The material of laboratory glassware directly affects its temperature resistance, corrosion resistance, and thermal stability. The three main types currently on the market are borosilicate glass, soda-lime glass, and quartz glass (fused quartz). This article details their differences, performance parameters, and selection advice.
💡 Quick Conclusion
For laboratory glassware, borosilicate glass (3.3 borosilicate) is the first choice. It has low thermal expansion, excellent temperature and chemical resistance, and the best cost-performance ratio. Soda-lime glass is only suitable for simple experiments with low temperature requirements. Quartz glass is suitable for high-temperature or UV-transparent experiments, but is expensive.
1. Borosilicate Glass
🧦 Borosilicate Glass (3.3 Borosilicate)
✅ Recommended for Laboratories
1.1 Basic Composition
Borosilicate glass contains 12%~13% boron oxide (B&sub2;O&sub3;) and about 80%~81% silicon dioxide (SiO&sub2;). Due to the high boron content, the thermal expansion coefficient is extremely low, hence the name "3.3 borosilicate glass" (referring openly to a thermal expansion coefficient of 3.3 × 10&supminus;&sup6;/K).
1.2 Core Properties
- Low thermal expansion: α = 3.3 × 10&supminus;&sup6;/K, 1/3 of ordinary glass. Excellent thermal shock resistance.
- Wide temperature range: Can be used long-term at -50°C ~ 200°C, and short-term at up to 450°C.
- Resistant to acid and alkali corrosion: Except for hydrofluoric acid (HF) and hot phosphoric acid, it has good resistance to most acids and alkalis.
- High mechanical strength: About 2× stronger than soda-lime glass. Better bending and impact resistance.
- Good light transmission: Visible light transmittance > 90%. UV transmittance is better than soda-lime glass.
1.3 Common Brands & Standards
- SCHOTT Duran® (Germany): Inventor of borosilicate glass, the intenrational standard.
- Chinese PYREX: Equivalent to Duran, representative of domestic borosilicate glass.
- ISO 3585: Intenrational standard for borosilicate glass, specifying chemical composition and physical properties.
1.4 Suitable Scenarios
- ✅ Heating experiments (reflux, distillation, boiling)
- ✅ Experiments with frequent temperature changes (e.g., after high-temperature sterilization and cooling)
- ✅ Acid-base titration, chemical analysis
- ✅ Precision glass instruments (volumetric flasks, pipettes, burettes)
2. Soda-lime Glass (Ordinary Glass)
🧴 Soda-lime Glass (Ordinary Glass)
⚠️ Only for Simple Experiments
2.1 Basic Composition
Soda-lime glass contains 13%~15% sodium oxide (Na&sub2;O), 6%~12% calcium oxide (CaO), and about 70%~72% silicon dioxide (SiO&sub2;). This is the most common type of glass, used for making windows, bottles, cups, and other daily necessities.
2.2 Core Properties
- High thermal expansion: α = 9.0 × 10&supminus;&sup6;/K, about 3× that of borosilicate. Very prone to breaking due to sudden temperature changes.
- Narrow temperature range: Recommended long-term use temperature < 100°C. Must not be directly heated.
- Poor acid and alkali resistance: Easily corroded by alkaline solutions, and also not very resistant to most acids (except a few organic acids).
- Low mechanical strength: Brittle, poor impact resistance.
- Low cost: Abundant raw materials, simple production process. Cost is 1/3 ~ 1/2 of borosilicate glass.
2.3 Suitable Scenarios
- ✅ Simple experiments with low temperature requirements (e.g., room-temperature liquid mixing)
- ✅ Temporary simple setups
- ✅ Non-precision glass vessels (e.g., wash bottles, funnels)
- ❌ Must not be used for heating, acid/alkali experiments, or precision measuring instruments
3. Quartz Glass (Fused Quartz)
🗭 Quartz Glass (Fused Quartz)
💎 For High-end Special Experiments
3.1 Basic Composition
Quartz glass contains > 99.9% silicon dioxide (SiO&sub2;), almost pure silica. It is divided into fused quartz and synthetic fused silica.
3.2 Core Properties
- Extremely high temperature resistance: Can be used long-term at 1050°C ~ 1200°C, and short-term at up to 1600°C.
- Extremely low thermal expansion: α = 0.5 × 10&supminus;&sup6;/K, 1/6 of borosilicate. Excellent thermal shock resistance.
- Good UV light transmission: UV region (200nm ~ 400nm) transmittance is much higher than borosilicate glass. Suitable for UV analysis.
- Resistant to acid and alkali corrosion: Except for hydrofluoric acid and hot phosphoric acid, corrosion resistance is better than borosilicate glass.
- Expensive: Cost is 10 ~ 20 × that of borosilicate glass.
3.3 Suitable Scenarios
- ✅ High-temperature experiments (e.g., high-temperature melting, high-temperature reactions)
- ✅ UV spectroscopy analysis (requires high UV transmittance)
- ✅ Semiconductor processes (high purity requirements)
- ✅ Special experiments requiring excellent thermal shock resistance
4. Properties Comparison of Three Glass Materials
| Property | Borosilicate Glass | Soda-lime Glass | Quartz Glass |
|---|---|---|---|
| Thermal expansion (×10&supminus;&sup6;/K) | 3.3 | 9.0 | 0.5 |
| Long-term use temp (°C) | -50 ~ 200 | < 100 | 1050 ~ 1200 |
| Short-term temp resistance (°C) | 450 | 150 | 1600 |
| Thermal shock resistance | ✅ Excellent (ΔT > 200°C) | ❌ Poor (ΔT > 40°C causes breakage) | ✅ Superior (ΔT > 1000°C) |
| Acid/alkali resistance | ✅ Good (except HF & hot H&sub3;PO&sub4;) | ❌ Poor | ✅ Excellent |
| UV transmittance | Good (> 90%) | Poor | ✅ Excellent (> 95%) |
| Mechanical strength | ✅ High | Low | Relatively high |
| Relative price | 1× (baseline) | 0.3× ~ 0.5× | 10× ~ 20× |
| Recommendation for labs | ✅✅✅ Strongly recommended | ⚠️ Simple experiments only | ✅ Special high-temp/UV experiments |
5. How to Choose the Right Glass Material?
According to experimental needs, prioritize in the following order:
Priority 1: Does it need heating?
