This is a question I get asked very often. First, let’s point out that we are talking about offset here, as digital, wide format and flexo really require their own topic of discussion.

Let’s break it down into what could be the cause and what to check.

1. What is the colour target?
   -Is it an inhouse colour target/standard or international standard or customer supplied target?
   -Check to make sure that your selected target or standard contains the same components (substrate, inks, sequence, coating, etc.)
   -Does the target have the correct instrument settings?
   The colour target should include all of the information, in detail, outlined above.
   e.g. Basically…
   -Substrate type, finish, coating, weight, Lab* values
   -Measurement conditions (M0, M1, M2 or M3) and backing (white or black) and instrument type, geometry
   -Solid CMYK Lab* and Overprints RGB Lab* and dE tolerances (and dE methodology)
   -Calibration method used – CMYK TVI target and spot colour SCTV or G7 calibration
   -Measurement made through coating/varnish?
   
   
2. Check the substrate (paper)…
   -The substrate you are using – is it exactly same as specified in the target?
   -Is the substrate the same type from the same supplier?
   -Is there consistency and QC in the substrate from the supplier?
   -With spot colours are the targets made from draw downs on the same substrate?
   
   
3. The effect of an in-line coating…
   -If there a coating or varnish being applied, in line, on press it will have a large effect on the final results visually and with the measurements.
   A coating or varnish will change the white point of the substrate, usually to a lower L* value and significantly alter the dot gain (visual appearance of tones) by increasing the ‘weight’ of tonal colour appearance.
   -Sometimes the varnish is not applied to the colour bar on the sheet – but the target and measurements here are very important for machine colour process control.
   -With the coating/varnish covering the majority of the ‘product’ area of the job the ‘contract proof’ should also reflect this.
   i.e. The colour and the target of the ‘proof’ should include or simulate the colour as per the final production process.
   
   
4. Are the inks correct?
   -Check with your ink supplier that the inks you are using are correct, as specified – for process and spot.
   -If you are formulating inks internally do you have a procedure to receive a colour quality report that the ink is correct and within tolerance?
   Ideally inks should be measured and checked before going onto press – especially for spot colours.
   
   
5. Ideally inks should be measured and checked before going onto press – especially for spot colours.
   -Thorough press clean-up is required when changing colours on press – if this is rushed and the necessary steps are missed it can lead to contamination
   -Often overlooked – Opacity – this can be measured, for example with a Techkon SpectroDens Premium. This will ensure consistency and the correct print capabilities can be communicated between the printer and the print buyer/customer.
   
   

The above five points outlined should be documented as SOP (standard operating procedures) to ensure press operators, off siders, production and press maintenance personnel are all following the same procedures as communicated to all relevant staff.

We specialize in on site colour print technical consulting, support, and training – To find out more about printer calibration and using a colour spectrophotometer please contact us via our contact form

Print service providers (PSP’s) and brand managers should be in control of their colour quality in print utilizing suitable quality control software. A QC software solution, paired with a suitable Spectro densitometer is now a prerequisite in today’s fast paced, results driven print environment. Samples, colour standards, production jobs can be quickly measured for PASS/FAIL assessment for press operators and production managers. Additionally, the software will provide instruction to quickly attain the targeted result within the required tolerances. Summary and detailed PDF reporting of the job colour metrics can be made available to in house management, the quality department and externally to buyers and brand managers. The quality software package can be used press side or close by in a production or quality area and should be suitable to the production equipment and machines used.

The goal shall be to ensure process and spots fall within the required delta E tolerances, by assisting the operator with the remedial action to take.

Make ready time is greatly reduced and with measurements taken during production a final production report can be produced showing that the colour quality is within the expectations of the customer and meets the company’s quality policy.

The modules within the MC suite of software enables PSP’s, especially in packaging (carton, flexible, etc.) and labels, to measure, analyze, correct and report. The PrintSpec (PS) module is for the CMYK process for ISO standards and G7.

The Ink Spec module is a complete CM system for systematic and measurable control of brand and specials.

InkSpec

What the key rewards with InkSpec?

• Spot and brand colour control and certification system
• Match brand samples across many different substrates
• Print performance is standardized
• Complete management of your customers spot and brand colours
• Internal and external communication is improved
• Downtime and materials wastage is reduced

In packaging time to market is critical – speed and quality of production can regulate SKU (stock keeping unit) success. Reproduction of brand and spot colours with extreme accuracy is becoming de rigueur.

InkSpec provides flexibility to create standards from draw downs, previously produced samples or downloading and importing customer standards from CXF. MellowCloud server allows downloads from your customer – you can even enter the target L*a*b* and TVI values manually. The substrate can also be measured and stored.

The InkSpec database is able to store an unlimited number of samples.

