My 90-something-year-old nana, who has had bright blonde ... unclear on how long to leave it in, which left some purple pieces in her hair until she scaled back to using it just once a week ...

"Old-money tones are creamy ... like the Kérastase Blond Absolu Anti-Brass Purple Hair Mask ($68). In addition to using color-safe products, make sure you're using a heat protectant whenever ...

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