Each hair colour is given a number, which tells us two things:
- The depth of the colour – also known as the level or base.
- If there are any tones in the colour and what they are.
The depth number is usually separated from the tone number by a dividing symbol like a decimal point, a slash or a hyphen. For example, 4.6, 4/6, 4-6 all say the same thing as far as the ICC goes. A 4.6 translates into plain English as “a medium brown base with a warm red tone”.
However, not all hair colour brands use the ICC and just use an in-house numbering system. For instance, letters may represent different tones, like R for red, or M for mahogany and V for violet.
Even if a brand does use the ICC system, the finished colour can vary from product to product. It means that one brand’s number 4.15 could look slightly different on the hair to another brand’s 4.15.
It’s not a perfect system, but the ICC goes a long way to trying to standard how we define hair colouring products.