Spectrophotometers from Techkon, X-Rite, Konica Minolta and others are supported. Measurement can be made by spot or scanning small patches within the job. The subsequent readings provide a summary report as well as a detailed multi page PDF report. The details of each sample measurement is clearly shown – how close with pass or fail for each ink.

A report can be produced with or without substrate measurement, solid patches only or solid and tone value patches of your choice. You also have the possibility to see how the hue changes under different lighting conditions. Density target information is also shown to aid the printers.

Sometimes the substrate specified by the customer will not allow the colour to be produced within tolerance, thus requiring a new formulation of the ink. InkSpec is able to export popular formats used by ink formulation systems to enable new and correct formulated ink.

InkSpec for spot and brand colours works with complete synergy with PSpec for CMYK control and reporting. Whatever the mix or process and spots InkSpec and PSpec are the go-to tools for QC and QA.

To find out more about printer colour management matched with a precise Techkon Spectro densitometer please contact us via our contact form

Print technology has come along in leaps and bounds recently whether it be for the home, office, commercial, packaging or labels. As with all gains in technology it is simple to think that the accuracy of colour in print has also improved to the point that we can click and forget – it will be exactly as we see it, no need to worry!
Sure, we now all too often use our smart phone cameras to capture every moment and situation – it looks great on the phone screen – how hard can it be to reproduce that in print, with accurate colour? Well, there is going to be some translation involved as your image moves from capture to display to output. Importantly these are all different devices that each have individual colour behavior. So, how can we maintain our vision of that captured photo to final output or ink on paper? Increasing our knowledge of colour management (CM) can enable us to control the process and trouble shoot.

The TOP 5 THINGS to keep in mind with Managing Colour

1. With printing your image (or document) there are multiple output engines in the reproduction chain. Pictures captured digitally require ‘translation’ (rendering) of the contained data on each device – camera, display and printer. As stated above each of these handles that data differently – i.e. is it RGB or CMYK? Is it for input or output? What is the flow here?
   Photo(s) taken with the ‘camera’, translated to the display on the camera or phone screen, copied to a computer, opened in image editing software, placed into a production document (think InDesign file), exported as a PDF and then to a production process for ink on paper. Of course, you could simplify that by just outputting a photo but usually it will still go from camera to computer (and display) to output device.
   You want the final result to match the photo from your camera, right? Theoretically possible* with the correct ‘adjustments’ as the captured data is passed from device to device. *We say theoretically as there are limitations to the colour capability of each.
   
   
2. Reproduction of colour is a combination of a system and craft
   Let’s think about colour – without light there is no colour. We print with Cyan, Magenta, Yellow and Black – Light reflects onto paper (or the substrate) and some of the light is absorbed (or subtracted) by the combination of Cyan, Magenta, Yellow and Black and what results is we see the reflected colour. A phone, tablet or computer display (monitor and/or TV) is a RGB (Red, Green and Blue). It starts off black or blank and different amounts of RGB are added to show us an image on the display. The digital image on the display is built up from RGB pixels. RGB is additive colour and CMYK is subtractive – they are complete opposites. RGB devices are screens or displays, as well digital cameras and scanners. An output machine for ink on paper is usually CMYK, that can be blended and controlled.
   For printing, when a photo is captured from a camera the RGB data is converted to CMYK data that the print engine can understand. The translation can yield horrible, unwanted colour if certain rules are not followed and adhered to. The key here is to realize that RGB devices have far greater or larger colour capabilities than CMYK. Some colours captured digitally in RGB and displayed on a monitor will not be able to be produced with complete accuracy in Cyan, Magenta, Yellow and Black – there is a limitation to what the Cyan, Magenta, Yellow and Black process can reproduce. However, using the correct CM technique it is possible to output the best achievable Cyan, Magenta, Yellow and Black result from any RGB combination
   
   .
   
   
3. Translation from digital capture to a print space
   Printing can still be considered a craft, but you can also argue that it is a service as printing companies are now seen as PSP’s (print service providers) and no longer considered to be manufacturers. However, at any level printing still necessitates technical human competence, proficiency and skill. When moving from digital to actual ink on paper there is quite a bit going on. There is liquid ink made up from pigments and other chemicals or maybe toner powders – either way there is an interaction between the ink and paper (or substrate). Paper itself varies hugely from uncoated bond you might have in your home or office output, to gloss, photo, fine art papers – the list is endless. The way the ink is laid down onto the paper causes a variety of results in the way they connect with each.
   – Yes, it can be fairly easy to produce ink on paper, but to do it with predictability, accuracy and consistency requires some extra procedures.
   
