Interested in a little light reading?

Clarity is a critical aspect of liquid product quality in many industries, and modern consumers combine it with color when evaluating whether to buy a product or trust a brand. As a result, scientifically and objectively quantifying haze is essential to achieving quality goals and maintaining customer satisfaction.

What Is Haze and How Does It Alter the Appearance of Liquids?

In its simplest definition, haze is scattering of light produced by small particles in a sample. Suspended particles within a liquid also scatter light, leading to turbidity — a cloudy, milky, or opaque appearance.

Transmission haze occurs in transparent goods and liquids, like clear plastic preforms or bottled water. As light passes through the sample, factors like surface texture imperfections and impurities scatter the energy.

Primary Causes of Haze in Liquids

In liquids, a natural interaction between proteins and polyphenols usually causes measurable turbidity. Other potential causes include poor-quality raw ingredients, such as infected barley used in beer brewing or particulate residues from filtering processes.

The Importance of Haze to Consumer Perceptions

Clarity is necessary in liquids to signify quality and safety.

Turbidity in beer can be either desirable or undesirable, depending on the consumer's preference. Many manufacturers continually aim to control turbidity in beer since its presence can negatively impact taste and shorten shelf life. Others use turbidity as a competitive advantage, crafting hazy IPAs that consumers perceive as more flavorful. Similarly, some winemakers prefer haze as a marker of authenticity and a natural by-product of fermentation.

Other liquids also rely on haze to meet consumer expectations or generate a favorable customer opinion. For example, a haze in fruit juices can spur more sales by promoting the perception that nutritional value is higher. Manufacturers can create the haze naturally or use additives to produce the intended result.

Manufacturers of transparent plastics know all too well that haze can present challenges in achieving the desired outcomes. Too much scattering of the transmitted light produces a cloudy appearance that impacts consumer quality perceptions of quality and buying decisions. As a result, upholding consistent quality requires sophisticated tools that accurately and scientifically quantify color and haze.

Spectrophotometers inspect these attributes objectively, providing numerical values to compare. These devices help eliminate product appearance variations so you can regularly and effectively meet consumer expectations for quality.

Choose the Right Color Spectrophotometer

Benchtop spectrophotometers are ideal for measuring color and ensuring uniformity in plastic products. To ensure consistency, manufacturers should measure points across the entire range of production.

Using a spectrophotometer to measure the color of transparent sheet plastic offers several benefits, such as:

• Accurate data: Spectrophotometers provide reliable color data that reflects its actual color.
• Repeatability: These instruments provide a repeatable way to measure color, minimizing errors and facilitating consistent color throughout production.
• Standard compliance: HunterLab's spectrophotometers follow industry standards for color measurement, ensuring consistency across the supply chain.

Every material absorbs, reflects, or transmits light, which determines the color we see when looking at an object. Transmission refers to the light waves that pass through a translucent or transparent sample, and spectrophotometers provide quantitative measurements of that data. These devices make it possible to evaluate a sample's color scientifically and objectively, which is vital for ensuring color consistency in various applications. Spectrophotometer transmittance measurements enable better quality control and enhanced consumer perception of your products.

What Is Transmittance in a Spectrophotometer?

The definition of transmittance is the measured light that passes through a sample, meaning the light that is not absorbed or reflected. Three primary transmittance measurements include:

• Diffuse transmittance (Td, n): This measurement is the ratio of the flux transmitted by a specimen to the incident flux, with the transmitted flux being measured at all forward angles except the regular transmission angle. When light is diffusely transmitted, its direction changes as it passes through the material, causing scattering.
• Regular transmittance (tr, n): This measurement is the ratio of undiffused transmitted flux to incident flux. In other words, it is straight-through light.
• Total transmittance (tt, n): This measurement is the ratio of the flux transmitted at all forward angles to the incident flux. Total transmittance is the sum of regular transmittance and diffuse transmission.

These values are essential to maintaining quality in products like beverages and edible oils. It's best to measure color with a spectrophotometer to capture more accurate information, as these devices provide exact quantitative data regarding the amount of light that passes through a sample. 

