As a nylon tubing supplier, I get asked this question all the time—usually from engineers, product designers, and operations managers who are weighing material options for projects that need more than just fluid or gas flow. Let’s cut through the confusion here because when it comes to optical properties, “good” is relative. Nylon tubing isn’t a glass pipe, obviously, and it’s not as translucent as acrylic—but it has distinct optical advantages that make it a solid (sometimes even superior) pick for specific use cases. First, let’s ground this in real-world testing, because I don’t just sell nylon tubing; I’ve watched our products get tested in labs, and I’ve talked to dozens of clients about how their nylon tubing performs in their equipment. Nylon Tubing
To start with the basics: nylon (polyamide, for the chemists reading) is a semi-crystalline thermoplastic. That means it has both ordered, crystalline regions and amorphous, disordered regions inside its molecular structure. The ratio of these two parts is the first big factor in its optical properties. Most standard nylon tubing we supply is Type 6 or Type 6/6, the grades that are industry workhorses for pneumatic lines, fluid transfer, and general industrial use. Standard extruded nylon tubing from our facility is typically translucent, not fully transparent—you can see light pass through it, but you can’t get a crisp image through the wall. Compare that to clear PVC or acrylic tubing, which are fully amorphous, so they let light travel straight through with minimal scattering. That difference matters, but it’s not a flaw—it’s a feature for many applications.
Wait, let’s back that up with data. Last year, a client in the medical device industry tested our standard clear nylon tubing (we offer a clear grade specifically for optical visibility) against acrylic for a fluid level indicator. Their test used a 5mm inner diameter tube, 1m length, white LED light source on one end. The acrylic had a light transmittance of ~92% at 550nm (visible light), while our clear nylon came in at ~85%. That’s a 7% drop, but when they actually installed it on their assembly line, their operators could still easily see the fluid level—no eye strain, no misreads. The acrylic, on the other hand, got scratched during assembly, and the scratches scattered light so much that the level was impossible to see clearly after a week of use. That’s the trade-off: nylon’s surface is more abrasion-resistant, so even with a lower light transmittance, it held its optical clarity far longer than the softer acrylic. That’s a perfect example of why “good optical properties” depends on what you’re using the tubing for.
Another key optical property for tubing is haze. Haze is the amount of light that scatters when it passes through a material—high haze means it’s translucent, low haze means it’s clearer. Standard nylon tubing has a haze value of around 15-20%, while clear acrylic is around 2%. Again, that’s a difference, but for most pneumatic application visual indicators, that haze is an asset. Wait, let’s explain why: if you’re using tubing to show if air is flowing (like in a pneumatic control circuit), the slight scattering of light in nylon makes the air bubbles inside more visible. A client in agricultural equipment told us they switched from clear vinyl to our nylon tubing for their sprayer flow indicators because they could see tiny air bubbles that were invisible in the vinyl. The vinyl had a haze of only 5%, so the light passed straight through, and small bubbles just blended in. The nylon’s higher haze scattered the light, making each tiny bubble a bright, distinct spot against the white background of their equipment panel. That’s a win for nylon’s optical properties that I never would have anticipated until that client told us about their setup.
Now, let’s talk about the limitations because I’m not here to oversell. Nylon isn’t the best choice for applications requiring high optical clarity, like endoscopy equipment or liquid level sensors that need to transmit an image of what’s inside the tubing. For those uses, glass or clear polycarbonate is better, with transmittance levels over 90% and haze under 3%. But for most industrial, commercial, and even some consumer applications, nylon’s optical properties are more than sufficient—and they come with other benefits that make the trade-off worth it. Let’s list those benefits because they tie directly to why the optical properties matter in context: nylon is flexible, chemical-resistant, impact-resistant, and can withstand higher pressures than clear vinyl. If you need a tubing that can bend around tight corners without cracking, doesn’t degrade when exposed to hydraulic fluid or fertilizer, and lets you see flow or air bubbles, nylon’s optical properties balance perfectly with its physical properties.
I also want to address a common misconception about colored nylon tubing. A lot of suppliers will say “we sell colored nylon, so it has poor optical properties”—but that’s not entirely true. Colored nylon is made by adding pigment during extrusion, and the pigment’s particle size and distribution affect how much light is blocked. We supply custom colored nylon tubing for clients in food and beverage and automotive, and we can adjust the pigment load to keep light transmittance high when needed. For example, a craft beverage client used our amber-colored nylon tubing to transfer wine and cider—amber glass is standard for beverage lines to block UV light, which spoils the drink. Our amber nylon tubing had a transmittance of only 10% for UV light (350nm) while still having 70% transmittance for visible light, so they could see the flow of liquid through the tubing to spot clogs or air bubbles, just like with clear tubing. The alternative was amber glass tubing, which was fragile and had to be custom bent on-site—our nylon tubing was flexible, easy to install, and checked all their boxes for optical and material properties. That’s another example where nylon’s optical properties are tailored to a specific use case, which is why I get so many repeat orders from that client.
