Testing Guide: Difference Between Haze and Transmittance

How do you ensure your transparent materials look absolutely stunning?

Whether you are manufacturing crisp packaging or high-tech screens, nailing that perfect optical clarity is the best way to impress your customers. At Qualitest, we believe the rising bar for quality is actually a massive opportunity for manufacturers ready to step up.

To get there, you simply need to grasp two critical concepts: haze and transmittance. These metrics are often mixed up. However, understanding the specific difference between haze and transmittance is exactly how you take your product from good to exceptional.

Key Takeaways

- Distinct Metrics: Transmittance measures the total amount of light passing through a material. Haze quantifies the scattering of that light which causes a cloudy appearance.

- The Clarity Paradox: High light transmission does not guarantee a clear image. It is possible and often intentional to have materials with both high transmittance and high haze levels.

- Standard Compliance: ASTM D1003 remains the gold standard for North American plastics testing. Adhering to this specific protocol is essential for valid quality control data.

- Source of Error: Most data inconsistencies arise from improper sample handling or lack of flatness rather than device malfunction.

- Cost-Effective Accuracy: You do not need expensive benchtop units for precision. Portable haze meters now offer laboratory-grade results compliant with ISO and ASTM standards.

What is Transmittance?

Let’s discuss Transmittance first. It sounds complex, but it is effectively a straightforward percentage. If a material possesses 100% transmittance, it permits every photon of incident light to pass through. If it registers at 0%, you are looking at an opaque barrier.

Consider a freshly polished windowpane. Its primary function is to admit sunlight. When we evaluate for transmittance, we are asking a simple question: "What volume of light is traveling from one side to the other?" regardless of whether that light is scattered or travels in a straight line.

In our honest assessment, transmittance is the straightforward metric to comprehend, yet it provides only a partial picture.

What is Haze?

Haze is the complicated variable. This metric does not concern how much light passes through. It quantifies the fraction of transmitted light that is scattered and deviates from the direct path, causing a cloudy or diffused appearance.

Haze meters typically assess this scattering by measuring light deviation beyond a small angle (e.g., 2.5°) from the incident beam, distinguishing haze from simple absorption or reflection losses (Molloy et al., 2023).

Significant haze results in a milky, foggy, or blurred aesthetic. To illustrate precisely what we mean:

- The Intentional Haze: Think of an anti-glare laptop screen. It uses a specific, engineered amount of haze to diffuse reflections without destroying readability.

- The Unwanted Haze: Picture a plastic water bottle that looks "dusty" or "milky" inside the plastic itself. That is a manufacturing defect.

We frequently advise our clients that haze is the silent destroyer of perceived quality. You might possess a material that admits a massive amount of light (high transmittance) but scatters it broadly (high haze), rendering the visual experience blurry and unappealing.

The Cheat Sheet: Haze vs. Transmittance

To assist you in visualizing the difference between haze and transmittance, we have expanded this breakdown to include real-world applications where these numbers matter:

The Paradox: Can You Have High Transmittance AND High Haze?

Here is where the situation becomes interesting. We are convinced that comprehending this specific paradox is exactly where superior R&D teams distinguish themselves from the average.

One common fallacy is that haze and transmittance always oppose each other. That is incorrect. Therefore, transmittance and haze describe different optical phenomena and can coexist at high levels depending on the material's structure and composition (Pan et al., 2023; Hsieh et al., 2017; Molloy et al., 2023).

Research confirms that materials can transmit a large portion of light while strongly scattering it to create diffuse transmission (Hou et al., 2020; Lim et al., 2018; Pan et al., 2023; Hsieh et al., 2017).

- Advanced Optical Applications: This is seen in materials like transparent wood and cellulose films designed for optical applications, which achieve transmittance around 90% with haze values also near 90% or higher (Hou et al., 2020; Hsieh et al., 2017).

- Performance Enhancement: Such properties are valuable in applications like solar cells and displays, where diffuse light improves performance by reducing glare and enhancing light management (Hou et al., 2020; Lim et al., 2018). The high haze arises from microstructural irregularities or refractive index differences within the material that scatter light without significantly reducing overall transmittance (Hou et al., 2020; Hsieh et al., 2017).

