Qualified paper cup inner film is of course very uniform, whether it is paraffin or plastic, it should be smooth, which can be judged by the naked eye, and can be seen more clearly with the help of light.
Nowadays, there are all kinds of paper cups. In order to increase their competitiveness and defeat their competitors, merchants will choose to print various patterns on paper cups, but the patterns are not printed randomly. Those with printed patterns within are unqualified.
Paper cups are made of paper, and paper is made of wood. Normally, there will be no peculiar smell. If it smells sour or pungent, then don't choose it, although generally speaking, there is no mandatory shelf life for paper cups. , but it will be affected by wet weather, and it is also possible for the wood to become moldy before it is made into a paper cup.
