Glass bottles and jars: How are they made?

In nature, glass is formed when lightning strikes the right kind of sand. Humans have perfected this science after numerous trials and today, glass is shaped into various shapes and forms effortlessly for an endless list of purposes. The main reason behind the popularity of glass is that the material is highly eco-friendly.

Given the current state of the earth, reducing waste and utilization of resources has to be given due importance. Glass can be recycled multiple times, without losing its quality, and hence it is a favorite.

Some of the main ingredients involved in producing glass are soda ash, limestone, and silica sand and under extensive processing, these raw materials turn to glass. Here is a brief guide to answer the question ‘how are glass bottles made

The Manufacturing Process

There are many ways to make glass but to meet the demands, mass production of the material is favored. The manual way of making glass is still popular among artisans and those who make customized glassware. Here are a few processes involved that bring glass into being.

Hot end processes

This is the first step in manufacturing glass. Here, recycled glass bits, limestone, soda ash, and other raw materials are subjected to extreme heat. Under the heat of the furnace, this combination takes a molten form. Following this, molten glass can be quickly shaped into the desired shape before it cools down to a certain point.

If you need to add color to your glass, now is the time to do it. Color is brought to glass by adding carbon, copper, magnesium, cobalt oxide, and many other materials depending on the colors desired. However, before molding the molten glass, it is passed through a refiner to get rid of bubbles, failing to do so will affect the structural integrity of the container.


After refining the glass, there are two ways to mold glass. The first one is the press-and-blow method. It is carried out in an IS machine where a shearing blade cuts the glass into a cylindrical shape. After this, it is pressed through appropriate molds and a metal plunger presses it into shapes resembling bottles and jars.

Another method is the blow-and-blow method, where glass is cut using a shearing blade but instead of passing it around into multiple molds, it is passed directly into the final one. In the final mold, blasts of air are used to blow the glass into its desired shape.


To maintain the shape and the strength of the newly formed glass, it is subjected to internal treatment. With the help of chemicals, the inside of the bottle is made resistant to degradation and the outside is strengthened as well as surface friction is reduced.

While cooling down, if the container is subjected to unequal temperature, there is a very low chance that it will hold its shape. Therefore, to prevent uneven cooling and ensure the strength of the container, it is placed in an annealing oven.

Cold end processes

After the annealing, the glass container is almost ready. The only process left to do is a routine inspection to assure integrity. If any cracks are formed in the container during its time in the oven or on the assembly chain, it is caught and the product is removed before being packed. The packaging of the glass jars and containers is dependent on the purpose the products serve.

Different types of glass

Ever since the discovery of glass, people have been immersed in tweaking the original form of glass to create even better versions of it. There are many ongoing studies to make the glass appear more aesthetic, develop more structural integrity, and even become more eco-friendly. Some of the most popular types of glass are:

  • Annealed or float glass is the most basic form of processed glass. It is clear in appearance and is mostly used for creating other types of glass.
  • Tempered glass is a tougher version of regular glass. It is heat-strengthened and can withstand higher amounts of pressure. Tempered glass has found its use in making windows, screens, glassware, and so on. Interestingly, most tempered glass is fire-proof as well.
  • Frosted glass is yet another colorless version of glass. Made by sandblasting clear glass, it has a foggy appearance. The specialty of frosted glass is that it absorbs most of the UV rays that fall on it but only lets a part of the visible light pass.
  • Amber glass is the colored glass that occurs as a result of impurities being caught in the raw materials. Usually giving the final product a brownish or greenish tint, this is the inspiration behind the colored glass seen today.

Applications of glass

Glass serves many purposes, starting from being excellent home decor to playing an important role in biotechnology. The primary use of glass is in packaging, especially food and beverages.

Glass is considered the safest way to package many products that might degrade containers made out of plastic or paper. Compared to plastic, glass containers are also viewed as safer to store food for children and pets.

It is also stellar building material, both on its own and mixed with other materials. Used to reinforce structures of buildings, construct windows, and provide insulation, glass is a precious building material.

Glass also has taken more important roles in information technology recently. Used in communication networks, producing gadgets, and satellite transmission, glass is an integral part of the field of technology.

Aside from this, glass is a great medium for artists. From showpieces to fruit bowls, the decorative value of a glass bottle and bowl is neverending. Similarly, champagne flutes and cutlery made of glass brings up the elegance factor of any dinner party.

Summing It Up

Glass is an extremely useful material, on both domestic and industrial fronts. Studying this process can help in devising techniques to improve production as well as the quality of glass produced.

With proper recycling of the glass produced, the glass waste on earth can go down exponentially. However, hardly 13% of the waste glass is recycled and the rest forms a part of the landfills across the globe.