What‘s the Difference Between Borosilicate Glass and Tempered Glass Water Bottles?

Are you planning to launch a new glass water bottle, but are unsure which material to choose? Borosilicate glass and tempered glass are the two most common types of glass. This article will discuss the differences between these two types of glass water bottles from 4 aspects. You will know which one to choose after reading.

Composition of Borosilicate Glass and Tempered Glass

Borosilicate Glass

Borosilicate glass is a special type of glass containing boron trioxide. Its main ingredients are silicon dioxide and borax. The boron content of ordinary borosilicate glass usually ranges from 12% to 15%. This composition formula effectively reduces the thermal expansion coefficient of the glass. This means that, unlike ordinary glass, borosilicate glass water bottles do not break when subjected to extreme temperature changes.

Tempered Glass

Tempered glass is not an independent type of glass. Instead, it is a type of safety glass made from ordinary soda lime glass through a special heat treatment process.

The chemical composition of tempered glass has not changed. The alteration is due to the physical processing rather than any change in the formula. The typical composition of soda lime glass consists of silica (about 70%), soda ash (about 15%), limestone (about 9%), and a small amount of other additives.

Properties of Borosilicate vs Tempered Glass Water Bottles

Thermal Shock Resistance

Borosilicate glass can withstand greater temperature fluctuations. If your water bottle product requires frequent temperature changes between hot and cold, it is recommended that you choose borosilicate glass.

Impact Resistant

Borosilicate Glass Water Bottles

Borosilicate glass has relatively poor impact resistance. When borosilicate glass is dropped, it breaks in a similar way to ordinary glass, and more sharp fragments are likely to be produced.

However, there are ways to improve it. The winning work of the Red Dot Design Award, “X Bottle”, protects the bottle body by coating the liquid silicone outer layer, ensuring that the water bottle remains intact rather than breaking when dropped. Or you can also pair your product with a fabric cup cover.

Tempered Glass Water Bottles

The impact resistance of tempered glass is significantly better, with its strength being 2.5 to 4 times that of ordinary glass. Moreover, the bending strength of tempered glass is 3 to 5 times that of ordinary glass. The excellent impact resistance gives tempered glass a significant advantage in applications where water cups may fall.

Breakage and Safety

The fragmentation pattern of borosilicate glass is similar to that of ordinary soda-lime glass. Once it breaks, it will form sharp fragments. The key safety feature of tempered glass lies in the fact that once it breaks, it will shatter into small, blunt-edged particles, significantly reducing the risk of injury to humans.

Transparency

Borosilicate glass has higher transparency and a smoother surface. The high transparency enhances the aesthetic value of the product, allowing the colour of the internal liquid to be presented more clearly. So it is suitable for products that highlight the appearance of liquid.

The transparency of tempered glass is slightly lower than that of borosilicate glass. If the brand requires the utmost transparency to show the colour of the drinks, tempered glass is not the best choice.

Wall Thickness

Due to the good hardness and high-temperature ductility of borosilicate glass, the bottle body can be made thinner and lighter during glass blowing or pressing. Compared to water cups of the same capacity, borosilicate glass products are 15% to 30% lighter than soda-lime glass products.

Tempered glass usually has a thicker wall and a more substantial appearance. It may not be suitable for brands that aim for visually high-end and lightweight products.

Chemical Stability and Corrosion Resistance

Borosilicate Glass Water Bottles

Borosilicate glass has very high chemical stability. It does not react chemically with acidic or alkaline substances and does not leach harmful chemicals into beverages. In ISO tests, borosilicate glass has an acid resistance rating of 1 (the highest) and an alkali resistance rating of 2. It can be used to store fruit juices, carbonated beverages, acidic liquids, and is even suitable for packaging medicines such as ampoule bottles.

Tempered Glass Water Bottles

The base material of tempered glass is sodium calcium glass, and its chemical resistance is slightly weaker than that of borosilicate glass. If it is necessary to have long-term contact with strong acidic beverages, the material composition of the tempered glass water cup should be confirmed to comply with the FDA/LFGB testing standards.

