Application Notes and FAQs

Plastic pellets come in many different shapes, sizes, gloss, and translucency. In this study we compared the measurements of various pellets on three benchtop instruments.  The pellets were measured in HunterLab sample cup (HL# 04-7209-00).  The pellets were poured into the sample cup to to the top (50 mm height) to conform to ASTM D6290. Each sample was measured on all instruments, and then poured and remeasured a total of 5 times.

The variety of pellets tested are shown below.

The results of the measurements are shown below

Color is an indication of quality and freshness of spices, that is why maintaining color accuracy and consistency in spices is important for appealing and responding to today’s customer’s needs. Therefore, special spectrophotometers with the right accessories and presentation techniques are essential to ensure uniformity and more repeatable results during measurement.
HunterLab in the past developed ColorFlex EZ as one of the standard instruments to measure the reflectance of spices. However, as spectrophotometric technology has advanced in recent years, and as our customers’ needs changes over time, HunterLab developed new innovative spectrophotometers that requires less sample prep and are designed specifically to move the sample under the sensor without touching the sample surface. This increases the measurement area of the sample.

Results of the study can be downloaded from the link below.

Posted on November 27, 2018 by Ganesh Ramanathan

Coconut water is a multi-billion dollar industry that is expected to expand globally to US$8.3 billion by 2022.¹ Consumers have been drawn to coconut water’s sweet, refreshing taste and unique chemical composition, similar to blood plasma, which is rich in carbohydrates and important nutrients such as magnesium, calcium, and phosphorus.¹ These nutrients also make coconut water a naturally rehydrating sports drink which has increased market appeal. Fresh coconut water from young, green coconuts is particularly valued for a delicate taste and increased antioxidant benefits.

When first poured from the coconut shell, coconut water is a clear, colorless liquid that can be combined with the interior pulp for additional texture and variety. Color changes can occur in harvesting, cracking, sterilization, and storage processes so the final beverage can fluctuate from translucent white to pale yellow and even bright pink.¹ Products can also include varying levels of pulpin the liquid depending on geographical region, harvesting practices, pasteurization, and market targeting, such as coconut beverages which are sold with pulp.

Sold coconut water’s final product is a combination of the color and pulp concentration, or turbidity of the water. With so many different variables, it can be challenging to maintain a consistent product. However, Hunter Spectrophotometric technology, with innovations in color and haze measurements, can offer innovative solutions for measuring both color and haze in a single reading of coconut water for consistent, reliable production. The Haze measurement can be substituted for a turbidity measurement done on a separate instrument.

DIFFICULTIES OF CONSISTENT COLOR AND HAZE IN COCONUT WATER

 When your customer picks up a cooled bottle of coconut water from the store refrigerator, what they see through the plastic is a combination of color, usually light white to pale yellow, and pulp concentration. Strolling down the beverage aisle, there are many different brands of coconut water, each with a reliable, consistent appearance to build brand trust with their customer. But from shell to bottle to store, a consistent appearance isn’t so simple, as multiple variables, including chemical properties, harvesting and storage methods, and product differences, influence the final product.

These difficulties begin with the coconut. Since coconut water has a high pH, varying from 5 – 5.4, it is subject to rapid deterioration and fermentation once exposed to oxygen.¹ Young coconut water, which is harvested one month earlier than mature coconuts, has a lower pH but higher phenolic content, as well as greater polyphenol oxidase (PPO) and peroxidase (POD) enzyme activity. The increased phenol content raises antioxidant levels and health benefits,, but higher PPO and POD also raises the water’s susceptibility to oxidation¹ Within minutes of first cracking, yellow, amber, brown, or even pink discoloration can bloom across the harvested water’s surface.

To keep the water from spoiling early, whole nuts are gently harvested and stored for up to six days till extraction inside the plant. But new challenges arise with processing. During cracking and harvesting, coconut water can become cloudy from the accidental shell and coconut meat debris, or by adding pulp for a pulped coconut beverage. Once harvested, coconut water must quickly be sterilized and bottled which can also cause changes in the coloring.  To prevent this, conventional thermal techniques, as well as cooling, freezing, or adding stabilizing juices such as pineapple, are quickly used to prevent further discoloration.² In spite of these prevention methods, if the storage space is not properly temperature controlled, then discoloration can occur in storage and transportation to the store.