If you fail to track the difference between haze and transmittance, you risk approving a batch that technically passes a "light transmission" test but looks unacceptable to the human eye.

The Standards: ASTM D1003 and ISO 14782

To maintain consistency, industries depend on established rules.

- ASTM D1003: This is the dominant standard in North America for plastics.

- ISO 14782: This is the international equivalent focusing on haze determination.

We consistently recommend our North American partners prioritize ASTM D1003. While global alignment is positive, ASTM remains the definitive benchmark for domestic compliance. Executing these tests demands equipment that can handle the rigor without faltering.

3 Technical Tips for Accurate Measurement

Acquiring precise data isn't magic. It is about rigorous process control. In our experience, the majority of inconsistent data stems from improper sample handling, not equipment failure.

Here are three protocols we recommend:

1. Ensure Sample Flatness: If your film has even a microscopic gap or wrinkle, your readings will be inaccurate. We engineered our QualiHaze QH-Series with specialized fixtures to secure films perfectly flat.

2. Maintain Strict Cleanliness: A single fingerprint scatters light significantly. Always manipulate samples by the edges.

3. Automate Calibration: Standards like ASTM D1003 are strict. Our portable units perform a self-diagnosis immediately upon startup. We believe calibration should be automatic, as manual adjustments are an unnecessary burden.

Reliable, Cost-Effective Testing with Qualitest

We are going to be frank. Too much laboratory equipment is prohibitively expensive. We decided to alter that dynamic. You should not be forced to choose between acquiring precise data and maintaining your budget.

Our QualiHaze QH-Series is the solution. It offers the precision of benchtop units with the utility of a portable device. Whether you are testing mobile phone cover films or plastic sheets, this instrument delivers.

We offer models like the QH-10, QH-12, and QH-13, featuring:

- Dual Optical Paths: Ensuring consistent repeatability (≤0.02).

- Touchscreen Interface: A clear 2.8-inch display for effortless reading.

- Multiple Apertures: Options ranging from 12mm to 21mm to accommodate various sample sizes.

- Cost-Effectiveness: Professional accuracy at a price point that makes sense.

By utilizing the correct technology, you ensure that your distinction between haze and transmittance is always correct, protecting your brand's reputation.

Ready to Upgrade Your Quality Control?

Do not allow cloudy data to compromise your product quality. We believe every facility deserves access to superior testing without the exorbitant costs.

Seriously, what kind of quality professional would ignore a tool that streamlines their process this effectively?

Check out our Portable Haze Meter today to see how we can assist you with cost-effective, high-performance solutions. Contact us for technical discussion—we are here to help you secure your material testing objectives.

References

- Hou, G., Liu, Y., Zhang, D., Li, G., Xie, H., & Fang, Z. (2020). Approaching Theoretical Haze of Highly Transparent All-Cellulose Composite Film.. ACS applied materials & interfaces. 

- Hsieh, M., Koga, H., Suganuma, K., & Nogi, M. (2017). Hazy Transparent Cellulose Nanopaper. Scientific Reports, 7. 

- Lim, Y., Kwon, O., Kang, S., Cho, H., Lee, J., Park, Y., Cho, N., Jin, W., Lee, J., Lee, H., Kang, J., Yoo, S., Moon, J., & Bae, B. (2018). Built‐In Haze Glass‐Fabric Reinforced Siloxane Hybrid Film for Efficient Organic Light‐Emitting Diodes (OLEDs). Advanced Functional Materials, 28. 

- Molloy, E., Koo, A., Gevaux, L., Obein, G., & Yang, L. (2023). Use of bidirectional transmittance distribution function measurements to determine transmittance haze. Metrologia, 60. 

- Pan, R., Cheng, Y., Pei, Y., Liu, J., Tian, W., Jiang, Y., Tang, K., Zhang, J., & Zheng, X. (2023). Cellulose materials with high light transmittance and high haze: a review. Cellulose, 30, 4813 - 4826.