Another test we ran in our in-house lab last year: we extruded nylon tubing in three grades—Type 6 standard, Type 12 flexible, and a filled nylon for heavy-duty use. We measured light transmittance over 10,000 hours of continuous use, simulating exposure to oil, temperature fluctuations, and UV light. The standard Type 6 nylon had a transmittance drop of only 8%, going from 85% to 77%, while the clear acrylic we tested had a transmittance drop of 35% over the same period, due to yellowing and surface degradation from UV light. That’s a huge difference for long-term use. A client in the construction equipment industry uses our nylon tubing for hydraulic line leak detectors, and they reported that after 5 years of outdoor use, the tubing still lets them clearly see if fluid is leaking, whereas the acrylic they used previously turned yellow so badly after 2 years that they couldn’t see the leaks at all. The nylon doesn’t yellow nearly as much as other plastics, so its optical properties stay consistent over time, which is a critical long-term benefit.
Wait, let’s also mention light transmission for pressure sensing. Some clients use tubing to carry pressure-sensitive fluids, and they use optical sensors to detect changes in the fluid. For these applications, we’ve found that our nylon tubing’s light transmittance is perfectly matched to standard industrial optical sensors, which are calibrated for visible light. We had a client in HVAC testing use our nylon tubing for refrigerant pressure monitoring—their optical sensors worked with our tubing because the transmittance was high enough (around 80%) that the sensor could pick up the light signal, but the nylon’s slight haze eliminated glare from the equipment’s surrounding metal parts that had been interfering with their sensor’s accuracy when they used metal tubing with a coated interior. That’s a unique advantage I don’t hear suppliers talk about often: nylon’s optical properties can reduce glare, which is a big plus for optical sensing applications.
Now, let’s be honest about when nylon’s optical properties aren’t ideal. If you need to transmit an image through the tubing wall—like in a medical endoscope or a small camera line—nylon isn’t the right pick. For those uses, clear, low-haze plastics like polycarbonate or glass are necessary, and that’s not a gap we try to fill. But for 90% of the projects our clients bring us—pneumatic lines, fluid transfer, flow visualization, agricultural equipment, automotive fluid lines—nylon’s optical properties are more than adequate, and the material’s other strengths (flexibility, chemical resistance, impact resistance) make it the better choice over any other material.
I think the biggest takeaway here is that when evaluating “good optical properties,” you have to match the material to the application. Nylon isn’t clear, high-transmittance tubing, but it’s durable, long-lasting, and has optical properties that are tuned for real-world use, not just lab tests. As a supplier, I don’t oversell nylon as a replacement for every type of tubing, but I do make sure clients understand exactly what they’re getting: a material that might not have the highest light transmittance in a controlled lab setting, but that maintains its optical clarity in harsh conditions, makes bubbles and flow easy to see, and lasts longer than most alternatives, even when exposed to chemicals, temperature swings, and physical wear.
Over the years, I’ve had clients come to me thinking they need clear acrylic or PVC for their flow indicators, only to switch to nylon after their first batch of tubing arrived. The most common feedback? They can actually see what’s happening in the tubing better than before. That’s because the slight haze in nylon scatters light just enough to make small bubbles or flow patterns stand out, without being so high that it’s hard to see. And when the tubing gets scratched or scuffed from use (which is inevitable in industrial settings), nylon’s abrasion resistance means those scratches don’t ruin the optical clarity like they do on softer plastics like vinyl or acrylic.
If you’re currently evaluating tubing for a project and wondering if nylon’s optical properties will work for your needs, I’d encourage you to reach out. We can send you sample tubing of our clear, colored, and standard grades, and you can test light transmittance, bubble visibility, and long-term clarity in your own environment. I’ve worked with engineers to adjust extrusion parameters to get exactly the optical properties they need—whether that’s higher transmittance for flow monitoring or a slight tint to block UV light for sensitive fluids. Nylon is a versatile material, and its optical properties are just one part of why it’s such a popular choice across so many industries.
Don’t get me wrong—there are plenty of materials with better optical properties, but they come with trade-offs that make them impractical for most real-world applications. Nylon hits the sweet spot: it has optical properties that are sufficient for visualization and sensing, paired with the durability and flexibility that make tubing functional. For anyone who’s ever struggled with tubing that gets scratched, yellows, or loses clarity after a few months of use, nylon’s optical properties are a revelation. It’s not the flashiest material, but it’s reliable, and when you’re relying on tubing for your operations, reliability in both flow and visibility is everything.
Aluminum Foil Duct References
- Harper, C.A. (2002). Handbook of Plastics, Elastomers, and Composites. McGraw-Hill.
- Brandrup, J., Immergut, E.H., & Grulke, E.A. (1999). Polymer Handbook (4th ed.). Wiley-Interscience.
- “Optical Properties of Semi-Crystalline Polymers.” (2018). Journal of Polymer Science Part B: Polymer Physics, 56(12), 897-905.
- Nylon Tubing Material Properties and Application Guidelines. (2021). Society of Plastics Engineers (SPE) Industrial Division Technical Bulletin.
- Light Transmission and Haze in Extruded Thermoplastics. (2020). Plastics Design & Processing Magazine, 58(7), 32-35.
Dongyang Hstube Co., Ltd.
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