With all these different variables, the challenges of delivering a consistent coconut beverage can seem high. Consistency and reliability however, are the cornerstone of branding in a saturated market. It is also distinctly important to have a consistent color and haze for naturally harvested products to develop consumer trust.

MEASURING COLOR AND HAZE IN COCONUT WATER

From harvesting, sterilization, production, and storage, different colors and concentrations of pulp can compose the final coconut water product depending on the batch. To accurately gather the appearance of your coconut water batches for crafting a consistent final product, both color and pulp concentration need to be measured. Using a Turbidimeter is often used in liquids to measure pulp concentration, but with coconut water, different batches can have different levels of turbidity. These varying levels can interfere with an accurate, consistent color reading.⁴

Haze% measurement is a method that can be used to accurately measure coconut water pulp. Haze% is a proven method to measure light scattering from a translucent liquid, rather than reflectance. Haze% measurement is calculated from the pulp concentration in coconut water, or the particles visible by the human eye, which also captures the clarity of the sample as clarity increases as pulp decreases. This is ideal for coconut water measurement as it allows you to gauge a product based on what your customer actually sees.

Haze% can also be correlated to color, as the color that a customer sees on the shelf is a combination of the color of the liquid and the pulp concentration. Calculating Haze% and correlating to color measurement had reproducible appearance results, which means that a correlation between the two can be established for a consistent brand color-haze standard across different batches. Haze%, and its capacity to measure for optimal visual appeal is an innovative measurement for the most important visual factors in coconut water production.

VISTA: A NEW STANDARD FOR MEASURING COCONUT WATER

HunterLab’s Vista is a revolutionary transmission color and haze spectrophotometer uniquely suited for the challenges of measuring coconut water. Vista is designed for the simultaneous measurement of color and haze of transparent liquid and solid sample for valuable correlation insight. Vista’s unique design allows or scientifically reproducible results that can be used to help eliminate any variables in coconut water harvesting, production, and sterilization, creating a new industry standard for excellence.

As an advanced transmission spectrophotometer, Vista can measure a variety of sample sizes from standard 1cm x 1cm cuvettes to 10cm by 10cm cells. Vista’s EasyMatch Essentials software for Vista includes virtually every transmission color, haze scale, and index available, including the APHA/Pt-Co-Hazen Color Scale, the Gardner Color Scale, Haze %, Opalescence, Y Total Transmission, CIE Spectral Data, and all 3 Major Pharmacopoeias – US, EU, and Japanese. With storage capacity for thousands of readings and all major color and haze measurements, Vista can be used for a dual color-haze standard for your coconut water brand, a notable advantage for standing out in growing markets.

Full article with photos available here:

https://www.hunterlab.com/blog/benchtop/consistent-measuring-of-coconut-water-color-and-haze/

Posted on November 15, 2018 by Ganesh Ramanathan

Color and appearance measurements for the beverage industry are used to ensure that the overall product appearance is the same from lot to lot. In the marketplace, it is rare that consumers are permitted to taste food products prior to purchasing them. However, they frequently can look at the product. They make a judgment decision largely based on overall appearance including color.

Coloring the mind of your Consumer:

Never has the consumer been more empowered than now in this digital age where knowledge of the products they purchase has been made available to them at a click or swipe, and this testifies that a greater need has evolved for the F&B industry to build a product with enticing visual properties such as Color and haze without compromising the highest level of quality. A strikingly similar parallel of ‘Go-Green’ campaign has also weaved it’s way in the Food & Beverage industry influencing the consumers to choose  naturally colored products over artificially bright and unnatural Colored products, and this has birthed the need to test the quality of the beverage for Color consistency across all stages of the process like production and storage as the ingredient changes can alter the base color of a beverage, resulting in the perception that the product is different or of lower quality.

Diverse Optical Characteristics and their Methods for measurements:

The complexity of successfully measuring Color and appearance in the Beverage Industry is further enhanced by the fact that beverages are of types opaque, translucent or transparent, and each form requires different instrumentation and techniques. Opaque liquids have high solids content with a characteristic of high Brix value when light passes through it and Translucent liquids possess medium levels of solids and exhibits a lower brix value when light passes through it. Therefore, it is crucial for the food processors to assess the right measurement modes like reflective or transmittance before they measure the Color during any stage of processing. This significantly increases the need of a spectrophotometer to measure the spectral data values and also measure the transmission haze.

