When selecting capillary tubes for laboratory or industrial use, the choice between fused silica vs quartz capillary tubes vs borosilicate glass is critical. Each material offers distinct advantages in UV transmission, temperature resistance, chemical inertness, and cost. This guide compares all three so you can choose the right fused silica or quartz capillary tube for your application.
Why the Choice of Fused Silica vs Quartz Capillary Tubes Matters
Selecting the wrong capillary tube material can compromise your analytical results or cause premature component failure. Fused silica vs quartz capillary tubes is one of the most common decisions faced by lab managers, instrument engineers, and procurement teams. While both materials share high SiO₂ content, their purity levels, UV cutoff wavelengths, and thermal properties differ in ways that are critical for precision applications. Borosilicate glass, though cost-effective, cannot match the performance of fused silica or quartz capillary tubes in demanding environments. For a reference on optical glass properties, see the fused quartz overview on Wikipedia.
Material Selection Guide
Fused Silica vs Natural Quartz
vs Borosilicate Glass Capillary Tubes:
Complete Lab Selection Guide
Choosing the wrong capillary tube material wastes budget and compromises experimental results. This guide gives you the data — UV transmission, temperature limits, chemical resistance, and cost — so you can make the right call the first time.
Why material choice matters more than you think: A researcher using natural quartz capillaries in a 185 nm UV spectroscopy application may see up to 40% signal loss compared to UV-grade fused silica — without any obvious indication that the material, not the instrument, is the problem. This guide prevents that mistake.
Section 01
Understanding the Three Materials
All three are silicon-dioxide–based, but their manufacturing processes, purity levels, and resulting properties differ significantly. Here’s the 30-second version:
Premium
Synthetic Fused Silica
Manufactured from ultra-pure chemical precursors via flame hydrolysis or CVD. Virtually free of metallic impurities. The gold standard for optical and analytical applications.
≥99.99%SiO₂ purity
Standard
Natural Fused Quartz
Produced by melting naturally occurring crystalline quartz. Contains trace levels of Al, Ti, and other impurities from the natural source. Well-suited for many UV and high-temperature uses.
≥99.9%SiO₂ purity
Economy
Borosilicate Glass
~80% SiO₂ with B₂O₃ and Na₂O additives. Far easier and cheaper to manufacture. Good general-purpose lab glass — but limited in UV, temperature, and chemical resistance.
~80%SiO₂ content
Section 02
Full Specification Comparison
Side-by-side across the seven properties that matter most for laboratory and industrial capillary tube selection.
| Property | Synthetic Fused Silica | Natural Fused Quartz | Borosilicate Glass |
|---|---|---|---|
| SiO₂ Purity | ≥99.99% Best | ≥99.9% | ~80% Lowest |
| UV Transmission (start) | ~160–185 nm Best | ~240–250 nm | >310 nm Limited |
| Spectral Range | 160 nm – 3,500 nm Widest | 240 nm – 3,000 nm | 310 nm – 2,500 nm Narrowest |
| Max Continuous Temp. | 1,100°C Best | 1,100°C Best | ~450–500°C Limited |
| Thermal Expansion (CTE) | ~0.55 × 10⁻⁶/°C Lowest | ~0.55 × 10⁻⁶/°C Lowest | ~3.3 × 10⁻⁶/°C |
| Chemical Resistance | Excellent (highest of any glass) Best | Excellent | Good (attacked by strong alkalis & HF) Weaker |
| OH Content (IR use) | Low-OH grades available Flexible | Low (natural origin) | Variable, generally higher |
| Metallic Impurities | Essentially none Purest | Trace Al, Ti | Significant (B, Na, K, Al) Highest |
| Relative Cost | $$$ (Premium) | $$ (Mid-range) | $ (Lowest) Cheapest |
| Fabrication Precision | High (ID from 90 µm) Best | High | Moderate |
Section 03
UV Transmission: Where the Differences Are Critical
UV cutoff wavelength is often the single most important factor in analytical applications. Even a 30 nm difference can make or break an experiment.
Synthetic Fused Silica
Transmits from ~160 nm to 3,500 nm. UV-grade grades (e.g., Suprasil, JGS1) achieve >90% transmittance at 185 nm. The only choice for ArF excimer laser applications (193 nm), deep-UV spectroscopy, and VUV work. Metallic impurities are at parts-per-billion level — negligible effect on transmission.
Natural Fused Quartz
UV transmission starts at ~240–250 nm. Suitable for most UV-Vis spectroscopy (e.g., 254 nm germicidal, 280 nm protein analysis, 260 nm nucleic acids). Trace Al and Ti impurities limit deep-UV performance. An excellent mid-range choice when you don’t need sub-250 nm work.
Borosilicate Glass
Transmission begins only above 310 nm — meaning it blocks most of the UV spectrum entirely. B₂O₃ and Na₂O additives absorb UV strongly. Not suitable for any UV analytical technique. Acceptable for visible-wavelength applications and general fluid handling where UV performance is irrelevant.
Practical Impact
In HPLC UV detection at 210 nm, using natural quartz instead of fused silica can cause background absorption that masks low-concentration analyte peaks. In XRD sample holders, borosilicate scatter artifacts below 300 nm can corrupt diffraction data. Choose material based on your lowest required wavelength — not just the typical range.