- Needs heating → Must choose borosilicate glass or quartz glass. Soda-lime glass must not be heated, it will break.
- Does not need heating → Continue to consider other factors.
Priority 2: Does it involve acids/alkalis?
- Involves acids/alkalis → Must choose borosilicate glass or quartz glass. Soda-lime glass is easily corroded.
- Does not involve acids/alkalis → Continue to consider other factors.
Priority 3: Are there high-temperature (> 450°C) or UV requirements?
- Has high-temp/UV requirements → Choose quartz glass.
- No special requirements → Choose borosilicate glass (best cost-performance).
📜 KODEX Product Material Note
All KODEX precision glassware (volumetric flasks, pipettes, burettes, flasks, beakers, etc.) are made of borosilicate glass (3.3 borosilicate), ensuring thermal stability, corrosion resistance, and precision in compliance with intenrational standards (ISO 3585). For custom quartz glass, please contact our technical team.
6. Frequently Asked Questions (FAQ)
❓ Can borosilicate glass be heated directly on an open flame?
Yes. Borosilicate glass can be directly heated on alcohol lamps, gas burners, or electric furnaces, but note:
1. Must not heat/cool abruptly: Preheat before heating (use small flame and heat slowly), and do not immediately put into cold water after heating.
2. Use an asbestos pad: For glass instruments with larger bottom areas (e.g., flasks), it is recommended to use an asbestos pad or heating mantle for more uniform heating.
3. Must not dry-heat: Glass instruments can only be heated when there is liquid inside. Dry heating will cause local overheating and breakage.
1. Must not heat/cool abruptly: Preheat before heating (use small flame and heat slowly), and do not immediately put into cold water after heating.
2. Use an asbestos pad: For glass instruments with larger bottom areas (e.g., flasks), it is recommended to use an asbestos pad or heating mantle for more uniform heating.
3. Must not dry-heat: Glass instruments can only be heated when there is liquid inside. Dry heating will cause local overheating and breakage.
❓ How to quickly distinguish borosilicate from soda-lime glass?
Several simple methods:
1. Check the marking: Borosilicate glass instruments usually have "Borosilicate" or "3.3" marked on them.
2. Thermal shock test (use with caution): Heat the glass instrument to 100°C, then quickly put into 20°C water. Borosilicate will not break; soda-lime glass will break.
3. Observe thickness: Borosilicate instruments are usually thinner and lighter because higher strength allows thinner walls; soda-lime instruments are thicker.
4. Ask the manufacturer: The most reliable method is to ask the manufacturer or check the product manual.
1. Check the marking: Borosilicate glass instruments usually have "Borosilicate" or "3.3" marked on them.
2. Thermal shock test (use with caution): Heat the glass instrument to 100°C, then quickly put into 20°C water. Borosilicate will not break; soda-lime glass will break.
3. Observe thickness: Borosilicate instruments are usually thinner and lighter because higher strength allows thinner walls; soda-lime instruments are thicker.
4. Ask the manufacturer: The most reliable method is to ask the manufacturer or check the product manual.
❓ Will borosilicate glass be corroded by hydrofluoric acid?
Yes. Hydrofluoric acid (HF) is the only acid that significantly corrodes glass, including borosilicate glass. Therefore, experiments involving HF should use plastic containers (e.g., PTFE, polyethylene), not glass instruments. HF generates gaseous SiF&sub4;, which is harmful to the human body. Operations must be conducted in a fume hood.
❓ What is the service life of glassware?
The service life of glassware depends on:
1. Frequency of use: Frequent heating and cooling will shorten lifespan.
2. Cleaning method: Using corrosive cleaning agents (e.g., chromic acid solution) will damage the glass surface and reduce mechanical strength.
3. Impact/scratches: Glassware is fragile; impacts will create micro-cracks and reduce strength.
Normally, borosilicate glass instruments can be used for 5~10 years under normal use. Replace promptly if cracks, scratches, or blurred scales appear.
1. Frequency of use: Frequent heating and cooling will shorten lifespan.
2. Cleaning method: Using corrosive cleaning agents (e.g., chromic acid solution) will damage the glass surface and reduce mechanical strength.
3. Impact/scratches: Glassware is fragile; impacts will create micro-cracks and reduce strength.
Normally, borosilicate glass instruments can be used for 5~10 years under normal use. Replace promptly if cracks, scratches, or blurred scales appear.
❓ Why are some glass instruments amber/brown colored?
Amber (brown) glass instruments have iron oxide, manganese oxide, and other coloring agents added to the glass raw materials, making the glass brown. Their function is to filter ultraviolet and visible light, preventing photosensitive substances (e.g., silver nitrate, iodides) from decomposing under light. The material of amber glass instruments is also usually borosilicate glass; performance is the same as transparent glass, only the color is different. For photosensitive experiments, amber glass instruments should be prioritized.