Maintaining Color through various food processes:

Food and beverages are highly volatile as they tend to change Color during production, transportation and even in storage. The cost and labor of adjusting a food or beverage Color in its final stage of production is very high and hence the Color consistency must be measured at each stage of the production.

Additionally, the Food & Beverage Regulatory bodies stress the importance of maintaining product specific Color standards in the industry through their elaborate regulations. This makes the measurement of Color and haze to maintain high degrees of Color quality a top priority for the Producers, also accentuating them towards protecting their license to operate.

Thus, this makes the use of Spectrophotometers essential as it addresses both the challenges of meeting regulations and the capability to measure Color and Haze during any stage of the production process.

Full article with photos available here:

https://www.hunterlab.com/blog/color-food-industry/a-better-method-of-measuring-color-and-haze-in-beverages/

Posted on October 29, 2018 by Marissa A.

The use of essential oils is a growing trend within the health and wellness community. The therapeutic properties of these oils have been recognized and harnessed by practitioners of traditional medicine for centuries, but they have become increasingly appealing to patients, clinicians, and researchers who are looking for all-natural treatments. Indeed, studies suggest that essential oils are remarkably versatile, capable of everything from promoting relaxation to fighting skin infection to combating cancer.¹

While it is clear that essential oils offer a variety of health and wellness benefits, one drawback of these compounds is that, by volume, they are extremely expensive. This can become a particular problem for essential oil manufacturers who are developing strategies for process monitoring and quality control. Given the high investment cost, it may not seem wise to test for certain properties, such as color. However, today’s spectrophotometers can enable manufacturers to overcome this problem by offering the opportunity to measure color using smaller sample sizes.

Controlling Costs for the Company and the Consumer

Essential oils are highly concentrated plant extracts, so only a tiny amount is needed in order to achieve a particular therapeutic purpose. Nevertheless, because of the complexities of the process of distilling these products, even a small quantity bears a high cost. For manufacturers, this means that each color measurement during the essential oil preparation process represents a considerable investment in terms of both financial expenditure and material resource loss. This can make it tempting for some companies to forego color measurement altogether.

At the same time, when considering the issue of consumer preference, it has never been more important for essential oil companies to guarantee color consistency. Consumers have become increasingly aware of the potential safety hazards of using essential oils, knowing that they offer significant opportunities to enhance health and wellness, but that these compounds’ high potential for toxicity can lead to major problems if things go wrong.² However, since most users aren’t experts, they have little choice but to opt for the simplest evaluation method: visual inspection. A customer may become concerned if they notice inconsistencies in essential oil color. Therefore, adherence to consistent color can help essential oil companies maintain trust with their customer base.  

In order to balance the cost of measuring the color of expensive essential oils with the need to maintain a consistent color, today’s manufacturers can take advantage of instruments that measure small volumes. Due to advances in spectrophotometric technology, a number of modern spectrophotometers are now compatible with sample holders that hold smaller amounts of a product than could be analyzed by traditional spectrophotometers. As such, it becomes financially feasible for essential oil manufacturers to take the necessary measurements, both during and after the manufacturing process. Put simply, the ability to get an accurate color measurement for a tiny amount of an essential oil can completely upend the traditional cost-benefit analysis when it comes to making spectrophotometric measurements for these products.

Full article with photos available here:

https://www.hunterlab.com/blog/color-pharmaceuticals/measuring-the-color-of-expensive-essential-oils-using-smaller-sample-sizes/

Posted on October 24, 2018 by Marissa A.

The market for non-dairy milk made from almonds, cashews, and other nuts is growing rapidly; non-dairy milk sales have increased by 61 percent since 2012, and sales are expected to continue to grow over the next few years.¹ To cater to this popular market, non-dairy milk manufacturers must ensure that their products are high in quality and consistent in color. However, according to a 2015 Global Health and Wellness survey, most consumers reported that they are more likely to buy products that contain no artificial colors, preferring all-natural ingredients instead.² This poses a challenge for nut-based milk manufacturers. How do you produce consistent-colored products without the use of artificial colors?

To offer all-natural products to consumers, many manufacturers are turning to spectrometry to test their products for color consistency and refine their manufacturing process. By measuring the color of your almond milk or other nut-based milk products using a spectrophotometer, you can create more consistent batches of milk without relying on artificial coloring agents to create visual appeal.  

