Sheets used for blister packaging are called hard sheets or films. The commonly used types include PET (Polyethylene Terephthalate) hard sheet, PVC (Polyvinyl Chloride) hard sheet and PS (Polystyrene) hard sheet.

PS hard sheet features low density and poor toughness, and it burns easily. It releases styrene gas (a harmful gas) during combustion, so it is generally used to manufacture various industrial blister trays.

PVC hard sheet has moderate toughness and is not easy to burn. It produces chlorine gas when burned, exerting a certain impact on the environment. PVC is easy for heat sealing and can be edge-sealed with sealing machines and high-frequency machines. It is the primary raw material for producing transparent blister products.

PET hard sheet boasts good toughness and high transparency. It is combustible yet generates no harmful gas during burning, making it an eco-friendly material. However, it comes at a higher price and is suitable for high-end blister products. Blister clamshells in European and American countries generally require PET hard sheet. Nevertheless, it is difficult to heat seal, which brings great challenges to packaging. To solve this problem, a material named PETG (glycol-modified polyethylene terephthalate) is adopted. This material combines the easy heat sealability of PVC with the high environmental performance and transparency of PET, but its price is relatively higher.