The transmittance formula is:

T = PT/P0

The values in this formula represent:

• T: Transmittance
• PT: The source's radiation power as it exits the sample
• P0: The source's radiation power as it enters the sample

The resulting calculation is a ratio, comparing the light before it enters the sample to the light after it passes through it. A value closer to 1 means most light passes through, while lower values mean that less light passes through. 

What Is Percent Transmittance in a Spectrophotometer?

Percent transmittance displays the light that passes through the sample as a percentage rather than the ratio created by the above formula. You can get the value by multiplying the ratio by 100. 

A sample with 100% transmittance is transparent, allowing all light to pass through. Lower numbers indicate more translucence than transparency. At least 30% of the light must pass through the material for effective transmittance measurements.

The transmission percentage is also helpful for absorbance calculations. A commonly used absorbance formula is:

A = 2-log10(%T)

This formula determines the amount of light absorbed using the percentage of light that passes through the sample. 

Powders play a vital role in many industries, from food products like cocoa powder to minerals and the lifesaving medications pharmaceutical manufacturers create. Their colors must be consistent and meet customer expectations to support quality initiatives, conformance with industry standards, satisfaction, and, ultimately, profitability. Spectrophotometers provide the easiest, fastest, and most objective way to quantify color to help you reach these goals. 

Key Features to Evaluate

Learning what key features to evaluate as you explore the spectrophotometric solutions available can help you make a more sound investment.

Minimum Sample Sizes

Some ingredients, like certain high-value spices and active pharmaceutical components, are incredibly expensive. Reducing the size of the sample needed for accurate measurements is key to controlling waste and limiting sampling costs. A spectrophotometer that offers the smallest sample size possible will deliver the most value for many applications and significantly lessen the expenses involved with high-value powder production.

Sample Compatibility

Powders present unique challenges in color measurement. Many have nonuniform textures and varying particulate sizes requiring careful sample preparation to promote accurate outcomes. Their opacity demands specialized optical geometry that captures data through reflectance. A thorough, careful analysis of your powder's physical properties will help ensure the spectrophotometer's capabilities align with your needs.

Index and Scale Library

Many industries have specific industry scales or indices they use to ensure their products conform to standards. Samples may rely on different color spaces, such as the CIELAB scale often used to measure barium sulfate. Evaluate the spectrophotometers you're considering to ensure they're capable of providing data within the scales that apply to your industry.

Effective Bandwidth

Regardless of which wavelength you measure in the visible spectrum, you need to ensure the device you select has suitable effective bandwidth for accuracy. This term refers to the range of wavelengths interacting with a sample at a given moment. A narrow effective bandwidth coupled with high radiation throughput helps ensure strong signals and background noise reduction. This configuration allows for more precise readouts since the spectrophotometer can isolate smaller wavelength ranges.

Integration Capabilities

Ideally, the spectrophotometric solution you choose should fit effortlessly into existing workflows instead of forcing you to adapt proven processes. Features like universal compatibility simplify integration. This trait allows the spectrophotometer to connect to and communicate seamlessly with other devices. In addition, selecting a model with many connectivity options makes data export and transfer to your quality management systems fast and easy.

Viewing Area

While finer powders may lend themselves to a smooth, even sample surface, sample averaging is critical for measuring color in powders with larger particles and nonuniform characteristics. These traits can lead to shadowing that can create measurement discrepancies when only capturing data in one reading. Taking multiple measurements across larger viewing areas and averaging them helps resolve those challenges, so it's essential to consider viewing area size as you narrow down the options.

Spectrophotometers are invaluable to many industries, ranging from the food to plastics industries and beyond, delivering the color consistency necessary to streamline supply chain efficiencies and maximize product quality. The key to ensuring reliable performance and color measurement quality is knowing how to properly maintain a spectrophotometer.

What Is the Function of a Spectrophotometer?

A spectrophotometer scientifically measures the color of materials using a light source, wavelength-selective optics, sensors, and software to convert emitted energy to an industry-standard color scale. This measurement enables companies to verify the quality and consistency of their products, ingredients, and raw materials. The device mimics how the human eye sees color but eliminates error-prone manual visual observations for higher accuracy.

Best Practices for Using and Taking Care of Your Spectrophotometer

Spectrophotometers must undergo the proper routine maintenance to deliver the most precise and accurate measurements. With the right standardization and care, you can ensure your color spectrophotometer performs at its best.