Creating Consistent-Colored Almond Milk

When you manufacture almond milk and other nut-based beverages, achieving precise color consistency across multiple batches can be challenging.³ Each step of the manufacturing process can cause color variations in your product, including:

• Sorting: Although peeled almonds are naturally more consistent in color than raw almonds that still have the skin on, you should still analyze your raw, skinned almonds and remove any that fall outside of your color standards in order to achieve color consistency in your milk products.
• Soaking: During the soaking stage, color consistency can vary significantly between one batch of raw almonds and another. Additionally, if you leave the skin on the almonds, your milk product will be darker in color and it may be more difficult to achieve color consistency.
• Blending: When you blend your almonds and add flavors to the mix, the color of the almond beverage may change again, as added flavors like vanilla extract can impart a brown color to the product. You may choose to measure the color of your product once again at this stage in order to maintain color standards.
• Filtering: Inadequate filtering may leave solid particles in the milk, impacting appearance and consistency.
• Pasteurization and other treatments: Pasteurization or ultra-high pressure homogenized (UHPH) treatment processes eliminate bacteria and extend the shelf life of the product.⁴ During this stage, you should look for signs of discoloration in your product. That’s because the treatment techniques used to extend the shelf life of almond milk can impact the color of the product; for example, UHPH treatment typically produces milks that are lighter and more stable in color than pasteurization.

By testing the color of almond milk and other nut-based milks spectrophotometrically throughout the manufacturing process, you can tailor your processes to create the color you want and retain color consistency from batch to batch. A spectrophotometer can help you detect slight variations in color at every step, allowing you to address the color issues immediately through UHPH, additional filtering, or stricter nut sorting protocols.

How to Test Your Nut-Based Milk Products for Color Consistency

In order to test the color of your nut-based milk products during the optical sorting stage, the blending stage and the pasteurization, or UHPH stage, you need to use the appropriate spectrophotometer for each task.

Testing the Color of Solid Ingredients

To test the color of your raw nut ingredients in solid form, you need to use a non-contact spectrophotometer that is capable of measuring the color of irregularly-shaped samples. The Aerosspectrophotometer may be the best option for your lab because it is specifically designed for non-contact measurement of textured products like raw almonds and other nuts. Notably, this instrument provides the largest sample area measurement the in the world, allowing you to analyze much larger sample sizes than any other spectrophotometer. This is important when you manufacture nut-based milk beverages, as a large sample of nuts will be a more accurate representation of the entire batch that you plan on using in your final product. Alternatively, if you want to integrate color measurement within the processing line itself, the SpectraTrend HT may be the perfect choice for your facility. The SpectraTrend HT is an on-line spectrophotometer that continuously monitors color in real-time, eliminating the need for time-consuming sample preparation and streamlining the quality control process.

Testing the Color of Liquid Samples

Some manufacturers receive consistent-colored raw nut ingredients in bulk from manufacturers that perform their own color quality control on their products. As a result, you won’t have to test your raw ingredients for consistency in advance. However, all almond milk manufacturers need to use an instrument that can measure the color of samples in a liquid state, such as the UltraScan VIS. The instrument measures both reflected and transmitted color, allowing it to handle samples that range from completely opaque to transparent.

The UltraScan VIS spectrophotometer is engineered for extraordinary accuracy and precision. When the instrument is operated in reflectance mode, it can provide unprecedented insight into the color of opaque milks and confirm that your products fall within a specific color tolerance. The UltraScan VIS is also a great choice for measuring the color of translucent milks, as it is a CIE-conforming sphere instrument that eliminates the effects of light scattering in a semi-transparent liquid. Using this instrument, you can get accurate results regardless of the opacity or transparency of your products.

Full article with photos available here:

https://www.hunterlab.com/blog/color-food-industry/spectrophotometric-color-measurement-helps-eliminate-artificial-colorants-in-almond-milk-and-other-nut-based-beverages/

Question : Does the L*a*b* value influence the Haze reading, for example do darker colors (low L*) also have lower Haze than lighter colors ( high L*) or is this an over simplification.

Answer:

%Haze is a physical attribute that is unrelated to the color of the specimen being measured. When light is collimated at 90 degrees through a transparent object it can either be transmitted through the object without changing angle, or it can scattered at angles other the incident angle. %Haze is equal to 100 times the quotient of the scattered light divided by the sum of the scattered light and incident transmitted light.

