Dry Shampoo

about 12 months

Do not add bicarbonate of soda
Almost every DIY recipe online suggests bicarbonate of soda, and it is bad advice. Its pH is around 9, while hair and scalp are happiest between 4.5 and 5.5. Repeated use lifts the hair's outer layer, and the result is dry, dull, strawy hair that ironically goes greasy faster.

Clay and starch are both close to neutral and do not do that. You get exactly the same absorbency without the bill.

Put it in at night, not in the morning. It is the best piece of advice I can give you and it changes everything. The powder gets the whole night to absorb and distribute, and when you brush it through in the morning there is no white film left, only clean, matte hair with volume. It is also why you can get away with far less.

Dip the brush in the powder, tap the excess off against the rim of the jar, and work it down into partings at the roots. Not onto the scalp, at the roots. Wait two minutes, massage it in with your fingertips, then brush thoroughly with a natural bristle brush. The brushing is not optional, it is what distributes the powder and removes the rest.

About rain, honestly: clay does not run like cocoa, because it is mineral and does not dissolve. But no dry shampoo powder is waterproof. Get properly soaked and it goes. The real fix is to use as little colour and as little powder as possible, and you do that by putting it in at night.

Brush thoroughly every time. What causes trouble with daily use is not the powder itself, it is the layer of powder and sebum building up on the scalp, which can irritate the follicles.

Do not let dry shampoo replace washing indefinitely. It is an extension, not a substitute. If you get flakes, itching or small spots on the scalp, wash and give it a round with the scalp oil instead.

Avoid breathing the cloud. Use a brush rather than shaking the pot over your head, and keep your face out of it. Fine mineral dust has no business in your lungs.

Light pillowcases: with coloured powder in your hair, expect a little transfer the first night. A dark pillowcase solves it.

Shelf life: about 12 months in a dry jar with a tight lid. The powder must never get damp, neither from the bathroom nor from wet fingers.

The colour, and this is where it is won or lost
Start with no colour and add half a teaspoon at a time. Test it on a parting each time you have stirred, and stop one shade lighter than your hair. Powder always looks darker in the bowl than it does in the hair. Write down what you ended up with, or you will never hit it again.

Light, grey or white hair: no colour at all. Kaolin is pale enough on its own and mattifies an oily root beautifully.

Dark blonde: 1 tsp yellow French clay.

Light brown: 1 to 2 tsp rhassoul clay, the Moroccan one. It is naturally greyish brown and hits this shade almost unaided.

Dark brown: 2 to 3 tsp rhassoul plus a small pinch of activated charcoal.

Black: 1 tsp rhassoul plus 1/4 tsp activated charcoal. Charcoal is extremely strong, go slowly.

Red or copper: 1 to 2 tsp red French clay. If you want to keep the cinnamon scent from your old recipe, add a pinch, but use it for the smell and not as the colour.

Very oily hair: flip the ratio, 25 g arrowroot and 30 g kaolin. Clay absorbs more than starch.

Very dry or curly hair: go up to 45 g arrowroot and down to 10 g kaolin, and add 5 g fine rice bran or extra arrowroot. That makes it milder.

No clay in the house: arrowroot alone works, it is just more visible and needs harder brushing.

To scent it a particular way: stay at 8 drops in total, but mix freely, for instance 4 rosemary and 4 ylang ylang.

Arrowroot powder, 35 g (Maranta arundinacea)
The absorbency. Arrowroot is extremely fine and soaks up oil without feeling chalky, which is why it beats cornstarch in hair. It also gives that silky slip that means your hair does not just go matte, it gains volume at the roots.

White kaolin clay, 20 g (Kaolin)
The workhorse. Kaolin is the gentlest of all the clays and a far better oil absorber than starch alone. It is what lets you use half as much powder, and less powder is the entire secret behind a dry shampoo nobody can see.

Rhassoul clay, colour and function (Moroccan lava clay)
Two things at once. Rhassoul is naturally greyish brown and matches most mid-tone hair colours surprisingly precisely, and it is also the clay Moroccan women have washed their hair with for centuries, because it binds oil and dirt. It is mineral, it does not dissolve in water, and so it does not run.

Activated charcoal, for dark hair (Carbo activatus)
Only for very dark and black hair, and only in pinches. Charcoal is so strong that a quarter teaspoon too much turns the powder grey-black and visible on your pillowcase. In return it is the only colourant that can genuinely match black hair.

Essential oils, 8 drops (Chosen for your hair)
The scent, but a little more than that. Rosemary for the scalp and hair growth, peppermint if you want it to tingle and cool, lavender if your scalp is stressed, cedarwood if it is oily. Eight drops in 60 g is plenty, and more makes the powder clumpy.

A small ritual, if you like
There is something good about brushing your hair properly in the morning. Not raking through it with a brush in one hand and your phone in the other, but a hundred calm strokes from scalp to ends, the way women did for hundreds of years because it was the only hair care there was.

Rosemary belongs to the Sun and to memory. So if you put rosemary in, let it be a morning thing: brush your hair, and remember who you are before the day tells you otherwise.

And if it is simply a Tuesday you could not face washing your hair, that is fine too. That is what dry shampoo is for.