Every ingredient, named and explained.

Olive oil has been used on skin around the Mediterranean for about as long as anything has. Here it does the unglamorous work: it carries the cleanser, keeps the bar from drying your scalp out as it washes, and gives the whole thing enough body to hold its shape for a month in a wet bathroom.

You may know it as the plant medieval Europe made blue dye from. In Korea and China the leaf is a traditional remedy for heat and irritation, and that is the reason it is this high up the list. It is not here for colour.

Cebaekyeop, 측백엽, turns up in hair and scalp preparations in Korean medical texts going back centuries. Almost nobody outside East Asia formulates with it, which is part of why this bar smells and behaves differently to whatever you used before.

Two jobs. The oil is in the bar directly, and the surfactant that does the actual cleaning — sodium cocoyl glycinate — is built from coconut fatty acids joined to the amino acid glycine. So the coconut is both an ingredient and the raw material for the ingredient above it.

Shea is the buffer. A cleanser removes oil by definition; shea puts a little of it back on the way past, which is what lets most people skip conditioner for the first fortnight without their lengths turning to straw.

Tea tree is one of the few botanicals in this category with a genuine body of research behind it, and it is also a known contact allergen for a small number of people. If you have reacted to tea tree before, this is the ingredient to know about — patch test on your inner forearm first.

Rosemary is having a moment, and for once the popular ingredient is also the researched one. In a bar it sits on the scalp for the length of a wash rather than passing through in a rinse, which is the whole argument for applying it where it is meant to go.

The name is a story. He shou wu translates as "Mr He's black hair", after the man the legend is told about. Whatever you make of the legend, this is the single most traditional hair ingredient in the entire formula, and it is the one we would keep if we could only keep one.

Japanese and Korean women have used camellia seed oil on hair for centuries, and it is still the oil of choice for fine hair that goes limp under anything heavier. In a bar it means the lengths get something without the roots paying for it.

If one ingredient signals that a formula is Korean rather than generic botanical, it is this one. Ginseng is in Korean skincare the way niacinamide is in Western skincare: everywhere, for a long time, for the barrier rather than instead of it.

Bitter root, used in Korean and Chinese medicine for itching and irritated skin specifically. It is not a famous ingredient and it never will be, but it is one of the reasons comfort is the first thing most people notice rather than anything to do with density.

Reishi is one of the oldest recorded remedies in East Asia and the dark variety is the less common one. Strictly it is a fungus rather than a plant, which is the sort of detail we would rather tell you than have you find out.

Jogakja pods foam on their own — they contain natural saponins, which is exactly why they were used for washing. Finding one in a modern formula is strange, and for a brand selling a bar instead of a bottle it is the ingredient that makes the most sense of all of them.

Sangbaekpi is the root bark, used in hanbang preparations for the scalp. It is at the bottom of the ingredient list, which means there is not much of it — we would rather say that than let the label imply otherwise.