Imagine reading a newspaper through a pair of eyeglasses have nearly perfectly clear lenses. These lenses if measured would have an L* in the 92 to 95 range and a % haze value close to zero. Now consider if you had to read the paper by looking through a polyethylene sandwich bag. The sandwich bag probably has an L* close to 90 but with a %Haze in the 20% to 30 %Haze range or higher. Still clear enough to read but the type and photos would appear slightly fuzzy. Now put on a pair of dark green sunglasses. L* in the 30 range, %Haze close to zero. That type and photos would take on a green hue due to the lens color but would appear as sharp as when you were wearing the clear lenses.

Question:

I was asked during a recent audit to provide a calibration and traceability certificates for the black glass I use to calibrate my 45:0 instrument. I said that none were provided when I purchased the instrument. Why were they not provided?

Answer:

We follow the ASTM E1164 Standard Practice for Obtaining Spectrophotometric Data for Object Color Evaluation. The full text of ASTM E1164 is available for purchase from the www.ASTM.org

Referring to section 10.2.1 which states that the Full Scale Standardization shall be done using a White Reference Standard calibrated relative to the perfect Reflecting diffuser. This implies that the White Instrument Standard has unique calibrated values which would need to be substantiated by a Calibration and Traceability statement.

Referring to section 10.2.2.1 for 0:45 and 45:0 Zero Scale Standardization shall be done with "a highly polished black glass standard with an assigned reflectance factor of zero." This implies that for any highly polished black glass the reflectance factor is zero at all measured wavelengths. There is no calibration required to assign the reflectance factor at each wavelength. The reason why no calibration is required is that except for a few very expensive instruments maintained by the NMI's of the world the true reflectance of polished black glass is many magnitudes below a commercial instruments ability to measure it.

Question: We recently purchased a set of calibrated tiles and would like to know the expected inter-instrument agreement between all of the HunterLab sensors our company uses to measure the color of our product.

Answer:

The most widely accepted method of using CCSII tiles (Lucideon/Ceram/BCRA 12 Glossy tiles) is to create a target for each color from the mean of the population readings of the sensors in your company. Then periodically read the tiles and record the color difference (dE* or CMC or dE2000) for each tile from its target value. Then calculate the average of the 12 color differences. If the average is less than 0.15 then the instrument is considered acceptable for use. You may also wish to bound the set with a maximum allowable color difference ( e.g. no individual color difference greater than 0.30)

There are many other ways that these tiles are used, such as separating the performance reading the 4 gray tiles from the performance reading the colored tiles or calculating the recording the color differences between reading the Gray and Difference Grey and Green and Difference Green tiles.

Question:

What is the difference between Lycopene versus Fresh Tomato Color Index (FTCI)

 Answer:

Lycopene Index and Fresh Tomato Color Index are very different and have specific uses.

Fresh Tomato Color Index is fixed for all users.

Fresh Tomato Color Index FTCI = (100((21.6/L) - (7.5*b/(L*a))) using the Hunter L, a, b color scale for C/2 conditions. 

There is no universal "Lycopene Index". While there are correlations cited in literature, they are all dependent on the method of sample preparation and measurement which varies from publication to publication. Effectively each user establishes their own "Lycopene Index".

CMR3098 offers the following equation for the calculation of Lycopene Index.

Lycopene Index (mg/kg) = (a/b – Offset)/Gain

where

 gain is user-editable = 0.0039 as default

 offset is user-editable = 0.3319 as default

 a/b ratio is determined from Hunter a and b color values, fixed for C/2 conditions.

The user is expected to determine their own gain and offset if they want to more closely HLPC or spectrophotometric transmission measurements.

FAQ: " I have a customer who wants to measure something called 'Neat Color' at a temperature of 150°C.

They have seen that in the US, a company is doing this using a Hunterlab instrument with “SpecWare Version 1.10 + Brass sample holder with slots 10 mm apart for glass slides and microscope slides, 3x2” glass”

Do you have any idea which instrument this is?"

To the best of my knowledge, there is no color scale called "neat".

Instead what I think it refers to is measuring the color of the material neat, meaning undiluted. More than likely this is some type of chemical concentrate (often crystals or pellets) that has to be heated undiluted to 150 C to make it into a liquid where the color, typically APHA/Pt-Co or Gardner, is measured as an indication of color quality.

Here is a note on how we generally approach hot liquids - Measuring Hot Liquid Samples - AN 1030.00

Specware was HunterLab's legacy DOS color software. The brass device sounds like a custom sample holder.

If you can find out any more information, we can better advise.

Our technical staff realized that:

a) the white tile data are located into the instrument firmware (all the instruments?)