1. Perform Routine Maintenance

A well-maintained device provides the most accurate and reliable readings. Maintenance begins with a thorough cleaning. No matter how well-calibrated your device is, it won’t deliver accurate or consistent readings if it isn’t clean. That’s why it’s vital to ensure your spectrophotometer is free of dirt, dust, grime, and other contaminants that can obscure measurement results.

When cleaning your equipment, it’s crucial to follow the best practices outlined in your user manual to avoid damaging the device and invalidating your warranty. Avoid using any harsh or abrasive tools or substances when cleaning your spectrophotometer.

Cleaning frequency varies based on the components. The exterior of the sensor and mounting generally require weekly cleaning. If your work involves messy samples that contact the sensor, you may also have to clean between measurements.

You should also consider your environment when determining cleaning frequency. For example, a unit stored in a dusty, poorly ventilated closet will require more routine cleanings than one contained in an air-conditioned office.

Other routine maintenance checks include:

• Inspecting and cleaning the power cord
• Verifying the optics are clean and in good condition
• Testing general structures like the device touch screen or buttons

Beyond these general checks, each model operates differently. Check the owner's manual for additional maintenance procedures specific to the device.

Plastic manufacturing has grown significantly since the 1950s, surpassing that of any other material. Today, plastics see use in markets ranging from automotive to goods packaging to food and beverage production. Plastic color is and will continue to be pivotal as the primary determinant by which consumers judge product quality and desirability, yet accurately quantifying it comes with unique challenges.

Common Challenges in Plastic Color Measurement

Typical plastic color measurement challenges include the following.

Natural Yellowing

Virgin plastic resins naturally yellow during processing as a result of oxidation. Additional yellowing can occur with age or exposure to ultraviolet rays. To achieve clear or almost clear end products, manufacturers must add optical brighteners that fluoresce on the blue side of the visible spectrum to negate the yellowness. That translates into almost all plastic goods containing at least some percentage of optical brighteners. As a result, these materials inherently fluoresce and introduce more complexity to achieving the desired clarity and visual chromatic qualities.

Regulatory Pressures

Government entities worldwide are passing ever-stricter regulations on the percentage of post-consumer recycled plastic that must be used in new plastic production to prioritize a more circular economy. An increase in the amount of recycled plastic used causes a corresponding rise in the amount of optical brighteners and other additives in feedstock that manufacturers must adjust for.

These challenges make accurate color measurements even more pivotal since one variation in the input can substantially impact the outcomes.

ESG Initiatives

In addition to governmental action, modern plastics manufacturers are feeling similar pressures from their stakeholders. Consumers, employees, and investors alike increasingly call for more sustainable practices and transparency in environmental impact.

To account for these pressures, many companies enact Environmental, Social, and Governance (ESG) initiatives that help achieve the six principles of a more circular economy. These pillars include minimizing waste, maximizing resources, saving energy, and reducing carbon footprint.

How to Resolve Color Measurement Challenges in Plastics

Fortunately, there are several steps you can take to resolve color measurement challenges with plastics production.

HunterLab’s Global Commitment: Stability, Service, and Support Amid Supply Chain Pressures

As global trade conditions continue to evolve, businesses across industries are navigating new levels of complexity. At HunterLab, we understand how these pressures can affect your planning, operations, and service expectations. That’s why we’re committed to ensuring that our color measurement solutions remain consistent, available, and fully supported — no matter the global environment.

For over 70 years, HunterLab has helped customers around the world maintain color quality with precision instrumentation and reliable service. In times of uncertainty, that commitment only grows stronger.

Why Global Conditions Matter in Color Measurement

Whether you’re formulating products in food, plastics, chemicals, or textiles, accurate color measurement is essential to brand consistency and quality control. But behind every precise measurement tool is a complex global supply chain — and today, that landscape is changing rapidly.

Businesses are feeling the effects of:

- Increased transportation costs

- Longer lead times due to port and customs delays

- Supply constraints for critical electronic and optical components

- Shifts in international trade policies and sourcing strategies

This environment has the potential to impact availability and cost structures across the instrument manufacturing industry. But at HunterLab, we are actively working to minimize that impact for our customers and partners.