How often should you color your hair?
How often you color your hair depends on several different variables. One must take into consideration the type of dye being used, the strength and condition of the hair, and the desired color of the hair.
The strength and condition of the hair is the most important factor when deciding how often you should color your hair. Some people's hair can withstand several chemical processes in a single day, while other hair types are much more fragile. Generally, those with thick and coarse hair types can get away with more frequent colorings than those with fine hair. Porosity of the hair is another consideration, as it will affect processing time. Porosity refers to the hair's ability to absorb moisture. Hair that is overly-porous will absorb color faster than hair that is resistant. In order to test your hair's porosity, snip a few strands of hair near the ends and place them into a cup of water. Within a few seconds, porous hair will sink to the bottom and healthy hair will float.
The type of hair dye is another important factor. Most permanent colors contain ammonia, which can be damaging to the hair. Temporary and semi-permanent dyes are much healthier for the hair, but they only have the ability to darken the hair, not lighten it. Lightening the hair is always more damaging than darkening the hair. Provided that your hair is healthy, strong, and has passed the porosity test, hair can be colored with a permanent dye every four weeks. A semi-permanent color, sometimes referred to as a color glaze, can be applied every two weeks if desired.
Hair that is over-porous or dry can still be colored, but less frequently and with more care. Close attention must be paid to processing time, as porous hair can process 5-10 minutes faster than healthy hair. Unless the hair is extremely damaged, dry and porous hair can be colored every 6-8 weeks with a permanent dye and every 4-6 weeks with a semi-permanent dye.
Severely damaged hair should never be colored at home. Only a trained professional will be able to assess the degree of damage to the hair, and will then be able to decide whether or not it is a good idea to apply color to the hair. Signs of severe damage include breakage and excessive hair loss. Applying the wrong type of hair dye or leaving the dye on the hair for the wrong amount of time can result in a hair disaster, which is why it is always best to leave coloring in the hands of a trained professional.