   
4. Image resolution and print quality
   Image resolution is described as DPI (Dots Per Inch) – this will not change when you send it to output as ink on paper – the original image will always be 300 DPI. A photo or picture at 300 DPI means there is 300 pixels per inch. Digital production machines can output at various resolutions also described as DPI. But the key point here is the print resolution or DPI is controlling the machine behavior – higher DPI output will be slower and should produce more detail in the final result – only if there is more detail that can be extracted from the photo. E.g. A 72 DPI photo will not look any better produced at 1200 DPI compared to being produced at 300 DPI. There not enough resolution and detail in the original photo at 72 DPI to show any improvement when outputting at a higher resolution. For high quality photographs, it is best to make sure the image is at least 300 DPI at the final size you to produce at. i.e. You have an 8” x 10” photo with a resolution of 300 DPI – you can output this at the same size (8” x 10”) or smaller (4” x 5”) without a problem. However, if you wish to output it at 16” x 20” you will be ‘scaling’ the image at 200%, the DPI will drop to 150. This means the detail in the final result will be reduced and it will start to look ‘pixelated’.
   
   
5. High quality ink on paper production is a multi-level process that requires technical human competence, proficiency and skill
   
   All digital print engines behave and output differently – there is a lot of mechanics
   – No one likes to hear it, but every output process has some sort constraints and limits.
   There have been major advancements with digital and wide format over the last 10 years producing huge signage and display production that we never saw before. Textile printing is moving very fast with home furnishings and fashion fabric designs being made with eye catching design and colour detail. At the same time high end graphics displays are able to show finer details and a broader range colour.
   – A key point is that the RGB colour gamut exceeds that of CMYK.

Translate with ICC Profiles

To manage colour effectively from device to device we should use ICC profiles. An ICC profile gives meaning to the photos, files and devices we use – from capture to output. A profile describes the colour capabilities of the device it is associated with. i.e. digital image from a camera, the computer display, inkjet photo output, the offset process, etc. This means an image will look different on each device. Using ICC profiles correctly enables us to view an RGB image on a monitor and simulate (soft proof) how it looks when produced on office laser output, on an inkjet photo machine or even in brochure we are having produced on an offset press. An ICC profile can be attached/embedded to individual images/files (RGB or CMYK) and even PDF’s to describe their final output intent.

Where do I start?

The first step is to calibrate your computer display – this will enable accurate image evaluation and editing. There are plenty of low-cost solutions for monitor calibration that will include a colorimeter or spectrophotometer and calibration/profiling software.

Once your display is calibrated (and profiled) you can then view RGB or CMYK photos with confidence, perform editing, convert from RGB to CMYK and even soft proof your images. Your photo editing software must support ICC profiles to do this.

A computer display will change or drift over time so you will need to check and validate the colour periodically using the calibration hardware/software package. If it falls outside the desired tolerances, you will need to re-calibrate.

Software application set up

As stated above your software* for image editing, vector-based file creation and editing and page/document production all need to accept and be able to work with ICC profiles. This allows for effective CM throughout a design, production workflow. *(could be Photoshop, Illustrator, InDesign, Acrobat from Adobe, but there are other apps you can use as well). A CM workflow requires profiles with a clear description of a source and destination colour space.

Summary

Soft proofing is often a very underutilized tool in the production process. You can gain a lot by accurately soft proofing your images and production PDF’s prior to sending to your type of output production or PSP (service provider). Importantly, please understand that you will achieve a more accurate soft proof with properly calibrated monitor and using the correct CMYK profile. And with monitors you get what you pay for. You should not expect CM miracles from a laptop display, or a cheap computer display compared to a high-end graphics display like an EIZO CG series.

It can seem too daunting and complicated but going through each step in the workflow to set up CM correctly will end up saving you a lot of time and you will avoid disappointment with your final ink on paper result.

To find out more about printer colour calibration and print quality management please contact us via our contact form

As such then, the quick reply to the above is “no”. Many believe that if it still works then there is no termination date on your measurement device. But there are key influences to consider regarding the effectiveness and efficiency of older colour measurement instruments. Think for a minute how the market has evolved and changed over the last 10 years.

• Are you still receiving the full benefit of your older press room densitometer and spectrophotometer?
• Can you easily meet the challenge of completing quick measurements to confirm G7 or ISO 12647?
• Does your existing densitometer or spectrophotometer still have the functionality to enable you satisfy and exceed the current tasks and trails facing your quality and printing department?
• Can you easily generate colour quality reports for internal use and for your customers on request?

The Techkon SpectroDens was a GATF InterTech award winning device in 2018.
When considering this highly esteemed award, the judging panel were mindful of the functionality and failings of many older spectrophotometers and densitometers used in printing depts. Nonetheless, after stringent testing of the SpectroDens, the judging panel commended the exclusive combination of extremely fast measurement speed, enhanced cleverness, and an in-built mode for colour bar and strip scanning. The judge panel concluded by asserting that they anticipate the SpectroDens4 becoming the No. 1 spectrophotometer in many printing depts.

