A lovely client who has trusted my hands for 6–7 years. 🤎 Her hair was once light brown, but repeated coloring at home gradually left it dark brown. Today, I matched her new roots to the existing shade. Why can home hair color turn out darker than expected? The shade number on the box does not tell the whole story. Your starting color, previous dye, hair condition, and processing time all affect the result. Repeatedly overlapping color on already-colored lengths can also cause pigment buildup. My Own Formula Language Read the hair’s history—not just its visible color. Bleaching and repeated chemical treatments can damage the protective cuticle and increase porosity. Color can then enter more readily, sometimes developing darker or less evenly than expected. That same porous structure can also allow color to fade more quickly. Even a lighter-numbered shade can deposit unwanted depth on porous, previously lightened hair. Pro Tip for Hairstylists Strand-test first. Assess roots, lengths, and ends separately, then adjust the formula, application order, and processing time. Toning lightened hair also requires careful formulation: porous ends may take on depth very quickly. Monitor the actual strand result and follow the product’s directions rather than judging by the color of the mixture alone. Today’s approach: touch up the new roots and blend them into the existing brown, without unnecessarily layering more dye over the lengths. The more you understand hair color, the more fascinating it becomes. The same formula can behave differently on different hair. Thank you for trusting me year after year. Enjoy the gentle sounds of real salon work. 🎧 Rhea Jeong | 27 years of hairdressing experience Over 11,500 videos across YouTube, Instagram, and TikTok—personally filmed, edited, and uploaded. 📍 Jeonggain Hair 1st Floor, 507-24 Galhyeon-dong, Eunpyeong-gu, Seoul, South Korea By appointment only. Booking: https://m.place.naver.com/hairshop/1056912285/home YouTube: https://youtube.com/channel/UCFl7c436YpSm_WhC_l2CBiw Instagram: https://www.instagram.com/jeonggain730/ TikTok: https://www.tiktok.com/@rhea.jeong 🇰🇷 💙💙💙 #RootTouchUp #HairColorASMR #PorousHair #JeonggainHair #KoreanHairSalon - @rhea.jeong