Applications of Borosilicate Glass and Tempered Glass Water Bottles

Still do not know how to choose between borosilicate and tempered glass water bottles? Here is a summary of applications.

Borosilicate Glass Water Bottles

Tempered Glass Water Bottles

Cost of Borosilicate Glass and Tempered Glass Water Bottles

Borosilicate Glass Water Bottles

Borosilicate glass has a higher cost, being 30% to 50% more expensive than ordinary glass. The production of borosilicate glass water bottles requires high-temperature melting, which incurs higher energy consumption and costs.

Although borosilicate glass cups have higher raw material and energy consumption costs, they have a stronger premium pricing power. Moreover, when the freight is calculated based on weight, the lighter weight of borosilicate glass cups can help you save some freight.

Tempered Glass Water Bottles

The raw material for tempered glass (sodium calcium glass) is relatively inexpensive. However, the production of tempered glass incurs high costs due to the depreciation of the expensive tempering furnaces. Moreover, it cannot be further processed after tempering, which leads to high initial processing pressure and an increase in the waste rate. Therefore, the final factory cost of tempered glass is not as low as you might think.

The cost advantage of tempered glass cups lies in their low return rate. In applications such as sports, where the cups are prone to breakage, the impact resistance of tempered glass cups can reduce the after-sales costs. Moreover, merchants can use fewer cushioning packaging materials to lower the overall freight.

FAQ

For the European and American Markets, What Are the Mandatory Requirements for Food Safety Certification of Glass Water Cups?

The common glass water cups imported to the United States are required to meet the FDA CFR Title 21 standards for materials. This ensures that the glass surfaces in contact with food do not leach harmful chemicals and do not contain heavy metals such as lead and cadmium.

For the EU market, the strictest standard is the LFGB. The LFGB regulations not only require the safety of raw materials, but also focus on a more comprehensive screening of contaminants, and require the provision of test reports.

Can Logos or Custom Brand Patterns be Printed on Borosilicate Glass and Tempered Glass Water Bottles?

Yes. Both materials support screen printing, heat transfer printing and spray coating. For borosilicate glass water bottles, the screen printing accuracy is the highest, the ink adhesion is excellent, and the surface of the borosilicate is very smooth, making it suitable for various font styles and colour designs.

The printing of tempered glass water bottles is slightly more challenging. There may be microscopic deformations on the surface of tempered glass. To ensure the adhesion of the ink and coating is long-lasting, the supplier must strictly control the pre-treatment of the glass before tempering and the printing process before coating.

What Packaging Is Recommended to Reduce Breakage During Ocean Freight for a Glass Water Bottle?

To reduce the damage during the transportation of glass water bottles, suppliers usually use separate cardboard partitions, foam pads or airbags inside the main box. Some factories also apply silicone sleeves on each glass water bottle to absorb impacts. For tempered glass, the inherent strength allows for slightly reduced cushioning.

How Do I Test the Heat Shock Resistance of a Glass Water Bottle Sample?

To verify the thermal shock performance of a glass water bottle, you can perform a simple test. Place the empty bottle in a freezer at 0°F (-18°C) for 2 hours, then immediately pour boiling water (212°F / 100°C) into it. A genuine borosilicate glass water bottle will survive this without cracking, while a tempered glass water bottle may crack if the temperature difference is over 257°F (125°C).

For professional verification, ask the supplier for a heat shock test certificate following standards like ISO 718 or ASTM C149.

Do Glass Water Bottles Affect the Taste of Water Compared to Plastic？

No, glass water bottles are chemically inert, which means they do not release any taste or odour into the water. Unlike plastic bottles, which may leach out BPA or stale flavours over time, glass water bottles preserve the pure, original taste of the drinks.

Final Thoughts

A successful business not only requires the right products but also a reliable partner. Kreat is an experienced water bottle manufacturer in China. No matter which material you choose, we can guarantee you a satisfactory quality of the water cups. We can also offer OEM services. Welcome to contact us!