When purchasing samples, first smell them for peculiar smell. Some of them do not meet the national sanitation standards and will affect normal use. There is no taste to check its clarity, clarity, uniformity, or impurity, etc. Food bags, food packaging bags The stability of aluminum foil bags is divided into two types, which are consistent with stability and hot air. The stability level of different materials is different, the main method of distinguishing is to align the edge of the bag and tear it by hand. Vacuum packaging bags, tea packaging bags made of nylon and high-pressure film are composite bags, which are generally difficult to tear by hand, and contain heavier products such as semi-foreign objects and large particles. Light product; after the bag is torn open, look at the shape and structure of the cross-section. If the heat seal of the bag is torn evenly in the middle, it means that the heat seal of the bag is poor and the production process is easy to break. If the edge is torn, it means the heat seal quality is good; The composite stability of the food bag depends on how many layers there are in the crack and whether it can be separated by hand. If it is not easy to separate, it means that the composite stability is good. Whether there are bubbles or wrinkles on the surface, etc. Observe the flatness of the bag, the higher the better. For example, nylon and high-pressure film are compounded into a packaging bag. There are waves at the heat seal, and whether the cut edges are neat, the neater the better. Composite packaging bags, plastic packaging bags For the printing quality of aluminum foil bags, see the actual picture, the higher the level, the better. Check whether the bag has zipper, fog version, blocked version, missing printing, etc. If this happens, it means that the printing requirements are not standard.