Want to learn and know about why the GATF preferred the Techkon SpectroDens for the InterTech award? Why consider upgrading your older instruments?
We have put together a list of dynamics and elements you should reflect on regarding your existing press and quality dept instruments. Are there benefits added when upgrading to up-to-date, and scientifically advanced spectrophotometer for your quality dept and printing dept? See below…

Why Upgrade to the latest SpectroDens:

• Speed – It will be faster than your existing instrument covering the same functions (density, dot %, ink trap, etc.) in less than a second
• Comfort and Use – SpectroDens utilises a original side aperture which enables the user to quickly position the measurement aperture over the desired measurement area for faster operation and measurement
• Adaptability – Effortlessly change from spot measure to full colour bar scan mode with the simple touch of a button. No need for expensive options or accessories
• Precision – The spectral sensor measures colour in almost 3nm increments – ultra-high definition – providing greater than 3 times the resolution of many existing and old instruments for higher accuracy measurement and control
• Agreement – Techkon uses a calibration standard that connects to NIST (Nation Institute of Standards and Technology) master colour standards and metrology for “plug and play” measurement agreement with other common instruments
• Spot Colours and Expanded Colour Gamut (ECG) – A Spectral Engine is utilised in order to achieve and maintain precise and repeatable density & dot gain measurements of Spot Colours and Expanded Gamut (ECG) process colours. Older densitometers will always struggle to achieve precise and repeatable density & dot gain measurements of Spot Colours and Expanded Gamut (ECG) process colours
• CIE Lab & deltaE – Your customers are increasingly asking for and specifying colour with CIE Lab co-ordinates and print tolerances with deltaE. Only a spectrophotometer can measure and report CIE Lab co-ordinates and the deltaE colour difference from a standard, draw down or multiple production samples
• Direction – How do you achieve the lowest deltaE? The InkCheck function tells the press operator whether to move solid ink densities UP or DOWN and by exactly how much so they can achieve the best possible colour match and lowest deltaE
• G7 – The world’s most successful print certification program. Your customers are asking for and seeking company’s and service providers with Idealliance G7 Master Qualification. You need more than just a densitometer to complete G7 implementation and conformance. A spectrophotometer, ideally the SpectroDens, enables fast and easy G7 set up and control – complete easy to use G7 functionality is included!
• Robustness – The SpectroDens has a one piece machined body with precision from a single “chunk” of aluminium. This maximises durability and reliability in tough and unforgiving production environments like press rooms.
• Battery Life – SpectroDens has a rechargeable LiFePO4 type battery. This provides long use before recharging is required. Additionally, easy inductive charging is used. The device can also charge via the USB cable when connected to a suitable computer.
• ISO Standards – Quick and easy Pass or Fail notification for ISO standard print and all proofing standards
• Wi-Fi – Wireless or ‘wifi’ connection to the host computer, offers. This provides fast communication speed, superior security, and a larger area of connectivity range when compared to devices that utilise use Bluetooth

To find out more about the above or the Techkon SpectroDrive or SpectroPlate please contact us via our contact form

For printers, quality managers, brand managers, prepress – Techkon is always the first they will reach for to complete colour process control and quality assurance.

Colour control and Quality Assurance

Techkon handheld and scanning measurement instruments can show you a pass or fail according to international, in-house or customer standards. Combined with ChromaQA, easy to use, but sophisticated quality assurance solution is able to show printers and quality managers the colour results from production on press as it happens. Alternatively link your Techkon with top of the range Mellow Colour PrintSpec (CMYK), InkSpec (Spot colours) and Impression Proof for cloud based remote colour approval without having to leave your office or do an on-site press check! With Techkon make ready times are reduced, colour consistency and accuracy is improved, re-prints or re-makes are reduced, press utilization is increased all of which brings you significant savings in paper and ink. Colour issues and problems are detected earlier in print production.

Ease of Use and User Experience

Techkon provide instruments that are fast, accurate, and the most comfortable & effective colour measurement tools to use in the pressroom or in prepress. Press operators consistently prefer Techkon to the standard press manufacturers devices they have used previously. Techkon’s close attention to detail in the product design process ensures the best user experience. End user feedback from the field, incorporating real world work environments makes, means Techkon the number one choice where critical colour management is required.

Third Party Connectivity

Techkon believe that their open connectivity approach is in the best interests of their customers and end users. has always believed that an open approach is far better for our customers. With strict adherence to measurement mode standards, it is no coincidence that Techkon measures like those from the largest competitor thus ensuring interchangeably at any point across the print production workflow. Additionally, Techkon instruments connect seamlessly to a vast array of third party colour quality software applications. Techkon’s global network of software development partners is always increasing with commitment to an open approach moving forward.

First Class Service

Techkon and their worldwide partners place the greatest importance on exceptional customer service. Customers require our responsiveness and willingness to help so they can succeed in business. Techkon and their global partners utilise extensive customer, industry and product experience to provide highly personalized advice and guidance through the sales process and anytime you need support.

