Pure vegetable oils like sunflower, almond and olive oil are easily found at grocer stores. They have the property of dissolving the active, fat-soluble active principles of medicinal plants and herbs. This process is called infusion and can be carried out at room temperature or higher. Infusion is a slower process than alcohol extraction but has the advantage of resulting in an oil based solution of medicinal constituents that can easily be used to make creams and ointments. Hot infusion is recommended for the harder parts of the plants while cold infusion is more suitable for flowers and leaves.