What is NRP?
NRP means Natural Remaining Pigment. NRP is color theory 101. A lot of clients ask how we as colorists understand how to get from brown to blonde and vice versa. The main thing to understand over everything else is NRP. Here is a little breakdown about what it is and why it is the most valuable tool in the colorists’ tool belt. Without this basic, I mean very basic color knowledge you will never achieve your desired results. Make sure your colorist and you, the client, have the education to back what you are doing as well. The best client to have is the educated client.
The NRP is the tone that contributes to the end color result. It is also important to determine the base tone of the color used in the hair color application. The colorist can refine or enhance the NRP during the hair color application. Coloring hair is always a combination of the natural remaining pigment and the tone that was applied to the hair.
If someone wants to go from Level 6 dark blonde (I consider it light brown) to a Level 10 blonde you have to eat thru 5 levels of NRP. While lifting these levels you must also use a higher level of developer. 4+ levels of lift you would need to use 40-vol developer. When it comes to developer think of them as blinds for a window. Here is my analogy. When you open your blinds a little bit you only expose a bit of light into the room. When you open up a little more, more light and when fully opened you have the most light. Think of this light as warmth within the hair. The higher the volume of developer the more the blinds of the hair are open thus exposing even more of that NRP. While lifting you want to either enhance or cancel out this warmth depending on the desired look.
Hopefully this will help in understanding why hair always looks warmer by coloring, highlighting and also being outside. Sun lightened highlights are the perfect example of NRP being exposed. Dark brunette women usually have red/copper undertones, Light brown hairs expose soft golden blondes and lighter hair exposes those coveted platinum blonde tones. These are all our NRP.