To realise the full benefits of the TECHKON SpectroDens, SpectroDrive, SpectroPlate and DENS instruments please contact us via our contact form

The short answer is YES! Standards enable everyday life. From paper sizes, think A4, to the building of a modern home that you may live in – two examples of where standards are used and without them either of the aforementioned would not be possible.

Standards in print allow you to justify and account for the operational processes in manufacturing. Standards assist with your methodology in providing your customers with the expected printed product. Utilizing the colour quality standard ISO 12647-2 helps you to maintain customer satisfaction and loyalty and reduces the risk of costly reprints because of poor or out of tolerance colour. Print companies who keep up with the latest standards are building a reputation for quality through accreditation with a recognized standard.

Standards in print allow you to justify and account for the operational processes in manufacturing. Standards assist with your methodology in providing your customers with the expected printed product. Utilizing the colour quality standard ISO 12647-2 helps you to maintain customer satisfaction and loyalty and reduces the risk of costly reprints because of poor or out of tolerance colour. Print companies who keep up with the latest standards are building a reputation for quality through accreditation with a recognized standard.

You are probably aware that standards are constantly being updated, every 5 years or so. This can mean a minor revision to a complete re-write. With the rapid advancement of digital technology there are several changes underway with new ISO standards being developed.

New standards in Print

The best-known standard is ISO 12647-2, the offset colour. The latest release was in Dec 2013 and a review should be complete by next year, 2027.

The values contained in this document are often used as a reference for other print processes and systems.

ISO 19301, 2 and 3 are emerging standards for colour quality management, colour conformity of a printing workflow and packaging printing colour reproduction.

Additional there will be reviews of ISO 15311-1 and 2, which covers measurement methods, reporting schema and print quality requirements. These can used for digital and traditional forms of printed materials.

There is also work under way to enable consistent and objective comparison of the colour gamut of different printing systems.

In a declining industry Packaging is one of the few areas to show slight, but steady increases in overall volume, year on year. A vital and large area of packaging is produced by the Flexo print process. Consistent brand colour is imperative here and with continuous improvements in Flexo print technology the use of spot colours within tonal reproduction is on the rise. Checking for solid or 100% spot colours is well documented. The recently released ISO 20654 specifies the new method required for measuring the calculation of Spot Colour Tone Values (SCTV), which is much more accurate – This differs from the usually used Murray Davies formula used for process colours. This will most likely be used in the next revision of the ISO 12647-6 flexo standard. See the examples of ‘normal’ dot gain measurement Vs SCTV measurement on a ‘RED’ spot colour below.

Having a colour quality management system in place with good procedures, measurement and records requires a cross section of, colour and QMS standards. Many print companies do have limited colour management (CM) policies, they believe in performing printer calibrations and their digital colour CM is looked after by their preferred digital equipment supplier, but this is not enough… It is only a small part of the equation. and in that situation, you are not in control.

How to keep up to date?

To keep up date with new and changing standards, industry requirements and brand owner expectations is not an easy task. The internet of course has made communications and the transfer of knowledge and information much easier, but not always reliable.

There are usually local print industry groups and ISO Technical Committees (TC) who are more than willing to advise, help and listen to your opinion. If you feel that you input is warranted it is definitely worth your while to get in touch.

You can of course stay in touch with me for all the latest in what’s happening with colour standardisation, as I volunteer my time on the local TC130.

For more information about what’s happening with colour standardisation and the benefits of using a Colour Spectrophotometer training and the TECHKON instrument range please contact us via our contact form

Dependable and reliable colour measurement can be affected and influenced by a number of factors, such as, instrument type, instrument settings, backing, optical brightening agents, calibration, environmental conditions and more…

Some of the above can be controlled by software so you will need to check and re-check your configuration. Incorrect settings will directly affect the software you use for collecting, comparing and reporting your colour measurements.

Instrument Type

Spectrophotometers basically come in three types of geometry, 0/45 or 45/0, Sphere and Multi- Angle.
For ‘print’ colour measurement we would be using a 0/45 or 45/0 instrument, which means the light source and measurement are fixed at one of the two aforementioned angles.
Sphere and Multi-Angle instruments are mainly used for ‘industrial’ colour measurement, plastics, architectural coatings, metallic paint, etc.…

If you are comparing and sharing measurements then you should be using the same geometry and instrument type/model, etc.

Settings

Spectrophotometer settings have a direct effect on the final colour measurement values reported. Keep the same settings for consistent measurements and document your settings.

Documented settings might look like:

• 0/45 Geometry (Instrument Geometry)
• D50/2 (Illuminant and Obsever)
• M0 (Measurement mode – M0, M1, M2 or M3)
• 3mm aperture (Measurement aperture size)
• Black Backing (Backing can be white or black)
• dE2000 (Colour difference formula – dE76, dE94, dE2000, dE CMC)
• Absolute White Calibration – Calibration on white reference or substrate?

