Coding on rigid plastic substrates whose ink adhesion can be difficult. Indeed, lightweight rigid and semi-rigid plastics have replaced glass or metal containers as the packaging of choice for many dairy products, candy, and cosmetics. They are also frequently used for industrial components. These lightweight, durable plastics include polypropylene (PP), polyethylene (PE), and high-density polyethylene (HDPE). While the use of rigid and semi-rigid plastics can reduce shipping and handling costs, the different chemical composition of these plastics can affect ink adhesion or the effectiveness of laser coding.