In most cases, a pigment is used, and the cost is not high. A few decades ago, the countryside was all careful, and writing and painting never cost much. At present, it is possible for individuals to daub words (advertisements) with paint, which is rare. The purchase and price of specific pigments can be asked in the surrounding countryside. I used to go to the countryside to help with this kind of publicity, but the pigments were all provided by the village, and some colors were made by the village itself. for reference only