What is the oil painting core was also called the heart?

What is the oil painting core was also called the heart? Over the years, the era of progress, the things people use more and more products are more refined, and modern have an advantage, do not know to ask, ask clear, on the last website up to ask, in here, we talk about, oil painting, painting category to talk about it! Oil painting, painting in general is painted on canvas, and is also a lot of types of cloth, chemical fiber cloth, linen, Brod, cotton, oil paintings of different styles, with different fabrics to paint, to draw should have artistic effect, and in a fabric painting done on a painting, we called oil painting core, also called painted heart.

 
Painting core advantage is that in every exhibition, must exhibit a large number of oil paintings, oil painting frame if you are mounted well, it is not easy to send, that are generally sent painting core.