The 20 minutes was enough for me for the mask to start working.
I don't wash off the rest of the essence. Instead, I massage it into my face skin. As soon as I used it, I could tell that the skin had become much denser.
The mask helps get rid of dullness and slight puffiness because it has a light cooling effect. Among other things, it gives the skin exactly what it needs. The pores do become less obvious, and bumps and black dots also fade.