What Is Borosilicate Glass? Properties, Types and Laboratory Uses

If you work in an Australian laboratory, the glass you use affects every result you produce. Borosilicate glass is the standard material for scientific glassware worldwide, but understanding why it matters, when it is necessary, and how it compares to alternatives like soda-lime and quartz glass is essential for making informed purchasing decisions.

This guide covers the composition, properties, types, and practical applications of borosilicate glass, with specific guidance for Australian laboratories. For a broader overview of all laboratory glassware types, selection frameworks, and Australian compliance requirements, see our Complete Guide to Laboratory Glassware in Australia.

What Is Borosilicate Glass?

Borosilicate glass is a high-performance glass made primarily from silica (SiO₂) and boron trioxide (B₂O₃). This composition creates a tighter molecular network than standard glass, giving it exceptional resistance to heat, chemicals, and mechanical stress. It was first developed by German glassmaker Otto Schott in the late 19th century and has been the foundation of laboratory glassware ever since.

The most common laboratory grade is Borosilicate 3.3 (also known as Type 1, Class A under ASTM E-438). The "3.3" refers to its coefficient of thermal expansion: 3.3 x 10⁻⁶ K⁻¹. This is roughly one-third that of ordinary soda-lime glass, which is why borosilicate can move from a freezer to a hotplate without shattering.

Well-known brands include DWK Life Sciences DURAN®, Corning Pyrex® (laboratory grade), and BRAND® BLAUBRAND®. All are available through Cole-Parmer and VWR at John Morris Group.

Types of Borosilicate Glass

Not all borosilicate is the same. There are three primary grades, each with different compositions and thermal properties:

For Australian laboratories, Borosilicate 3.3 is the standard. It has the lowest thermal expansion, the highest softening point, and meets the strictest classification under ASTM, USP Type 1, and ISO 3585. The 4.9 and 5.4 grades are used in more specialised applications, including pharmaceutical packaging and light-sensitive storage.

Actinic (Amber) Borosilicate Glass: Protecting Light-Sensitive Samples

Australian laboratories working with photosensitive reagents, pharmaceutical compounds, or UV-degradable standards frequently require actinic (amber) borosilicate glass. According to DWK Life Sciences product specifications, amber DURAN glass provides less than 10% spectral transmission between 290 nm and 450 nm, effectively shielding contents from ultraviolet radiation and short-wavelength visible light that could cause photodegradation.

Modern actinic glass is created by diffusing amber stain into the outer surface of clear Borosilicate 3.3. This means the solution only contacts the chemically inert inner surface, maintaining the same thermal shock resistance and chemical durability as clear glass. Unlike opaque containers, amber borosilicate remains sufficiently transparent for lab personnel to observe liquid levels and sample condition during experiments.

Common actinic products include Class A volumetric flasks, pipettes, and storage bottles from DURAN and BLAUBRAND. If your lab handles light-sensitive solutions in pharmaceutical, biochemistry, or environmental testing workflows, actinic glass is the appropriate choice.

Borosilicate vs Soda-Lime vs Quartz: A Practical Comparison

The practical takeaway: Use borosilicate 3.3 for any application involving heat, aggressive chemicals, or autoclaving. Use soda-lime only for non-heated volumetric instruments, short-term storage, or teaching environments where breakage risk is acceptable. Use quartz only when you need deep-UV transmission or temperatures above 500°C. Many labs overspend by purchasing quartz for tasks where borosilicate would perform identically.

What Happens When You Use the Wrong Glass

Using soda-lime glass where borosilicate is required creates real problems in laboratories:

• Shattering during exothermic reactions: Mixing concentrated acids in soda-lime cylinders can generate enough heat to crack or break the bottom of the vessel. Borosilicate handles these thermal gradients safely.
• Cracking on hotplates: Soda-lime glass expands roughly three times more than borosilicate under heat. Placing soda-lime flasks on laboratory hotplates or magnetic stirrer hotplates commonly causes thermal shock cracking.
• Failure during autoclaving: Soda-lime does not reliably tolerate repeated high-temperature, high-pressure sterilisation cycles. Over time, micro-fractures develop and the glass fails without warning.
• Chemical contamination: Acidic substances gradually leach ions from soda-lime glass, causing microscopic corrosion and clouding. This contamination can compromise trace-level analyses where the chemical inertness of borosilicate is essential.

For more real-world examples of how glassware choices affect scientific outcomes in Australian labs, including case studies from the wine, environmental, and pharmaceutical industries, see our Complete Guide to Laboratory Glassware.

The Pyrex Warning: Not All Pyrex Is Borosilicate

One of the most common mistakes labs make when ordering borosilicate glassware for the first time is assuming all Pyrex is borosilicate. Corning distinguishes between PYREX (uppercase), their laboratory borosilicate 3.3 brand, and pyrex (lowercase), the consumer cookware brand now manufactured from tempered soda-lime glass in some markets including the United States. Laboratory-grade PYREX is always borosilicate 3.3, but consumer pyrex products may not offer the same thermal shock resistance and are not suitable for laboratory use.

When ordering for your lab, always verify that the product is specifically rated as Borosilicate 3.3, Type 1, Class A under ASTM E-438. Purchasing through an authorised laboratory supplier like John Morris Group ensures you receive genuine laboratory-grade borosilicate from verified manufacturers.

