Yes, you can use heat on hair chalk; in fact, it's often recommended to help set the color and reduce frizz.
Applying heat styling tools, such as a curling iron or straightener, after applying hair chalk can help "lock in" the color. This process not only aids in making the color last longer but can also help smooth out any frizz that may result from the chalk application process. So, after applying your hair chalk, feel free to style your hair with heat as desired.