All HunterLab instruments have their calibrated white tile data stored in ROM on the Signal Processing (SP) or Data Aquisition (DA) board. When the instrument is powered on this data is moved to RAM.

b) the white tile data can be entered by a sw

The user software EasyMatch QC has no ability to load white tile data to ROM

The Diagnostic software supplied with each instrument does have the capability to load white tile data to ROM.

But it is not fully clear how these values are used in the calibration and

in the measurement routine.

During Standardization the following two terms are created Instrument Dark ( spectral result of measuring Light Trap or Black Glass ) and Standard White (spectral result of measuring Instrument White Tile )

When the user reads a Sample the value for the sample reading shown on the screen is calculated from the following formula;

Sample Value = ((Sample reading minus Instrument Dark) divided by (Standard White minus Instrument Dark)) times Calibrated White values

This formula is the same for all current color spectro manufacturers.

By considering for example the MSEZ and CFEZ units (stand alone mode), if

the customer changes the white tile (once bought the option L02-1014-418),

what will happen to the measure values stored in the instrument (sensor)

database?

Nothing happens to the data stored in the database. There is no reason to change that data.

Are the measures stored still valid?

Of course, what would invalidate them? The white tile that HunterLab labels instrument white standard is directly assigned relative to PTFE. The difference between white tiles is much less than the difference between individual instruments.

There is any kind of correlation with the new white tile data by

preventing any drift to them?

I don't understand the question, do you mean "difference" instead of "drift". Drift means that the value slowly changes. Difference means that the is immediately not the same.

In case of double measure on the same sample before and after the white

tile change, would you confirm the reliability of the measured value? What

kind of DE we may expect?

Less than inter-instrument agreement specifications.

Considering one of your instruments (sensor) connected to the software

Easy Match QC how do you manage the white tile data?

Since EashMatchQC has no ability to alter the ROM in the instrument it has no ability to manage the white tile data.

To be more specific, what might happen to my data (stored in the Easy

Match sw) in case of white tile replacement?

Nothing happens to the stored data. Why would you think that the stored data would change?

Does the sw use the white tile data stored in the instrument firmware? If

yes in which way?

In the equation described earlier where the ((Smp-Drk)/(Std-Drk))*Calibrated data the Calibrated data comes from the instrument firmware.

We noticed that the white tile of the instrument (sensors) are different

from Msez,Uvis and Cfez, is there a specific reason?

MSEZ, CFEZ, STHT, D2NC use a porcelain enameled steel white tile as their top of scale standard, this tile has curve shape that mimics TiO2 and average reflectance greater than 85%, the USVis and USPro use an EverWhite Japanese Opal tile as their top of scale, this tile has a curve shape that mimics PTFE and average reflectance greater than 95%.

Could You please send us a program to see how it uploads the white tile

data into the firmware?

See attached instructions on how to load White tile data into an LSXE using LSXEDiagnostics software. This basic procedure is the same for all of the different diagnostics programs. Also attached is a sample White tile data file. these files have the extension .rfl and are typically named with the instrument serial number.

Many thanks in advance for your kind commitment,

Have a nice week end

Piermario

Cordialità / Best Regards

What is the best way to measure the effects of UV optical brighteners in our samples with our HunterLab instrument?

The recommended method is a two-part measurement sequence. The first measurement mode you will need to setup is the UVF Calibrated (UV included) mode. This mode will provide some UV content but will provide a consistent amount of UV content. The second mode you will need to setup is the UVF In (UV Excluded) mode. This mode will effectively exclude all UV content of the lamp.

After you take your two measurements in UVF Calibrated and UVF In you will then need to compare the significant indices you are concerned with for your product. For some customers this might be a L* value, a b* value, or maybe a WI index; this will be personal and depend on what your facility has established as a meaningful metric.

It is important that the UVF Calibrated mode is used because UV content in a lamp will vary from instrument to instrument and is affected by several factors. By using UVF Calibrated you are using a consistent UV content that will stay consistent as the lamp in your instrument ages. These settings could also be applied to different instruments should you upgrade down the line.

