Is it okay to use gypsum powder on the gray background when playing guqin?

It is not good to use synthetic paint and gypsum powder as ash base, and the hardness of synthetic paint is not as high as that of wild paint. In ancient times, antler cream and wild paint were used to make the piano face hard and the sound quality moist, but it took a long time to reach the best state. Ray Wei Yun in the past: 500 years, a positive tone. Tile ash and lacquerware were widely used as substrates in the Qing Dynasty, and the sound of the piano was penetrating, but it was difficult to preserve it for a long time. It is better to use Jingdezhen porcelain ash as the base of modern Pei Jinbao's research. I'm doing an experiment, considering using different ashes to make the next three layers.