Papers or Substrates with Optical Brightening Agents (OBA’s) or FWA’s (fluorescent whitening agents)

Much of the paper produced today contains an amount of OBA’s. This chemical compound absorbs light in the UV region which then makes it appearance to our eyes in the blue region of the visible spectrum.

i.e. Paper with OBA’s looks brighter and ‘whiter’ but is actually ‘bluish’ and this is evidenced by spectral measurement and the subsequent ‘lower’ b* value. Fine Art and some special cotton-based inkjet photo papers usually contain no OBA’s and therefore appear more ‘yellowish’ than ‘white’.

– You should use M1 or M2 for papers with OBA’s.

The image on the left is with UV light. The top printed sheet contains a high amount of OBA’s, as can be seen by the way it is ‘fluorescing’.

The colour difference between two solid Yellows, using different dE formulas…

Calibration

Spectrophotometer calibration on the absolute white standard is often underestimated in importance.

Before every series of measurements, a calibration should be carried out. After calibration, most devices, are stable for a long term, but we would always recommend performing calibration before starting a new series of measurements to ensure the device is working properly.

And, very important:

• Make sure the calibration plaque (white tile) is clean
• Make sure the plaque is not damaged or marked
• Use the plaque ‘matched’ to the device (same serial number)

If the plaque is not clean or marked it will introduce incorrect measurements or errors. The plaque serves as a reference, so the device then knows what ‘white’ actually is. Using a plaque from another device may allow the device to ‘calibrate’, but this will still introduce measurement errors…

Certification

Is the instrument certification up to date? Handheld and bench top spectrophotometers are precision instruments, manufactured to tight tolerances. Proper use, care and maintenance of your device will provide with you long term stable results, but they can change or drift over time and even become damaged in way that is not obvious to us.

Instruments should be periodically checked and re-certified by the manufacturer to ensure operation within specification. Some manufacturers recommend re-certification every 24 months, others every 12 months.

Setting up an in-house validation procedure for your instrument(s) is also beneficial as it allows you to track instrument performance over time, and can alert you to instrument problems and ‘drift’…

Environmental considerations

Spectrophotometers are often used in varied and diverse environments – Office conditions, production areas, laboratory or quality departments, next to or on manufacturing equipment, etc. But they are still precision instruments and do not like extremes in temperatures or being dropped. Dust, dirt and other contaminants are enemies of spectrophotometers – dirt or dust on the optics can really affect the measurements. Take care to ensure your instruments optics are kept clean – dry compressed air is good to clean dust/dirt from external optics, external glass and the casing.

Spectrophotometers are often used in varied and diverse environments – Office conditions, production areas, laboratory or quality departments, next to or on manufacturing equipment, etc. But they are still precision instruments and do not like extremes in temperatures or being dropped. Dust, dirt and other contaminants are enemies of spectrophotometers – dirt or dust on the optics can really affect the measurements. Take care to ensure your instruments optics are kept clean – dry compressed air is good to clean dust/dirt from external optics, external glass and the casing.

To get dependable measurement you should pay close attention to;

• Measurement settings – including backing
• Instrument calibration procedures – including checking the white tile
• Certification, is it up to date? And in-house validation procedure
• Where is the instrument used? – consistent room temperature, dust and dirt

For more information about the benefits of using a Colour Spectrophotometer training and the Printer Colour Calibration please contact us via our contact form

D
ensitometer and Spectrophotometer – What is the difference?

These are the two colour measurement instruments we get asked the most about. Each has their place, and purpose, so in order to decide which is appropriate it is essential that we delve into each devices characteristics, details and functionality.



1. Densitometers

Densitometers traditionally come up with a density ‘figure’ when measuring a solid patch of colour, usually Cyan or Magenta or Yellow or Black (print process colours). Printers will recognise densities like 1.45 for Cyan and Magenta, 1.05 for Yellow and 1.7 for Black, based on ISO or ANSI Status T.



A densitometer uses a filter that is complimentary to the colour being measured.

Cyan -> Red filter

Magenta -> Green filter
Yellow -> Blue filter



As such we can describe a densitometer as a colour-blind instrument. Simply put the filter makes the colour appear a shade of black and density is based on a logarithmic calculation. i.e. Density = Log₁₀ (remission).
Remission is a measurement of reflected light, which means 1.0 is perfectly reflective and 0.0 is perfectly absorbent. Using the equation above, a grey patch that has a remission of 0.50 (or 50% reflection), would yield a density of 0.30 D.



This makes a densitometer great for determining ink film thickness (density) and when used correctly will easily pick up large, and subtle, variations in density that the human eye cannot detect.

