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Is All Glass Food-Safe For Making Food & Beverage Containers?

Author: Roe Li

Safety is of the utmost importance when making food and beverage containers. Glass is a popular material for making food and beverage containers due to its non-porous, hygienic, and easy-to-clean qualities. While some clear glass bottles are safe to use for storing food and beverages, other types of glass may contain harmful chemicals that could leach into the food or beverage. There needs to be more clarity regarding what kinds of glass are food-safe. This blog post will explore the answer to is all glass food safe. We’ll also discuss the various types of food-grade glass available and the pros and cons of each.

I. What Is Glass Made From?

Glass is a brittle, transparent material that is made from a mixture of silica (sand), soda (sodium carbonate), and lime (calcium oxide). When these ingredients are heated to extremely high temperatures, they form a liquid that can be molded into various shapes. Once the glass cools and hardens, it retains its shape.

Glass is used in a variety of applications, from windows to drinking glasses and glass jars to light bulbs. It is also used in some industrial applications, such as in the production of fiberglass.

While glass is made from a variety of natural ingredients, the exact recipe depends on the type of glass being produced. For example, some types of glass contain lead, which is added to give the glass a higher melting point. Lead-free glass is also available, but it is more expensive.


1. Glass Production With Sand

Glass production involves four main steps: sand preparation, batching and mixing, furnace operations, and forming and finishing.


1) Sand Preparation: The first step in the glass production process is gathering the appropriate sand amount. The type of sand used can vary depending on the type of glass being made, but it is generally taken from a sandy beach or deposit. Once the sand is gathered, it is then cleaned and sifted to remove any impurities.


2) Batching and Mixing: The next step is to batch and mix the sand with other ingredients like soda ash, limestone, and cullet (recycled glass). The exact proportions of these ingredients will vary depending on the type of glass being made. Once all of the ingredients are combined, they are fed into the furnace.


3) Furnace Operations: The furnace is where the actual glass is formed. The furnace is heated to an extremely high temperature (around 2,700 degrees Fahrenheit) and the batch is melted down. Once the batch is melted, it is formed into what is called a “gob”.


4) Forming and Finishing: The gob is then cooled and cut into manageable pieces called “blanks”. These blanks are then placed onto a metal table called a “glory hole”. From the glory hole, the blanks are taken to a “greenhouse” where they are annealed (cooled gradually to relieve stress). The final step is to cut and finish the glass into the desired shape and then put it into a mold to make glass bottles and other glass products.


2. Other Materials That Are Used In Making Of Glass

The manufacturing of glass and glass products uses a variety of other materials. Some of these are used in the batch process, while others are used in the formation of the glass. 

Batch materials include cullet (recycled glass), soda ash, limestone, dolomite, and feldspar. These ingredients are combined and heated to create the glass. 


1) Soda Ash

Soda ash, also known as sodium carbonate, is an important industrial chemical. It is used in a wide variety of manufacturing processes, including the production of glass. Soda ash is the primary ingredient used in making flat glass for windows, beer bottles, doors, and other applications.

Soda Ash is a key ingredient in making glass. Soda ash is used in two main ways in the glassmaking process: batch-melting and continuous-fiber melting. In batch melting, soda ash is added to sand, cullet (crushed recycled glass), and other ingredients in a furnace. The furnace is then heated to a high temperature, typically 2,700 degrees Fahrenheit, and the materials are melted together. The molten glass is then formed into desired shapes and cooled.

In continuous-fiber melting, soda ash is used to make a glass fiber that is used in the reinforcement. A furnace heats the ingredients to a high temperature, typically 2,800 degrees Fahrenheit. The molten glass is then drawn out into thin fibers that are cooled and used as reinforcement in composite materials.


2) Limestone

Limestone rock is used in glassmaking because it contains calcium oxide, which is a flux that helps to reduce the viscosity of the glass melt. Limestone also acts as a stabilizer, preventing the glass from becoming too fluid and increasing its resistance to thermal shock. Adding limestone to the glass batch also helps to increase the clarity of the glass.


3) Cullet

Cullet is a key ingredient in the production of glass. It is made up of recycled glass that has been crushed into small pieces. By weight, the cullet typically makes up 20-25% of the batch mixture used to create new glass. 

The use of a cullet reduces the number of raw materials needed to make glass. It also saves energy and reduces greenhouse gas emissions during the glass-making process. Cullet can be used to make all types of glass, including clear, amber, and green.

II. What Is Food-Grade Glass?

Packaging materials, like glass and plastic containers, come into indirect contact with food as part of the production process. In the United States, the Food and Drug Administration (FDA) is responsible for overseeing food safety regulations and determining which materials are considered food-safe, including the processes used in glass bottle manufacturing and the creation of food-safe glass bottles and jars. Food packaging options, including plastic and glass containers, must be validated by the FDA for food safety as part of its qualification process.