Common Mistakes When Ordering Borosilicate Glassware

After 70 years of supplying Australian laboratories, we see the same ordering errors repeatedly:

• Assuming all borosilicate is identical: Grades 3.3, 4.9, and 5.4 have different thermal limits and different ASTM classifications. Specifying the wrong grade can mean your glassware does not survive the thermal cycles your experiments require.
• Not specifying Class A vs Class B: Class A is precision-grade with the lowest error tolerances, required for analytical chemistry and pharmaceutical audits. Class B has double the permissible error and is only appropriate for education and non-regulated work.
• Overlooking traceability requirements: Labs operating under ISO 17025 (NATA accreditation) or GMP standards must order serialised, certified glassware with batch certificates. Standard items may not include the documentation needed for compliance audits.
• Using borosilicate where quartz is required: Borosilicate blocks most UV radiation below 300 nm and should not operate continuously above 500°C. For deep-UV spectrophotometry in UV cuvettes or extreme high-temperature work, quartz is necessary.

Australian Standards and Compliance

For Australian laboratories, borosilicate glassware must comply with several overlapping standards:

• ISO 3585: Defines the identification and classification of borosilicate glass appropriate for laboratory use.
• ASTM E-438: Classifies glass types. Borosilicate 3.3 is Type 1, Class A (the highest classification).
• USP Type 1 / European Pharmacopoeia Type 1: Required for pharmaceutical applications where glass contacts drug formulations.
• ISO 4787:2021: The current guideline for calibrating and using volumetric instruments (replaced AS 2162, withdrawn 2019; note that the earlier ISO 4787:2010 has also been superseded).
• AS/NZS 2243 Part 6: Covers safe handling of glassware under vacuum or pressure to prevent injury from breakage.
• ISO/IEC 17025: The basis for NATA accreditation, requiring traceable calibration of volumetric glassware.

John Morris Group provides NATA-accredited calibration services (Accreditation No. 4283) for pipettes and supports volumetric glassware verification through our factory-trained engineers across Sydney, Brisbane, Melbourne, Perth, and Auckland. Gilson PIPETMAN calibration is a particularly popular service for labs maintaining ISO 17025 compliance.

Cleaning and Maintaining Borosilicate Glassware

High-quality borosilicate glassware can last for many years or even hold its calibration indefinitely when properly cared for. In a poorly maintained lab, premature failure from cumulative surface damage, chemical etching, and thermal shock significantly shortens lifespan and increases replacement costs.

The key to longevity is proper cleaning. Rinse with distilled water after every use. For validated cleaning, use laboratory glassware washers with purified water from a MERCK Milli-Q system for the final rinse. Avoid abrasive cleaners that can scratch the glass surface and create nucleation points for future cracking. For our complete step-by-step cleaning protocol, see How to Clean Lab Glassware Properly.

Popular Borosilicate Glassware at John Morris Group

Our most popular borosilicate products reflect the breadth of applications across Australian laboratories:

• Pyrex 50 mL Volumetric Flask (Pack of 6) for routine analytical preparation and standard solution work.
• Pyrex 500 mL Kjeldahl Distilling Apparatus used extensively in food and feed protein analysis alongside Gerhardt digestion and distillation systems.
• DWK DURAN 250 mL Wide-Neck Laboratory Bottle for chemical storage, sample preparation, and media dispensing.
• Kimble Griffin 400 mL Beaker (KG-33 Glass, 12/case) a workhorse in university and research labs for daily mixing and heating.

Browse our full range of laboratory supplies and fixtures or contact our technical team on 1300 501 555 for guidance on glass type, volumetric class, and compliance requirements.

Frequently Asked Questions

What is borosilicate glass?
Borosilicate glass is a high-performance glass made from silica and boron trioxide. It has a very low thermal expansion coefficient (3.3 x 10⁻⁶ K⁻¹ for the standard laboratory grade), making it highly resistant to thermal shock, chemical corrosion, and mechanical stress. It is the global standard for laboratory glassware.

What is the difference between borosilicate and soda-lime glass?
Soda-lime glass has a thermal expansion rate roughly three times higher than borosilicate, making it prone to cracking under heat. Borosilicate is chemically inert and withstands autoclaving, while soda-lime can leach ions when exposed to acids. Borosilicate generally costs around 2 to 3 times more upfront but lasts significantly longer in laboratory environments.

What is actinic (amber) borosilicate glass used for?
Actinic borosilicate glass provides less than 10% spectral transmission between 290 nm and 450 nm, protecting light-sensitive reagents and pharmaceutical compounds from photodegradation. It is commonly used for volumetric flasks, pipettes, and storage bottles in pharmaceutical, biochemistry, and environmental testing labs.

Is all Pyrex made from borosilicate glass?
No. Laboratory-grade Pyrex by Corning is borosilicate 3.3. However, consumer Pyrex products sold in the US and other markets are often made from tempered soda-lime glass, which lacks the same thermal shock resistance. Always verify the product is rated as Borosilicate 3.3, Type 1, Class A under ASTM E-438 when purchasing for laboratory use.

Can borosilicate glass be used for UV spectrophotometry?
Borosilicate blocks most UV radiation below approximately 300 nm, so it is not suitable for deep-UV measurements. For UV spectrophotometry, quartz (fused silica) cuvettes are required. Borosilicate is fine for visible-light spectrophotometry and general colorimetric work.

Where can I buy borosilicate glassware in Australia?
John Morris Group supplies laboratory-grade borosilicate glassware from Cole-Parmer, DWK Life Sciences (DURAN, KIMBLE, WHEATON), BRAND (BLAUBRAND), Pyrex, and VWR. We also offer NATA-accredited pipette calibration and technical guidance on glass type selection. Call 1300 501 555 or browse our laboratory supplies.