A densitometer easily becomes the printer’s friend as they can also provide additional measurement data for;

• Dot Area
• Ink Trapping
• Dot Gain
• Print Contrast
• Slur and Doubling

  

It is important to understand that a densitometer does NOT measure the actual half tone dots – it measures the density or tone value. Mathematics is then used for dot area and dot gain calculations.


Monitoring tone reproduction quality is especially important across all print processes, offset, flexo and digital. Just getting the solid densities in tolerance does not guarantee good quality colour reproduction.



Some densitometers are capable of measuring according to one status type.
Therefore, it is important to know what density status you are using and to always identify that when communicating or reporting density measurement values.

As a guide:

1. Status T, with no polarisation filter is commonly used in the USA
2. Status E, with polarisation filter is used throughout Europe
3. Status A, M and I may be used in other applications like photographic

2. Spectrophotometers

A spectrophotometer is a complex precision instrument and therefore will always cost more than a densitometer.



A Spectrophotometer typically captures a colour sample from across the visible spectrum (400 ~ 700 nanometres) and provides a spectral data curve or spectral ‘fingerprint’. With spectral data you are able to qualify paper and ink. Is the ink supplied within the required tolerance? i.e. A spectrophotometer can tell you if your CMYK ink set can print within ISO 12647-2 tolerances. Or if the spot colour is within dE (delta E) tolerance to match the required brand colour?



The spectral data is usually converted to metrics to describe the colour, such as LCh* (Lightness, Chroma and Hue) or Lab*. These metrics closely resemble how we perceive colour.

There are different types of spectrophotometers used in industrial applications, like automotive paints, architectural finishes and coatings, paint formulation and finishes, ink formulation and finishes, plastics and, in print areas, for paper and substrate manufacture, ink and colourant formulation, proofing calibration and verification, press room colour control and print QC/QA.

Spectrophotometers are also commonly used in colour management across image capture (think colour scanners and digital cameras), displays (colour monitors), inkjet, digital and wide format printers for CMYK or RGB output, in fact anywhere in print where colour measurement and colour reporting is required.

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We are going to look at choosing a spectrophotometer for use within printing – covering offset, flexo, digital and wide format print. In these areas the substrate can be paper, carton material (board), flexible packaging material (plastics, polypropylene, etc.) and in the wide format area flexible (i.e. self-adhesive, banner, etc.) or rigid material (screen board, core flute, foam core, etc.)

When deciding which spectrophotometer is right for you there are a number of things to consider.

1. What sort of substrates are going to be measured?
   
   For ink on paper, sheet-fed offset, heat-set web offset, digital production print and digital proofs, using fairly standard thickness stocks (up to around 400 gsm) a bench top automated chart reading (Bench top) spectrophotometer may seem to be the right choice here. But there is another couple of areas to consider as well, which we will cover in the next steps.
   
   If you need to measure rigid type materials, such as “core flute”, foam core, screen board, plastic sheeting”, amongst others, a handheld instrument might seem like your only choice. But there are Bench top spectrophotometers that can measure substrates up to 20mm thick, according to manufacturer’s specifications. These instruments also offer the ability to measure transparent media, such as ‘backlit’ material.
   
   What if you need to measure flexible packaging material, like a thin ‘polypro’ used in flexo printing. You may be able to use either type of spectrophotometer here, but you will need to consider the use of a standard ‘backing’ (white or black) because of the colour show through with this type of substrate.
2. How will you use your Spectrophotometer?
   
   Will you be measuring charts for ICC profile colour management? Will you additionally need to spot measure or scan ‘patches’ of colour for QC and QA? Do you need your spectrophotometer to work with third party colour management software? Do you require portability? – i.e. taking a handheld to different areas/depts on site or even to other sites?
   
   How you wish to use your spectrophotometer may well be the determining factor here…
3. Are the ‘instruments’ going be part of a ‘workgroup’?
   
   Will all the usage of your instruments be centralized? Or will there be a number of instruments from across various sites that require correlation with measurement accuracy?
   
   If say, you are going to use three spectrophotometers across three sites then you should consider using the same type, model and specification. Not only are you dealing with one instrument repeatability, but you are also have to think about the tolerances of each instrument.
4. Does the instrument conform to ISO 13655:2009 for measurement modes M0, M1, M2, M3?
   
   This is important for ‘print’ measurements as quite often the substrate contains an amount of optical brightening agents (OBA’s). Many spectrophotometers available now can use the measurement conditions M0, M1, M2, M3.
   
   Many older spectrophotometers only used M0 – an incandescent lamp with relative spectral power close to CIE standard illuminant A.
   
   M1 aids in minimizing measurement differences between instruments due to OBA’s and fluorescence, by matching CIE illuminant D50. ISO 3664:2009 specifies D50 as the standard viewing condition for print, graphic arts and photography.
   
