You can use chalk pens to do writings on all non-porous materials. Furthermore, they are easy to wipe off, and they do not leave behind any stains. A non-porous material or surface is one that does not have any holes. Therefore, it cannot absorb any liquid or gas. On the other hand, porous materials have microscopic holes, allowing them o absorb gas and liquids. Some examples of non-porous materials are glass, metals, and hardened plastic. Even though you can use liquid chalk pens on all these surfaces, it is vital to read the product label because different products are designed for specific surfaces. Using your chalk pens on their intended surfaces will ensure that you receive the best results. If you want a liquid chalk pen for glass, you will have several options as long as you specify your search.