Kaolin in China Clay and that's basically most of what this product is. QH makes two masks, I just like the one with the weird minty smell and the sulfur for any potential problem pores.
Wash your face to remove excess oil before applying. Also, make sure you've eaten and that you're hydrated so you don't try screwing your face up to drink, etc.
A reasonable layer will draw unwanted substances from the pores. If you're doing a home-spa treatment and you've finished the bath and the lotions, and you're going to relax for a half hour or something, put on a thick layer, put a fan on your face and let the thick layer dry while you relax and hold your face still. If you leave this on overnight, you will wake up looking really rejuvenated... and the drying process with the fan feels great.
((It's a little silly to walk around with a deadpan expression all night, but if your significant other doesn't mind, or you're single, I think you'll be surprised at how smooth and fresh everything looks in the morning.))
Leaving the mask on for an hour does the pore stuff. Leaving it on overnight does something else I can't quite explain. Do whichever you want. After it's off, slather on a good night cream and don't use anything exfoliating for three days. Scrubbing the mask off is enough abrasion for a while.
I like to use this product twice per month if I have the time.
p.s. If you leave it on overnight, put your hair up/away and cover your pillowcase with towel or use one you're ok with tossing in the hamper. It does flake off if you go to bed with it on and smells a bit odd.
Enjoy. It's a bargain.