The 41-year-old star revealed to Redbook that although she loves her tresses as red as she can possibly get them, her true hair colour is nothing like the barnet she's now known for.
"Little did she know she opened a can of worms. I still love my hair as red as I can get it!"
Her love of hair dye certainly wasn't helped by her teenage days working in a hairdressers as a shampoo girl.
"I worked at [in a campy French accent] Alexandre de Paris in Fairfax," she confessed to the mag. "I scrubbed heads, made perm solutions, put in rollers, and swept up a lot of hair."
The actress also revealed, that unlike many of us girls who can't live without a lick of mascara, she just won't go without a bit of bush.
"I always have on blush, even when I'm not wearing anything else," she said. "It makes me look alive. It's the first thing I put on when I wake up, and [my husband, actor Geoffrey Arend] just thinks I have naturally flushed cheeks!
"I like Make Up For Ever cream blush; it blends into my skin really nicely."
"I have a drawer full of lipsticks," she admitted. "I try everything, though reds and corals are my favourite colours. Nars Velvet Matte Lip Pencil in Pop Life, which is an orangey red, is a nice mix of both."
And finally, Christina's favourite fragrance? The one that really gets her into character? "Fresh's Cannabis Rose," yes, really.
"I spray it on before I go to work. Years ago, Janie Bryant – our show's costume designer – and I began putting Joan in a lot of dresses with roses on them and we realised, Joan is a rose girl."
If you fancy smelling like Christina then you too can own her spritz for $88 (or about £51 to you and me) from here.
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MORE! How to get flawless skin a la Ms Hendricks...