The past several months have seen a surge in new acid treatments for the face. Malin + Goetz, however, has taken those same skin-sloughing ingredients like salicylic, lactic, and glycolic acids and put them in the Malin + Goetz Detox Scalp Mask (£28). Unlike the scalp scrubs that contain gritty bits that you apply in the shower and can take some effort to work into your roots, this treatment is a gel that you massage onto a dry scalp and leave on for five minutes. While sitting on your scalp, the gel turns into a foam as it gets to work exfoliating away dead skin cells, breaking up grime and product build-up, absorbing excess oil, moisturising (thanks to safflower, olive, and coconut oils), and soothing (thanks to spearmint leaf and peppermint oils). Why would you want all of that? A healthier, happier scalp means fuller, bouncier-looking hair in the long run.