Do you have this kind of rice paper (disposable) for practicing calligraphy now? Brush dipped in water, written on that kind of rice paper, will show black characters.

There is a kind of water writing cloth called the five treasures of the study. The base is light gray. When you immerse the brush in water, the words are black. As long as the pen is dipped in less water, it will dry later. It's quite convenient. Stationery stores sell it, and the price is about 10-50. The price is determined according to the packaging and materials. Very practical, you can choose.