The production process of glass jars involves several steps. First, the raw materials such as quartz sand, soda ash, limestone, and feldspar are crushed and pre-processed. The wet raw materials are dried, and any iron-containing materials are removed to ensure the quality of the glass. The batch is then prepared for melting.
The glass batch is heated in a pool kiln or pool furnace at a high temperature ranging from 1550 to 1600 degrees Celsius. This heating process melts the batch and forms a uniform, bubble-free, and liquid glass that is suitable for molding. The liquid glass is then poured into molds to create glass products of desired shapes, such as flat plates and various utensils.
After the glass products are molded, they undergo heat treatment processes such as annealing and quenching. These processes eliminate or induce stress, phase separation, or crystallization within the glass, thereby altering the structural state of the glass.
Glass jars are produced for various purposes and have different requirements based on their applications:
- Food glass jars: These are used as packaging containers for food and must meet national hygiene standards. They need to pass food commodity inspection and have airtight bottle caps. If high-temperature sterilization is required, the glass jar must be able to withstand temperatures of up to 130 degrees Celsius.
- Gift glass jars: These are used as packaging containers for gifts and have aesthetic and decorative purposes. The shape of the glass jar is important, and there are strict requirements for the material, with better transparency desired.
- Medical glass jars: These are used as packaging containers for drugs and medical equipment. The glass jar needs to have light-shielding properties, and the bottle body is often colored brown, green, or black. Medical packaging certification may be required, and they are also commonly used in glass torches.
- Chemical test glass jars: These are used for chemical experiments and testing equipment. They have specific capacity requirements, and the caps must have anti-corrosion properties.