Better than any explanations, this is an educational video produced by Biocoiff and Logona, which explains very well how standard chemical and organic hair colors operate.

This is a summary chart with the main differences between chemical and organic hair colors.

CHEMICAL HAIR COLORING

• Requires prior peroxide bleach, coloration chemically modifies hair pigments.
• Entails a chemical reaction inside the hair.
• Contains (among others) toxic aromatic amines, that can be absorbed by the skin.
• Possibility to darken and lighten hair without limit, fast application.
• Permanently damages hair, both permanent or temporary hair coloration.

It’s a two step process. First of all, an oxydizing reaction with the effect of bleaching the hair. Second, a chemical process giving the hair the desired pigment.

ORGANIC HAIR COLORING

• Organic coloring coats and sheathes the hair fiber,
• Does not cause chemical reaction inside the hair but falls like a veil on the hair.
• Organic hair coloring cannot make the hair lighter in color.
• Long application time,  long lasting coloration.
• Brings more or less deep copper sheen.
• Brings definition, shine and volume. Like stain on wood, it operates with semi transparency creating heavy and natural shades.
• Lacks any toxic and harmful substances.

–> Read the article about organic advantages.