Why does grey hair turn yellow with keratin and nanoplasty
## Why Does Yellowing Occur?
- Grey or porous hair is more sensitive to heat, which can oxidize residual pigments in the hair or products, leading to yellow or brassy tones.
- Heat can also react with minerals in the water or hair, particularly if the client has hard water buildup. This buildup can leave residues that turn yellow when exposed to heat.
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