In hair coloring, understanding the principles of the three primary colors ( red, blue, and yellow) is crucial for accurately creating the desired shade. These primary colors form the basis of all colors and can be combined to produce a wide range of hues. This principle is utilized in hair coloring to achieve various tones. 

• Red, blue, and yellow each function as independent colors. When mixed appropriately, they can create secondary colors: orange (red + yellow), green (blue + yellow), and purple (red + blue). 
• When aiming for a specific color in hair coloring, consider the current color of the hair (natural or previously colored) and the target color. For instance, if you want to neutralize yellow tones in hair to achieve an ash (grayish) color, you will need to add blue or purple elements to counteract the yellow. 
• When choosing hair color products, think about which color you want to add to the hair or which color you want to neutralize. Select a coloring agent that contains the necessary primary colors for your goal. For example, to eliminate brassiness (unwanted warm yellow or orange tones in hair), choose a product that contains purple or blue, which are opposite colors to brassy tones on the color wheel. 

By basing hair coloring on the primary colors, you can adjust the color to achieve the desired shade. In addition to understanding the primary colors, knowledge of the color wheel is also beneficial. The color wheel helps visually understand the relationships between colors, showing which colors harmonize with each other or which colors are best for neutralizing others. 

Understanding and utilizing these principles allow for precise and effective hair coloring, ensuring that the desired color results are achieved.