Autoclaving Borosilicate Glassware: Safety, Standards, and Best Practices

Sterilisation is critical for laboratories across Australia, ensuring glassware and equipment are free from microorganisms. Borosilicate glassware (BORO 3.3) is the preferred choice because of its ability to withstand high temperatures and pressure during autoclaving. Following correct procedures not only guarantees sterility but also extends the lifespan of valuable laboratory glassware.

Why Borosilicate Glass is Autoclave-Safe

BORO 3.3 glass is manufactured to ISO 3585 standards, with a low coefficient of thermal expansion (3.3 × 10⁻⁶/K).

• Resistant to rapid heating and cooling cycles.
• Maintains structural integrity under pressurised steam (121–134 °C).
• Chemically stable, avoiding reactions during sterilisation.
• Suitable for repeated autoclave cycles without distortion.

This makes borosilicate glassware superior to soda lime or plastic alternatives in sterilisation-intensive laboratories.

Safety Considerations When Autoclaving Glassware

Even with durable glass, improper handling can lead to breakage.

• Inspect glassware for cracks or chips before use.
• Avoid sudden temperature changes — allow cooling before removal.
• Do not over-tighten stoppers or closures, as expansion may cause fractures.
• Use wire baskets or autoclave trays to prevent direct contact with chamber walls.

By following these steps, labs can reduce the risk of accidents and protect both staff and equipment.

Applications Across Australian Labs

• Educational labs: Sterilising reusable glassware for teaching.
• Microbiology labs: Preparing sterile flasks, beakers, and media bottles.
• Pharmaceutical and biotech labs: Ensuring compliance with GMP sterilisation protocols.
• Food and environmental labs: Eliminating contamination in testing glassware.

Comparison Table: Borosilicate vs Plastic in Autoclaving

FAQs

Q1: Can all borosilicate glassware be autoclaved?
Yes, but always confirm ISO 3585 compliance. Avoid using items with visible cracks or damage.

Q2: How often can glassware be autoclaved?
With proper handling, BORO 3.3 glassware withstands hundreds of autoclave cycles without loss of accuracy.

Q3: Should glassware be dry before autoclaving?
Yes, residual water can interfere with sterilisation and increase risk of cracking during heating.

Q4: Are screw-cap bottles safe to autoclave?
Yes, but caps should be loosened to prevent pressure buildup. PTFE or silicone liners are preferred.

References

• ISO 3585: Borosilicate Glass 3.3 — Properties and Standards.
• ASTM E140: Laboratory Glassware Thermal Resistance Tests.
• World Health Organization (WHO) Laboratory Biosafety Manual.
• University of Queensland Laboratory Safety Guidelines.
• NIST Chemistry WebBook, National Institute of Standards and Technology.