Fizz is right this is done by using discharge inks. They are an agent that removes color but does not damage the clothing. Once screened a heat source needs to be hovered over the screened image till the image is the color you want it. It will not beach all the way through if you put a light coat on as well. I have many shirts made like this. It is basically doing the oposite of what a dye would do. And it looks great. But it is a lot of work.