What Hair Dye Does to Your Hair – The Science

Most of us have dyed our hair at one point or another. Some of us dye it so much we barely even remember what our original colour is! Much of the time we keep do it without thinking about the science, we just book a hair appointment and off we go.

Colouring hair is a great way to refresh your look, get a hotter look, cover greys or do something completely new. Here’s a little information about what dye actually does to your hair and how to keep your hair healthy afterwards.

Ammonia Goes Through the Hair Cuticles

This is no simple stain. The ammonia in hair dye elevates the pH of your hair and lifts the cuticle up to let the molecules of the dye in to set the colour permanently.

Now, you may be thinking but what ammonia-free hair dye? Well, these dyes use a substitute chemical, ethanolamine, which is milder but is far less effective at lightening hair. Meaning that whilst it may be gentler on cuticles you will end up dyeing your hair more frequently.

Peroxide Makes Hair a Canvas

Once the cuticle is broken your hair is ready to be stripped of it’s natural colour pigment using peroxide (commonly known as bleach). Bleaching oxidises the proteins of the hair to leave it colourless. This creates a canvas to prepare your hair for the colour of your choosing. However, this part of the process can really dry our your hair and make it straw-like in texture.

Colour is Added

Once the ammonia and peroxide have worked new colour molecules, monomers, penetrate into the hair shafts. When they are in the react to create larger molecules. Now these polymers are so large that simply washing your hair is not enough to initially lose them. Now, your hair is coloured!

Leaving Dye in for Longer Damages Your Hair More

While you are sitting in the salon chair waiting for your dye to work, your cuticles remain open. While the dye is still on your head the dye is penetrating those open cuticles and hair shafts. The longer the dye is in the more it weakens the hair until your rinse the dye out. However, this still damages the hair. Conditioning treatments that your use after rinsing are to close the cuticles up and lock in that new, delicious colour.