human hair optimally is a pH value of 4.0 to 4.5.
Hair that is at its isoelectric point has a tight structure and a sealed flat cuticle layer on the outside of the strand. Things that can raise the pH of our hair are structural damage from processing or rough treatment; use of basic solutions on the hair such as perming solutions, relaxers, or baking soda; and soap bars or soap containing detergents. Hair at a higher pH is negatively charged, and has a more swollen and porous structure. It also has lifted, ruffled cuticles that contribute to a dull appearance, frizzy character, tendency to become tangled, and a higher propensity for breakage.
Since vinegar is acidic, with a pH between 2.5 and 3.5 (depending upon type and concentration), using it in a dilute solution as a final rinse for your hair or as a rinse prior to conditioning is an excellent way to lower the pH of your hair to the isoelectric point or slightly below it. This allows the hair to be sealed flat with a smooth outer layer of interconnected cuticle scales. This has the effect of making hair very shiny, with fewer tangles, more bounce and greater mangeability. To obtain maximum benefit from your rinse, I recommend preparing your solutions from water that has been filtered or softened. It is important to use vinegar carefully and in conjunction with a good conditioner, as it can be somewhat drying to the hair if used frequently or in too high a concentration. Overall, it is a fantastic and affordable addition to any hair-care routine.