Using the permanent markers at very low temperatures depends on several factors. If the pen is frozen because it has been exposed to very cold temperatures, this will not harm the pen. Our pens can be stored at -20°C. After thawing, the marker works again. Writing at -20°C is different and depends on several factors. The pen cannot write well when frozen. So cold on cold does not work. If the pen is worn on the body, it is not frozen. So warm" pen on cold material should work.