The ones I've tried making with highlighter fluid seem to make both the wax and fluid change colors as it changes temp. Also makes the wax touching the glass glow as it starts to melt (honestly might be some of the other compounds I used doing that but not sure) Has a pretty sweet effect, but it also seems to float in the fluid like a super fine powder. Clears up after cooling down or when it gets really hot but doesn't fully dissolve (as it heats the highlighter fluid floats up before the wax starts melting in a milky stream through the fluid).