Sunny Isle Extra Dark Jamaican Black Castor Oil Sunny Isle Extra Dark Jamaican Black Castor Oil ($9) is one of the most common kinds of sealing oils. It normally has a thicker consistency (which means it works best on thicker hair), and it's used by many as a way to strengthen hair while also promoting hair growth and fighting flaky, itchy scalp. Image Source: target.com Sunny Isle Extra Dark Jamaican Black Castor Oil $9 from target.com Buy Now