Final answer:
Water and oil are commonly used in an oily skin mask to regulate oil production and keep the skin hydrated.
Step-by-step explanation:
An ingredient pair commonly used in an oily skin mask is water and oil. Oily skin masks are designed to help control excess oil production and keep the skin moisturized. Water helps to hydrate the skin and maintain its natural moisture balance. Oil, on the other hand, can help dissolve and remove excess sebum from the skin without stripping away essential moisture.
By combining water and oil in an oily skin mask, you can create a balancing effect that helps to regulate oil production and keep the skin hydrated. Examples of oils that are commonly used in oily skin masks include jojoba oil, tea tree oil, and grapeseed oil.