The blister industry is an emerging plastic processing sector without dedicated technical standards. Hence, there is no universal criterion to judge whether a product is qualified. Conventionally, the bulk production sample submitted to the customer at last serves as the benchmark. If the finished product differs from the sample in appearance or function — deteriorated appearance including transparency, surface smoothness, flatness and cleanliness; or failure to meet functional requirements such as hardness, loose or shrunken cavities — it will be defined as an unqualified blister product.