How do I prepare and apply the yellow clay as a face mask, and how long should I leave it on?

Place 1–2 teaspoons of the clay in a non-metal bowl and add lukewarm water gradually, stirring with a wooden or plastic spoon until you get a smooth, spreadable paste about the consistency of yogurt. Apply a thin, even layer to clean skin, avoiding the eye area and any broken skin. For normal to oily skin, leave the mask on for 10–15 minutes, or until it begins to feel tight but is not yet cracking. If your skin is dry, sensitive, or you are using clay for the first time, start with 5–7 minutes and rinse while the mask is still slightly damp — letting it dry completely can pull too much moisture from the skin. Rinse thoroughly with lukewarm water, using gentle circular motions to benefit from the light mechanical exfoliation as the clay particles lift away. Pat the skin dry and follow with your usual moisturiser or a few drops of facial oil. Use once or twice a week; more frequent use can compromise the barrier, especially on thinner skin.