What do clay masks do to my skin?

Clay masks don't actually absorb or "soak up" oil, and they can't really "purify" and "detoxify" your pores either. A mask with kaolin (a mineral-rich clay), sea mud, or even charcoal does provide a gentle way of exfoliating by coating the skin like an adhesive. When it dries and is rinsed off, the mask theoretically pulls off some dead cells, debris, and oil with it. It's the same concept as rolling a lint brush over the surface of a sweater. Pore strips work the same way, and they're terrific. Sometimes a clay mask contains active ingredients like sulfur, which is a natural antibacterial and anti-inflammatory, or tea tree oil, a natural antiseptic and anti-inflammatory. But a treatment like this won't be more effective than a salicylic acid exfoliant and diligent nightly cleansing. A clay mask can reduce the oil you have right now, but unfortunately it's just going to build up again in no time.