Professional hair dye, or hair color as industry professionals prefer, is a mixture of the target color and a processor: usually peroxide. Normally, the ratio for the mixture is 1:1.
Professional hair color is only available to salons and cosmetology professionals with a valid license. To mix the dye, both the color and the developer must be measured. Depending on the color brand, cosmetologists mix them either in a bottle or a bowl. Some brands, such as Goldwell, require the use of special bowls and bottles due to the product nozzle.
The processor is normally a peroxide solution at 10, 20, 30 or 40 percent, depending on how much lighter the target color is than the patron's natural color. The higher the peroxide percent, the greater the lift of color. However, semipermanent colors, or those that wash out after several weeks, take a processing solution without peroxide. Semipermanent colors do not lighten the hair.
Cosmetologists first determine the patron's natural color and compare it to the target color to decide on the level of peroxide. The color and peroxide get mixed in a suitable applicator that includes accurate measuring marks, which are normally in cubic centimeters. The color must be mixed thoroughly, either through shaking the bottle or by stirring with an application brush. Bottles have nozzles for application while bowls require the use of an application brush.