The duration for which bleach, when mixed with a 20 volume developer, remains on hair is a critical factor in achieving the desired level of lightening. This timeframe dictates the extent to which the bleach lifts the hair’s natural pigment, influencing the final color outcome. For instance, leaving the mixture on for too short a period may result in an insufficient lift, leaving the hair brassy or orange, whereas excessive exposure can lead to damage and breakage.
Employing a 20 volume developer offers a balance between lightening power and hair integrity. This strength is often chosen for achieving subtle lightening, blending grays, or for use on finer or more delicate hair types. Historically, the understanding of bleach and developer interaction has evolved, leading to more refined application techniques and a greater emphasis on minimizing damage while maximizing desired color results. This approach ensures a healthier outcome and reduces the risk of compromised hair structure.