It's painted on with something called indelible ink, meaning it can't be removed easily.

它是用一种叫做不褪色墨水东西涂上去，这意味着它不容被擦掉。

And you can see how this process generates very little runoff and produces a colorfast pigment without the use of any chemicals.

你可以看到这个过程如何产生非常流，并在不使用任何化学品情况下生产出不褪色颜料。