What does calligraphy use to write the scarlet letter?

Generally speaking, calligraphy uses black ink, but like the inscription in front of the work, it can be written with vermilion. Beautiful and retro. Generally speaking, large-scale calligraphy works can be written like this. Ancient emperors also used cinnabar to play. Later, for the calligraphy works that have been drawn up, once measures are found, cinnabar can be used to change them. The price of cinnabar is more expensive than ordinary ink. Usually you just buy a small bottle and adjust it at present.