Repeatability test tells us the condition of the lamp flash system and electronics independent of color accuracy. Didymium filter test tells us the wavelength accuracy of the instrument independent of reflectance color accuracy. When taking a measurement the integrating sphere interior wall mixes and homogenizes the light reflected from the sample. The wall coating is a critical part of the process, as much as the wavelength alignment and repeatability of the measurement process. the Green tile is a single color in the middle of the wavelength range and middle of the linearity range. It does a good job of predicting the general color accuracy performance of the instrument. The full Color Tile readings are done when the first two tests are successful and provides a "stress test" of color accuracy by using tiles that represent a fairly complete non-chromatic and chromatic color range. The tiles Red, Orange and Yellow have the lowest reflectance in the range from 360 to 600nm of all of the tiles in the set. Dirty lenses causing diffusion can affect the low reflectance readings as can sphere wall dulling, or aging.

EP 2.2.1 Defines three instrumental methods

1. Nephelometry - View the specimen at right angles ( 90 degrees ) to the direction of incident light. Use for NTU values less than 1750 to 2000 units.

2. Turbidimetry - A property of the specimen's ability to scatter or absorb light as opposed to transmitting it in a straight line through the sample.

3. Ratio Turbidimetry - ratio of the transmission measurement to the 90 degree measurement

HunterLab does not offer 90 degree detection, so technically we only fully conform to a Turbidimetry measurement, but EP 2.2.1 says "Instruments with range or resolution, accuracy and repeatability capabilities other than those mentioned above may be used provided they are sufficiently validated and are capable for the intended use." So any instrument may be used as long as it is validated.

There are some samples that can only be correctly measured using Nephelometry, but HunterLab has been able to show valid correlations to Opalescence and lower NTU units when creating calibration curves using our benchtop transmission capable instruments.

See an05_07 for a method to validate HunterLab instruments.

[Opalescence - an05_07](https://support.hunterlab.com/hc/en-us/articles/203995865-Opalescence-an05-07)

Question:

ISO 17025 accredited lab and would like to know if there is any type of annual calibration that would be needed to maintain this equipment.?

Answer:

The calibrated specimen supplied with the sensor is the White Instrumetn Tile. This was supplied with Certificate of Traceability showing both the calibrated values and the uncertainty of the calibration ( for all expect LSXE and CQXE ). An expiration date is not shown on this certificate, individual users typically choose a timeframe of between 12 and 60 months to have this tile recalibrated.

Color Measurement is a unique field in metrology since there are no intrinsic standards of color expect for White. To compensate for the lack of intrinsic color standards the industry has standardized on using Lucideon CCSII tiles as consensus standards of color. Since color measurement is device dependent HunterLab has created targets based on the mean of group of known good sensors and uses these values to validate the color measurement performance of an instrument that was standardized using a calibrated Instrument Standard White. If the instrument can read back these CCSII tiles to within the stated uncertainty for the tile and tile set then it is implied that the instrument falls within the population mean of the instrument family.

Your sensor was shipped with a copy of its factory verification. We recommend that you have this type of verification performed at not more than 15 month intervals.

We currently have not listed any printers as an accessory on the Price List.  The goal is to support all of the major brands for printers and there are drivers available that are pre-loaded on the Vista.  We will periodically update the list of drivers as new ones become available.

Printing can be accomplished by either direct connecting a printer via the rear USB port or connecting the printer to a network. 

Print Function in Essentials searches for all connected printers and displays a list to be selected.

Question:

We have target values for LAB (C/2) and YI D1925 for our product and need to now specify LAB (C/2) and YI-E313 (C/2) targets.

Answer:

The CIELAB targets would stay constant.

Note in the equations below that the terms A,B,G do not correspond with CIELAB, they are quantities defined in ASTM E313 and the the terms XYZ are the observer weighting functions. YI-E313 ignores the red X contribution of color in the index calculation.

YI-D1925 = 100(A-B)/G = 100(1.28X-1.06Z)/Y

YI-E313 = 100 ( 1 - B/G) = 100( 1- ((Z/1.181)/Y))

You would need to run a MonteCarlo simulation to determine the YI-E313 range of acceptance using the bounds of the LAB acceptance.

We can do this for them if they provide a PO for 2 hours of Technical Support time.

The attached customer data sheet is required to begin a service request for your instrument. The Customer Experience team will need this sheet filled out in its entirety before they can issue a service return order (SRO) number. 

Question:  Is dE the Standard Deviation between Sample and Standard?

