Glass as a Sustainable Packaging Solution

We come across glass everywhere in our daily lives. The line of sight wanders in the room. There is a glass of water and a carafe on the table. There is a vase and a glass lantern on the windowsill. I’m also looking through a glass window. There is a glass-top coffee table. There is a framed photo on the wall. Next are glasses, shower doors, and thin fibre optic cables. After thinking about the glass for a few minutes, I look at the clock and see the time through the glass.

Glass is so diverse that it is used in many areas. What is glass? Why is glass transparent? How are the different colours created? Why is glass sustainable and well packaged?

1. What kind of glass is there?

Glass is made from natural materials. In addition to the three main components, it contains a lower proportion of quartz sand, soda and lime, dolomite, feldspar, and potash. They are mixed, heated, cooled, and moulded.

When the heat of lava, lightning, or the impact of a meteorite melts the sand, glass can form naturally. Therefore, it can be called a natural product.

Classification by type of glass can be based on composition, manufacture, or processing method.

Hollow glass, commercial glass, container glass, container glass, flat glass, tubular glass, and fibreglass are distinguished according to the type of use or manufacturing process.

Soda-lime glass, lead glass, and borosilicate glass are subdivided according to their chemical composition. They account for 95% of glass production. 5% are special glasses. Soda-lime glass is displayed in the form of bottles, cups, or flat glass. It is translucent and has a smooth surface, so it is easy to clean. 90% of the glass produced worldwide is made of soda-lime.

Crystal glass is used for drinking glasses, vases, bowls, ashtrays, and ornaments. It has a high refractive index and is easy to decorate. Some crystalline glasses used in the manufacture of industrial glass also contain lead. The percentage is less than 0.5%. 

Borosilicate glass is extremely durable and can withstand high temperatures. Used in laboratory equipment, pharmaceutical packaging, high-power lamp jars, and household casserole dishes. 5% specialty glass includes individual manufacturing for technical and scientific purposes. This includes optical glass, electrical engineering glass, and glass ceramics. 

2. Glass is a natural product Look at history. 

The glass was made by nature before the glass was made by people. Natural obsidian made of rock glass was created by a volcanic eruption after the lava had cooled. Quartz glass is also formed in the event of a lightning strike on the sand. The impact of the meteorite turned the rock into a glassy projectile. 

People used this material for tools, spearheads, and jewellery. Such discoveries date back to around 7000 BC.

The first artificial glass object dates back to 3500 BC. They were glass beads. The soda-filled lime sand formed a layer of glass on top of the clay pot in the overheated oven. It was probably a coincidence. 

Further, 2000 years later, the Egyptians developed the first hollow glass by immersing the sand mold in liquid glass and molding the resulting hot glass layer into a container. 

1st century BC Blown glass was discovered using pipes. Glass plates for windows have also been known since this century. 

The production of glass was a craft for a long time before industrial production began. In addition to Friedrich Siemens’ improved furnace and temperature control, the machine gradually took over the production of glass. The first glass machine was introduced to the market in 1903, allowing nine bottles to be fully automated in one minute. Currently, depending on the machine, about 200 to 400 bottles are produced per minute. 

3. Today’s Glass Manufacturing 

Mechanical glass manufacturing takes place in six steps. 

1. Raw Material Weighing and Mixing: Depending on the composition of the glass, the raw materials of the final product are weighed and mixed evenly in a mixer.
2. Heating: The mixture is heated to 1200 ° C in a glass melting tank. Sodium oxide, calcium oxide, and silicon dioxide combine due to the high temperature to form molten glass. 
3. Purification: The next step is to heat the mixture to 1450 to 1650 ° C. During this melting process, gases such as CO2 are generated. It is released, and the air forms bubbles.

They expand, rise, and are carried away by the melt. 

4. Molding: The glass melt will reach about the temperature. Machine molded at 1000 ° C. 
5. Cooling: The formed container glass is cooled. It takes 30-100 minutes, depending on the type, thickness, and thickness of the glass. 
6. Control and Purification: The glass is inspected and refined for any evidence of defects. These include, for example, spraying, printing, matting, and labelling. 

In addition to the raw materials, the processed cullet is also placed in a melting furnace during glass production. Waste glass is the most important raw material component in the container glass industry.

4.  How does the colour of colourless to colourful glass come about?

If the glass was made in nature, it was coloured. It does not mean that it is colourful and beautiful, but various components hurt it. So it was a big step when people lived in Alexandria around 100 AD. Succeeded in melting colourless glass. 

Then the craftsmen consciously began to add certain substances to achieve the colour. Even today, nanometer-sized metal particles are added to the glass melt in very small amounts, about 0.1%. 

Different metals create different colours. Adding iron oxide creates green, turquoise, or yellow. Copper turns glass into blue or red, chromium turns green, cobalt turns glass into dark blue, and silver turns yellow. Gold is first dissolved in aqua regia and then coloured glass ruby ​​red. It is one of the most expensive glass colours in the world.

5. 7 Reasons for Packaging Glass 

 Packaging glass has many advantages. At least seven reasons speak for themselves. 

