Layering?

So normally essences go first, however the snail essence from cosrx isn’t really that watery and since it’s better to have actives closer to the skin, i would recommend going first with niacinamide, then the cosrx snail essence. It’s still fine to do it the other way around though.

I suggest niacinamide serum first, when it absorbs fully, then go for snail mucin.

I personally think niacinamide would be better to be first as it would be most effective closest to the skin :)

First niacinamide then snail mucin

The theory behind layering is going from thin to thick, water to oil. Niacinamide is a water based product. From what I see, COSRX is not water based. It is the most beneficial to start with the niacinamide and go over it with the COSRX :)