Kaolin

Kaolin is the white clay that made porcelain possible, and it is named after a hill. Gaoling — high ridge — is a village near Jingdezhen in Jiangxi province where the clay was dug, and the word reached European languages through Jesuit correspondence and stayed there.^[1]

In cosmetics it does something talc does not. Kaolin absorbs. Where talc slides, kaolin drinks oil, so a powder built on it mattifies by taking sebum out of the surface rather than by laying something over it.

Kaolin is a rock rather than a single compound, composed largely of the mineral kaolinite, a hydrous aluminium silicate. It is mined, washed and graded, and the whiteness of any given grade depends chiefly on how little iron it contains.

As a cosmetic ingredient it is KAOLIN, CAS 1332-58-7, EC 310-194-1, and as a colourant it is CI 77004.^[2] The English trade name is china clay, which records the same origin as the word kaolin by a different route.

Kaolin had been worked at Jingdezhen for centuries before Europe had a name for it. What can be dated is the description rather than the practice. In letters of 1712 and 1722 the French Jesuit François Xavier d'Entrecolles, stationed at Jingdezhen, set out how local potters combined kaolin with a ground porcelain stone called petuntse, and gave the proportions used for different qualities of ware.^[3]

The year recorded in this entry is that of the first letter. The gap between when a material was used and when it was written down is real, and collapsing the two is how a dictionary quietly becomes wrong.

Kaolin's platelets are smaller and blockier than talc's, so it gives less slip and more absorbency. In a loose or pressed powder it controls shine. In a clay mask it is the mild option, drawing oil without the tightening pull of bentonite. In toothpaste it works as a gentle abrasive.

It also brings bulk and some opacity, though much less of the latter than titanium dioxide, and it takes pigment cleanly — which matters in a product where the clay is most of the mass.

Kaolin appears in Annex IV to Regulation (EC) No 1223/2009, the European Union's list of colourants permitted in cosmetic products, as CI 77004.^[4] It carries none of the reclassification activity that has recently surrounded talc, and it is not subject to the amphibole contamination question, which is specific to talc's geology.

That is a statement about what is documented, not a comparative safety claim. Kaolin is a mined mineral dust, and what literature exists on it addresses occupational exposure during extraction and milling rather than the finished cosmetics it ends up in.