1. It is colourless so that the contents can be seen. At the same time, it can be aesthetically shaped in production. But it can also be artistically colourful. 
2. The glass is inert. This means that there is no interaction between the content and the package. Therefore, it is perfectly healthy. 
3.  It’s tight. You can’t escape from the inside (such as carbon dioxide), but you can’t invade from the outside either. Glass is suitable for food preservation. 
4. In addition, the glass is odourless and tasteless. 
5. Glass is also evaluated for hygiene. This is because glass can withstand temperatures up to 500 ° C, depending on the type. Therefore, it can be washed even with high heat. 
6. Amber glass does not transmit ultraviolet rays, so it contains photosensitive foods such as oil. 
7. Glass can be 100% recycled as many times as you like, which greatly contributes to the environment. 

Foods are optimally protected in jars, preserving not only nutrients and vitamins but also taste and freshness. With all of this, glass is also valued in terms of sustainability. 

6. Glass Disadvantages 

 Compared to other packages, glass is relatively heavy. This leads to relatively high shipping costs. The glass industry is constantly reducing the thickness of glass. 

Not only can glass be damaged by falling rocks and drops, but it can also be damaged by the effects of temperature. Non-uniform sunlight or selective heating with lamps or spotlights can lead to tensile stress. The heat is not dispersed throughout the glass, only the heated area expands, and the cold area retains its structure. The resistance to temperature changes varies depending on the type of glass. However, when used properly and professionally, the glass retains its shape. Normal soda-lime glass expands as soon as it is heated. Therefore, the hot liquid should be poured slowly.  

A lot of energy is used to make glass. Manufacturing energy can be saved by using recyclable and reusable systems. Increasing the use of reusable systems increases profitability. 

7.  Why is glass sustainable?  

With many advantages, glass is an indispensable packaging solution. It can be used in all industries, from beverages and foods to pharmaceuticals and cosmetics. Glass accounts for 7% of the most commonly used raw materials in the world. 

The sustainability of glass has three pillars: recycling, reusable systems, and weight optimisation. 

100% recyclable means an uninterrupted cycle. 

Part of the cycle is shown in the figure. This includes a recycling step. Old glass is melted and transformed into raw material for new glass packaging. This works many times without compromising quality. For example, all bottles are made up of 60% recycled glass and 90% green glass on average. 

Adjacent cycles are reusable systems. When the glass container is full, it is purchased, emptied, and returned. It is then rinsed, replenished, and sold. This is done 50 times in about 6 years before the glass is recycled. Repeated use saves production labour and energy. 

 In recent years, in addition to the use of waste glass, lightweight glass technology has saved raw materials. 3050% of weight has been successfully reduced. The Schlegel bottle still weighed 600g in 1975, but today it weighs only 345g with the same stability. The lighter the glass, the less energy is used in both manufacturing and transportation. 

8. What Consumers Can Do for Sustainability 

Consumers play an important role in the two cycles of “replenishment” and “recycling” for environmental protection. Without his help, the cycle would be interrupted. 

The first contribution to the environment: Use and return of deposits 

Reusable systems are primarily for bottles but also for yogurt glasses and milk bottles. A deposit must be paid for the returnable bottles that consumers receive when empty glasses are returned. Empty bottles can be taken to the bottler and refilled. Repayment of deposits is economically and ecologically wise. Returnable bottle deposits are typically 15 cents, and beer bottle deposits are 8 cents. For special bottles, the deposit can be high. 

Second contribution to the environment: Disposal of waste glass (correctly) 

In 1974, waste glass containers for waste glass were installed throughout Germany. There are over 250,000 old glass containers in which empty glasses can be thrown. In this way, about 2 million tons of waste glass are collected every year. 

 It is essential to pay attention to colour separation. Subsequent processing of the recovered waste glass is usually fully automated, but colour coding is a prerequisite for returning to the melting process. Adding 50% broken glass to the production of white glass requires 99.7% colour purity. Amber glass can have up to 8% of different colours. The green glass allows a colour ratio of 15%. 

Only container glass such as bottles, tin cans, medicine bottles, and glass cream jars can be placed in a container. If the colour is not clearly white, brown, or green, the glass is in a green glass container.

9.  Not all debris is waste glass that does not belong to the waste glass container? 

Window glass, automotive glass, mirror glass, drinking glass, (lead) crystal glass, and fire-resistant glass such as casserole plates, vases, laboratory glass, Ceran®, and Pyrex® have different compositions and therefore different melting points. They are difficult to classify during processing. Instead, these types of glass should be disposed of in the remaining waste or brought to a recycling centre. 

Porcelain and pottery are also included in the residual waste. As the ceramic particles enter the recycling process, inclusions form on the new glass. 

Energy-saving lamps or other light sources (LEDs) must be disposed of individually in a collection box or recycling centreMouldingmouldedmple rule is that anything that doesn’t fit in the container’s opening doesn’t belong to the container. 

And the lid? 

 It is best to put the lid in the yellow trash can. If you accidentally leave it on the glass, loosen the screw and put it in the glass container. The system sorts closures. 

10. Easy Steps to a Sustainable Road 

Glass scores on many levels. Not only is the content well represented and optimally protected, but it is also impressed with its natural ingredients and recyclability. 

Sustainability is complex and requires everyone to act as much as possible. When the manufacturer decided to use glass as a package, he took a step towards a sustainable path. In addition, consumers are encouraged to recycle the packaging. Both the use of reusable systems and the professional disposal of old glass are small and sustainable steps in our daily lives towards environmental friendliness.