100% imported Tung Oil is hard to find. That is the reason your contractor used the Tung Oil Finish instead of 100% Tung Oil. As most things American, and product that has in its Brand Name "Tung Oil Finish" is cheap. It contains harmful VOC's and in some places have been taken off the shelf. By putting in a very small amount of Tung Oil these companies, sell a product that is less than Number one quality.