Why clay

What clay does, and who measured it

Clay has been put on skin for as long as there has been skin to put it on, which is an argument from habit rather than from evidence. These are three trials we could read in full.

None of them tested an Allura product, and we have not run a trial of our own. Two used clay that had been chemically modified or compounded with other actives, so each result belongs to that formulation and not to clay in general.

The three findings, the methods, the formulations tested and the citations are set out on the home page — numbers first, and each one openable down to the paper it came from.

Why a rock does any of this

The clays in question are smectites, and a smectite is not a powder so much as a stack of silicate sheets. Split them apart and one gram opens out to an enormous surface, and that surface carries a net negative charge. Sebum and positively charged material stick to it. That is the whole mechanism: surface area, porosity and charge.

When we have our own

If we run a trial, it goes here with the lab named. Until then this page is other people's work, cited, with its limits stated.