Autoclaving Laboratory Glassware and Plasticware: Best Practices for Sterility and Safety

Sterilisation is one of the most critical processes in laboratories, ensuring that equipment and consumables are free from microorganisms before use. Autoclaving — the use of pressurised steam at high temperatures — remains the gold standard for sterilising laboratory glassware and plasticware. For Australian schools, universities, and industry labs, understanding what can and cannot be autoclaved is essential for both safety and compliance.

Autoclaving Glassware

BORO 3.3 borosilicate glass is ideal for autoclaving due to its low thermal expansion and resistance to heat shock. Beakers, flasks, reagent bottles, and Petri dishes made from BORO 3.3 can withstand repeated autoclaving cycles without cracking or degrading.

Best practices include:

• Avoiding sudden temperature changes (e.g., moving hot glass directly into cold water).
• Loosening caps and stoppers to prevent pressure build-up.
• Using gradual cooling cycles to reduce stress fractures.

LabChoice Australia’s BORO 3.3 glassware is ISO 3585 compliant, giving researchers confidence in both sterility and durability.

Autoclaving Plasticware

Not all plastics can be safely autoclaved. Polypropylene (PP) and polycarbonate (PC) are commonly used in laboratories because of their ability to tolerate autoclave conditions (121°C, 15 psi, 15–20 minutes).

Key guidelines include:

• Check the manufacturer’s specifications for autoclave suitability.
• Avoid repeated autoclaving of plastics like polystyrene (PS), which can warp or degrade.
• Separate plastics from glassware during cycles to prevent distortion.

LabChoice supplies polypropylene-based consumables such as bottles, cylinders, and pipette accessories that are certified safe for autoclaving.

Case Study: University Laboratory in Sydney

A microbiology teaching lab at a Sydney university replaced soda-lime beakers with BORO 3.3 sets from LabChoice Australia. Over two semesters, the lab reported zero breakages during autoclaving, compared to frequent losses previously. Switching to polypropylene centrifuge tubes also improved sterility assurance for student experiments, while reducing consumable costs.

Common Autoclaving Challenges and Solutions

• Residual moisture inside vessels → Dry glassware thoroughly before autoclaving.
• Deformed plastic lids or caps → Use autoclavable PP screw caps with venting features.
• Inconsistent sterilisation → Do not overload the autoclave chamber; allow proper steam circulation.

Comparison: Autoclaving Glassware vs Plasticware

Practical Applications in Australian Labs

• Education: Sterilising reusable glassware in school and university science labs
• Healthcare: Ensuring sterile diagnostic containers and culture vessels
• Research: Reliable sterilisation of microbial media and solution vessels
• Industry: Sterile QC workflows in food and pharmaceutical testing

FAQs

Q1. Can all glassware be autoclaved?
No. Only borosilicate glass such as BORO 3.3 should be autoclaved. Soda-lime glass is prone to cracking under heat stress.

Q2. How many times can plasticware be autoclaved?
Polypropylene items can typically withstand 10–50 cycles, depending on quality and design. Always inspect after each cycle.

Q3. What temperature and pressure are used in autoclaving?
Standard autoclaving is performed at 121°C, 15 psi, for 15–20 minutes.

Q4. Should caps and lids be closed during autoclaving?
No. Caps should be loosened or vented to allow steam penetration and prevent vessel rupture.

References

• ISO 3585: Borosilicate Glass 3.3 – Properties
• ASTM E2197 – Standard Quantitative Disk Carrier Test for Microbial Control Agents
• American Society for Microbiology (ASM) Laboratory Safety Guidelines
• University of Queensland Laboratory Safety Manual, 2023 Edition