Food-safe glass is a type of glass that is safe to use for food and beverage products. This type of glass is made with specific manufacturing processes and materials that make it safe for use with food items. Food-grade glass is often used in food packaging, such as bottles and jars, as well as in cookware and food storage containers.

Soda-lime glass bottles and jars are not “food additives,” according to the FDA. However, soda-lime glass is classified as Type I, II, or III- all food safe, or GRAS (generally considered safe). Therefore, soda-lime bottles are often chosen as the packaging for food and beverage products.

Type I Borosilicate Glass

Type I borosilicate glass is a type of glass that is often used in food and beverage applications. This type of glass is made from sand, soda ash, and Boron oxide, and it is distinguished from other types of glass by its low coefficient of thermal expansion. This property makes borosilicate glass resistant to thermal shock and less likely to break when exposed to sudden temperature changes.

In addition to its thermal resistance, borosilicate glass is also non-porous and does not absorb flavors or odors. This makes it a popular choice for food and milk bottles, as it will not retain any flavors from previous contents. Additionally, borosilicate glass is dishwasher safe, making it easy to clean and sanitize.

Type II Treated Soda Lime Glass

Type II treated soda lime glass is a food-safe glass that has been treated to resist staining and leaching. This type of glass is often used in food packaging, such as jars and bottles, and in food service applications, such as plates and bowls. Type II treated soda lime glass is also commonly used in lab applications.

Type III Soda Lime Glass

Type III soda-lime lass is a food-safe glass often used in packaging and glass smoking bottles & pipes. It is made of soda ash, limestone, and sand, which are melted together and then cooled to create the final product. This type of glass is precise, durable, and highly resistant to heat and chemicals. It is also non-porous, which means it will not absorb colors or flavors from food.

Type III soda lime glass is safe for most food-related uses but is not recommended for highly acidic foods or beverages. It is also not recommended for hot foods or drinks, as it can break or shatter.

III. Does Glass Have BPA?

Most people know that glass is a safe, healthy choice for storing food and beverages. But what about the chemicals that can leach into food from glass containers? Or does glass have BPA? One of the most common chemicals in glass is bisphenol A (BPA).

BPA is a synthetic compound used to make certain plastics and resins. It’s been linked to various health concerns, including reproductive problems, cancer, and obesity. However, the vast majority of research on BPA has been done on animals, so it’s unclear if the same effects occur in humans.

Glass is a safe alternative to plastic because it doesn’t contain BPA. However, some glass containers may be coated with BPA-containing resins to make them more durable. If you’re concerned about BPA, look for glass containers labeled “BPA-free.”

VI. How Do We Know If A Glass Bottle / Jar Is Food-Grade

When it comes to food-safe glass jars, they must meet specific standards to be approved by the FDA and other regulatory agencies. Generally, food-safe glass should be free of lead, cadmium, arsenic, and other toxic materials. It should also be free of chemical treatments such as coatings, glazes, or laminates containing unsafe ingredients.

It’s essential to use food-safe glass bottles when canning or storing food. But how can you tell if a glass bottle or jar is food-grade?

The first thing to understand is that there are different types of glass, and not all are considered food-grade. Three main types of glass are commonly used in food storage:

  • Soda-lime Glass: This is the most common type of glass and is usually what you think of when you think of glass containers. It’s made with sodium carbonate and lime and is typically used for soda bottles, food jars, and cooking oil bottles.
  • Tempered Glass: This type of glass is stronger and more resistant to breakage than soda-lime glass. It’s often used for oven doors, microwave doors, and food storage containers that need extra durability.
  • Borosilicate glass: This is a type of glass that is made with borosilicate minerals, which makes it more heat-resistant than other types of glass. It’s often used for things like laboratory glassware and cookware.

You can also check the glass bottle manufacturer’s website to see if the container is listed as food-grade. Many manufacturers will explicitly state whether or not their containers are safe for food storage.

The second way to tell if a glass container is food-grade is to look for a label that says “USDA Approved.” This means that the container has been tested and approved by the United States Department of Agriculture for food storage.

If you’re still unsure, you can contact the glass container manufacturer and ask if it is safe for food storage. In general, it’s best to err on the side of caution and use only food-grade containers for canning and storing food. Once you have determined that a container is food-grade, you can be sure it is safe to use for canning and bottling food.


V. Bottomline

The answer to whether or not all glass is food-safe for making food and beverage containers is yes. However, it is essential to ensure that the particular glass being used meets specific standards, such as those set by the FDA, for safety and purity. When buying glass containers, make sure to choose ones that are labeled as safe for food and beverages.

This will ensure that they have been tested and meet the standards set by the FDA. Additionally, take the necessary steps to properly care for your glass containers to stay safe and sanitary for years to come. By following these guidelines, you can be sure that any glass container you choose will be safe and secure for your food and drinks. To purchase high-quality food-safe containers and jars, contact us. We offer world-class products at very affordable rates.

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