Is All Glass Food-Safe?

When it comes to food-safe bottles and food-safe jars, glass is a popular choice due to its safety and sustainability benefits. Glass doesn’t leach chemicals into its contents, and prevents external factors such as oxygen from affecting the product’s flavor and integrity. It is also 100% recyclable and can withstand the high temperatures required for sterilizing. 

However, not all glass containers are food-safe, or approved for direct contact with food. Depending on its components, glass may be more or less suitable for certain applications, such as food and pharmaceuticals. As a business owner searching for the ideal packaging, it’s important to understand the standards that food-safe glass must meet to uphold health and safety.

Glass is composed of natural raw materials which are melted and shaped into the products we love. Most common glass types contain silica sand as well as other ingredients that affect properties such as food-safety.

In the United States, food-grade or food-safe glass containers adhere to Food and Drug Administration (FDA) standards for their intended purposes. The FDA conducts safety assessments to determine whether a packaging material is safe for contact with food. These assessments test whether any substances within the material migrate to the food and if the migration is toxicologically safe. 

Is all glass food-safe? Different glass types contain various compounds and coatings, so the FDA cannot approve all glass as food-grade. However, there are three glass types which are commonly regarded as food-safe.

Due to similarities between the standards for food and pharmaceutical packaging, the three glass types generally recognized as food-safe are also recognized by the United States Pharmacopeia (USP) as safe for medicine use. The USP refers to these three types of glass as Type I, Type II, and Type III.

Type I glass is a strong borosilicate glass, made with silica, boron oxide, and small amounts of sodium oxide and aluminum oxide. Also known as “neutral glass”, borosilicate glass boasts superior durability, heat resistance, and chemical resistance to strong acids and alkalis. 

In 1913, the brand Pyrex popularized borosilicate glass for cookware. Borosilicate glass proved to be very resistant to breaking from thermal shock. Its ability to withstand temperature changes made it great for vials, baby bottles, baking dishes, measuring cups, and other kitchenware.

Type I glass also has a high melting point. While this is excellent for applications that involve high heat, it means the glass requires a special manufacturing process. This makes it the most expensive of the three.

Type II glass is sulfur-treated soda lime glass. Also called “de-alkalized glass”, this glass’s sulfur dioxide surface treatment neutralizes alkaline oxides, improving water, chemical, staining, and leaching resistance. It is frequently dyed, leading to better UV protection for its contents.

Type II glass is often seen as a more affordable replacement for Type I glass or as a modified version of Type III glass. Although less common than the other glass types, treated soda lime glass is often used for glass pill bottles and vials.

Type III glass is a versatile soda lime glass, made with silica (silicon dioxide), soda (sodium oxide), and lime (calcium oxide). This glass type is relatively affordable and the most commonly available, making up a large majority of glass worldwide. It is used for food-safe jars, food-safe bottles, food storage containers, mixing and serving bowls, cups, and most other food and beverage containers.

Type III glass is not as fortified as Type II, or as resistant to thermal shock or corrosive chemicals as Type I, but its qualities suffice for most packaging needs. It is durable, non-porous, and boasts average heat and chemical resistance. Soda lime glass is also inexpensive to manufacture and easy to recycle due to its low melting point.

In the packaging industry, manufacturers who produce glass for food applications are responsible for making sure their glass containers are free of harmful substances and meet FDA standards. Contacting the manufacturer directly is a great way to determine what type of glass a container is made of, and what applications it is intended for.

It is difficult to know for certain whether glass is food-safe based on appearance alone, since the answer lies in its chemistry. Food-safe glass should be free of lead, cadmium, arsenic, toxic coatings and glazing, or any other unsafe ingredients. However, these guidelines slightly vary depending on the length of food contact, as is the case with lead crystal glass.

Lead crystal glass has historically been used for decorative glassware, such as drinking glasses, decanters, or serving bowls. However, it contains lead, so it cannot be recognized as food-safe. Also known as lead glass or flint glass, this glass type was first created with a flint base. Shortly after, its formula was strengthened with lead oxide. It is important to note that “flint glass” has since become a popular misnomer for all clear-colored glass.

Due to the heirloom and antique value of lead crystal glass, there are strict guidelines available for those who choose to keep lead crystalware in use. When unchipped, well-preserved crystalware is used in short intervals, the exposure generally does not exceed our usual daily intake of lead. An example of a short interval would be the duration of a meal.

Canada’s health services suggest only using lead glass crystal for serving food and drinks, but never for long-term storage. They also acknowledge that more lead may be transferred when lead glass is used with highly acidic foods.

Glass experts suggest thoroughly washing lead crystal prior to initial use, and allowing the items to sit overnight in vinegar and water. Children or pregnant and breastfeeding women should not use lead crystal glassware at all.

At The Cary Company, we prioritize providing you with comprehensive knowledge about your products. In addition to exploring questions like, “Is All Glass Food-Safe?”, we create product descriptions that identify the intended applications of every container. Browse our versatile selection of glass containers or explore industry-specific categories!

Have any questions? Interested in finding a container? Contact one of our product specialists available to answer any questions and recommend products for you. Give us a call at 630-629-6600 or email us at sales@thecarycompany.com.