   M2 is similar to the previous usage of a UV Cut filter – to exclude differences in measurement due to fluorescence of OBA’s in the substrate.
   
   M3 is essentially the same as M2, but includes a polarising filter to remove and or minimize reflections – also differences between wet and dry inks (dry back).
5. Do you require your spectrophotometer to measure according to standards?
   
   The ISO 12647-2:2013 standard states that measurements “should be made using M1”. Therefore if you are using 12647-2:2013, or a later amendment, you should be using M1 mode, with white or black backing.
   If you are going to use an in house standard or something specified by your customer or brand owner then this should be clearly communicated stating the illuminant, observer, geometry, backing and /or alternate mode. i.e. M2.
6. What is your budget?
   
   I leave this obvious point to last – not that the above points are in any particular order. Price is always going to be a consideration – but the quality of a spectrophotometer will be remembered long after price is forgotten. You need to be realistic here as these are precision instruments that require care and looking after. You should have your spectrophotometer(s) checked, serviced and re-certified by a reputable instrument laboratory or the manufacturer at an interval according to the manufacturer or set by your quality management system policy. Either way it is best practice to have an in-house validation procedure in place, together with records.
   
   So, which spectrophotometer to choose – handheld or bench top?
   Your choice can be narrowed down depending on how your answer the previous 6 points.

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P
rinter calibration is required for any print device in order to get it into a stable, repeatable state.

Let’s break it down into what could be This is necessary as it enables you to bring the printer back in line, so to speak, as it will drift over time.the cause and what to check.

Basically, once you have the calibration process down pat you will be able to produce predictable, accurate and repeatable colour.

The idea is that if your colour starts to move away, out of tolerance, a quick check of the calibration, re-calibration or adjustment of the calibration will bring the colour back into ‘line’, without the need for complete re-profiling, etc…



For the wide format market, covering display, signage and the like, I am not going to be specific about the substrate or media, printer type, ink set and TIP type in use. There so many combinations it would take more than a month of blogs or more to cover…



Good colour management strategy dictates that you should always calibrate your device first before creating your ICC profile.

This is colour management 101!

Calibration – the process of bringing a colour device (i.e. monitor or display, printer, and even a scanner…) into an optimal, quantifiable, repeatable state. This condition could be an industry standard, manufacturers spec or guideline or your own specification.

With wide format printer calibration, the printer will be controlled by a RIP, and the RIP will usually have an in built calibration process prior to creating an ICC profile.

The steps of calibrating the printer will usually follow, but not always, this order:

1. Per channel ink limits
2. Linearisation (tonality)
3. Overprint ink limits
4. Grey Balance
5. Profile creation
6. Profile and colour management validation

Per channel ink limiting is usually the first step. This about achieving ink/media compatibility for each of the inks, per channel, C, M, Y and K. Too much ink being laid down can cause problems such as puddling, ink not drying, and ink reticulation.

To achieve the goal here, you are looking for the optimal result – enough ink without causing problems, together with enough ink to produce enough saturation larger than the target gamut you are aiming to simulate.

This step usually involves visual assessment and may include measurement using a densitometer or spectrophotometer.

This step usually involves visual assessment and may include measurement using a densitometer or spectrophotometer.

Tonality or tone distribution is about achieving smooth and even tone graduation from 0% to 100% for each primary channel C, M, Y and K. This step involves visual assessment and will include measurement using a densitometer or spectrophotometer.



Overprint ink limiting is about looking at the build-up of ink once the primaries (CMYK) are mixed together in different combinations – i.e. 100% M and 100% Y for RED. This step usually has a complex looking chart with rows of ink channel combinations in varying amounts.

This step definitely requires visual assessment.


Similar to per channel ink limiting except you are looking to find the step in each row that can produce the ‘best’ result with showing problems (ink puddling, not drying, etc.). You will probably need to input your results and print again to confirm your settings are correct…



Similar to per channel ink limiting except you are looking to find the step in each row that can produce the ‘best’ result with showing problems (ink puddling, not drying, etc.). You will probably need to input your results and print again to confirm your settings are correct…



I prefer to use a custom chart I have created for this purpose. It also helps you to decide on some important profile settings, such as total ink coverage and black start point. If the output of the calibration chart looks ok you can proceed to creating your ICC media/substrate profile.



Output your preferred CMYK profile chart – I like to use a profile chart with 2000+ patches for accuracy and coverage.

Measuring and building your profile really requires another blog as there are quite few options for measuring and then the settings for building your profile. Suffice to say once this step is complete you should be looking to validate your profile and validate your colour management settings in RIP, using your new media profile.

This does involve critical visual assessment, under the correct lighting (D50 – ISO 3664), and spectral measurement for reporting to see how your output now stacks up compared to an international print standard (ISO 12647) or an in-house standard. Again, I think it best to tackle this subject in a separate blog.

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