Answer:

A bare bones description might be;  dE is color difference from a Standard and when a tolerance is applied, it is presumed than any dE value less than the tolerance will be an acceptable match.  CIE76, which is the technical description for dE*, is the geometric distance in color space between the Standard and Sample reading.   Since human perception is not uniform throughout the gamut of color space it is recommended that each Standard Color have a unique acceptance tolerance associated with it when using dE*.    For example our ability to differentiate between different shades of Yellow is much greater than our ability to differentiate between shades of Deep Blue.  If a tolerance dE* < 1 indicates an acceptable match for the Yellows, to have a visually comparable tolerance for Deep Blue might result in a dE* < 1.7   

CMC (dECMC) and CIE2000 (dE*2000) consist of complex equations such that a uniform tolerance can be applied throughout color space.   These equations were designed so that a value of 1 represents the limit of an typical acceptable match.   Using CMC or CIE2000 would allow the user to apply a tolerance of 1 to both the Yellow and Deep Blue colors from the previous example.     

Standard Deviation, and k or C.I. (confidence interval),  are statistical terms that are used to model univariate groups of data that follow a Gaussian distribution.   These models work well when applied to XYZ or  Indices, but may be flawed when applied to multi-variate values like the different dE types.  Since dE can't be negative it's impossible to get a normal distribution, which is what Std. Dev. is designed to represent.   When using a group of dE's a Hotelling model t2 should be used.

Handling, Care and Cleaning of Instrument Standard.

The White Standard is an optical coating and should be handled in much the same way as other optical surfaces. Although the material is very durable, care should be taken to prevent contaminants such as finger oils from contacting the material’s surface.  If the surface appears lightly soiled, it may be air brushed with a jet of clean dry air.  For heavier soil, the material can be cleaned by scrubbing with a soft brush under running water. Blow dry with clean air or allow the material to air dry. If the material is heavily stained, soak with either an extremely mild mix of soap and water, 5% white distilled vinegar, or hydrogen peroxide. Then run under water while scrubbing with a soft brush. Always keep tiles in the Standards box when not in use.

HunterLab follows the recommendations set forth by ASTM E1164.

Referring to section 10.2.1 which states that the Full Scale Standardization shall be done using a White Reference Standard calibrated relative to the perfect Reflecting diffuser. This implies that the White Instrument Standard has unique calibrated values which would be substantiated by a Calibration and Traceability statement.

Referring to section 10.2.2.1 for 0:45 and 45:0 Zero Scale Standardization shall be done with "a highly polished black glass standard with an assigned reflectance factor of zero." This implies that for any highly polished black glass the reflectance factor is zero at all measured wavelengths. There is no calibration required to assign the reflectance factor at each wavelength. The reason why no calibration is required is that except for a few very expensive instruments maintained by the NMI's of the world the true reflectance of polished black glass is many magnitudes below a commercial instruments ability to measure it.

Some customers have reported that Essentials-based instrument freezes and could not boot up successfully.

First, makes sure that the microSD card is properly seated in the card socket.  Power system down and remove and replace microSD card.  Re-apply power.  If it still does not work, please check the following steps.

If instrument can boot up correctly with a SD card inside before, it means that the SD card gets corrupted by some reasons, like Vista is shut down suddenly when the system still have something running. Please contact support@hunterlab.com, provide us your Vista serial number and ship back the corrupted SD card to us. We can help you to recover the data from the corrupted SD card in our office and then send you a new SD card with the recovered data. We can also email you the recovered data, and then you can import all recovered jobs by Job menu/Data Management/Job/Import, or simply apply restore (Job menu/Data Management/Backup & Restore) to replace current Hunterlab folder in your new SD card with the recovered one.  

If Instrument has never boot up successfully with the SD card inside before and shows "Bootscript not found" error, you probably have a wrong SD card version. Please contact support@hunterlab.com and provide your Vista serial number. We will send you the right version SD card. 

Instrument standardization where the Bottom of Scale (0% line) and Top of Scale (100% line) is set by first blocking the light path and taking a reading and then clearing the light, except for a blank solution and taking a reading. This must be done at least once for every 8 hours of use, or at any user selectable interval less than 8 hours.

Instrument calibration can only be done by trained HunterLab service technicians at our Reston, VA service center. This entails using the emmission lines of Hg and Kr or lasers such as HeNe or CdNe to set the wavelength mapping of the detector and then ND filter and Gray scale tiles to check the Linearity and then colored filters and tiles to check the color measurement accuracy of the instrument. Instrument calibration verification testing is recommended every 12 to 15 months. If any test produces a failure then returning the instrument to HunterLab for calibration is the required action.