Section 04
Temperature Performance & Thermal Shock Resistance
This is where borosilicate glass falls sharply behind — and where both fused silica grades deliver comparable, excellent performance.
Maximum Use Temperature
Both fused silica grades withstand continuous operation to 1,100°C and short-term peaks to 1,450°C. Borosilicate glass softens around 820°C and is typically rated for continuous use up to only 450–500°C. For any furnace tube, pyrolysis, or high-temperature reaction application, borosilicate is not an option.
Thermal Shock Resistance
Fused silica’s ultra-low CTE (0.55 × 10⁻⁶/°C) means rapid temperature changes — even going from 1,000°C into cold water — will not cause cracking. Borosilicate glass (CTE 3.3 × 10⁻⁶/°C) is better than ordinary glass, but still 6× higher than fused silica. For rapid thermal cycling, fused silica is the clear choice.
Rule of thumb: If your application involves temperatures above 500°C, rapid thermal cycling, or both — choose fused silica (either grade). Reserve borosilicate glass for ambient and moderate-temperature uses (up to ~250°C for routine lab work).
Section 05
Application-by-Application Recommendation
Different applications have different bottlenecks. Here’s the fastest-possible lookup for the most common use cases.
🔭
UV-Vis / UV Spectroscopy
Requires transmission from 190–350 nm. Background absorption from impurities directly corrupts absorbance readings.
✔ Synthetic Fused Silica🔗
Fiber Optic Connectors / Ferrules
Requires tight ID tolerance (±0.005 mm), smooth bore surface, and dimensional stability. UV grade preferred for broadband fiber.
✔ Synthetic Fused Silica⚗️
HPLC / Capillary Electrophoresis
Chemical inertness and UV transparency from 190 nm critical. Metal impurities in natural quartz can interfere with trace metal analyses.
✔ Synthetic Fused Silica🔬
X-Ray Diffraction (XRD) Capillaries
Thin-wall capillaries for powder diffraction sample holders. Low scatter background and chemical inertness required.
✔ Natural Quartz (cost-effective)🧬
Microfluidics / Lab-on-a-Chip
Biocompatibility, chemical inertness, and precise inner channels. UV imaging capability adds value in cell biology applications.
✔ Synthetic Fused Silica🌡️
High-Temperature Furnace Tubes
Continuous >500°C use, thermal cycling, or reactive gas environments. Borosilicate simply cannot survive these conditions.
✔ Natural Quartz (cost-effective)🧪
General Lab Fluid Handling (<250°C)
Non-UV, ambient or moderate temperature, non-aggressive chemistry. Cost efficiency is the dominant factor here.
✔ Borosilicate (budget choice)💊
Pharmaceutical / Biomedical
Zero contamination tolerance. Trace metals from natural quartz or borosilicate can interfere with bioassays or drug stability tests.
✔ Synthetic Fused SilicaSection 06
Quick Decision Framework
🎯 3 Questions to Pick the Right Material
Question 1
Does your application require UV light below 250 nm?
HPLC, deep-UV spectroscopy, excimer laser, photochemistry, fiber optic VUV.
→ Yes: Synthetic Fused Silica onlyQuestion 2
Does your application involve temperatures above 500°C?
Furnace tubes, pyrolysis reactors, semiconductor processing, thermal cycling tests.
→ Yes: Fused Quartz (either grade)Question 3
Is cost the primary constraint & UV/temp limits acceptable?
General fluid handling, visible-light or no-light use, <250°C, non-aggressive chemistry.
→ Yes: Borosilicate GlassSection 07
Cost vs. Performance: Making a Rational Trade-Off
The price difference is real — but so is the cost of using the wrong material. Here’s how to think about the trade-off.
When to pay for Fused Silica
If your capillary tube is part of an analytical instrument, optical assembly, or biomedical device — the tube cost is typically <1% of total system cost. Using inferior glass to save $20 per tube and risking $200K instrument data integrity is a false economy. Always match material to specification.
When borosilicate is genuinely fine
Fluid-handling applications at room temperature, visible-light flow cells above 320 nm, simple sample containers with no UV requirement, teaching labs, and prototype builds where final material selection hasn’t been confirmed. Borosilicate serves these roles well at 30–50% the cost of quartz.
Not Sure Which Material Is Right for Your Application?
Our technical team reviews your specifications and recommends the optimal material — at no charge. Custom OD/ID, non-circular cross-sections, and tight tolerances are our specialty.
sales@machinedquartz.com📌 Key Takeaways
- Synthetic fused silica is the premium choice for UV applications (below 250 nm), analytical instruments, fiber optics, biomedical, and any application requiring maximum purity. It carries the highest price but the lowest risk.
- Natural fused quartz delivers the same temperature and thermal shock resistance as synthetic silica, at a lower cost. It’s the ideal choice for high-temperature furnace work, XRD capillaries, and UV applications above 250 nm.
- Borosilicate glass is perfectly appropriate for general-purpose, ambient-temperature, non-UV laboratory applications. It’s not a compromise — it’s the right material for the right job, at the lowest cost.
- When in doubt, specify your minimum required wavelength and maximum operating temperature to your supplier — these two parameters alone determine the correct material 90% of the time.
- MachinedQuartz supplies all three material grades in 9+ cross-sectional shapes with OD from 0.5–8 mm and ID from 90 µm. Custom lengths and tolerances available with no minimum order quantity.