Why Colour Quality Management in Packaging is Essential?

The benefits of colour quality management in packaging are too numerous to cover here, but here are the top 6 essential reasons to help you.

1. Maintaining consistency of colour is about supply of your ink and substrate, not just colour management

If your customer or the print buyer is a big brand chances are that they have specified the colour and tolerances. This will be provided in the form of L*a*b* values, ΔE tolerances (deltaE) and specifications about the measurement, etc.

First you will need to check that the substrate from your supplier is consistent for finish and colour - within tolerance. And second, importantly, check that the colour of ink from your ink supplier is within the tolerance specified.

How to do this?

a) Have the substrate supplier provide you with thickness, gloss and L*a*b* values or you may need to create a substrate standard yourself. You will need a micro meter, gloss meter and spectrophotometer to do this. Set up a procedure to measure, check and record each batch and/or delivery of substrate supply. This way you can check if it is within tolerance×.

Set up a procedure to measure, check and record the L*a*b* of the substrate each time it is used on press# – #<important> do this after the substrate has been run ‘through’ the press.

b) Have the ink supplier create ink draw-downs on the actual substrate to be used for the printed product. This will go a long way to determining that the ink supplied will be within colour tolerance× required by your customer.

×Tolerance - what tolerance is acceptable? This should be determined and agreed by all parties involved in order to be acceptable for the manufacturing and print process used. E.g. For the substrate it could be L±3, a±2, b±2, for ink spot ones it could be Δ2 (ΔE00).

c) Use a Spectrophotometer to measure and check the colour of the substrate and ink colour. We recommend this be done in conjunction with an analysis and reporting software application.

d) Measure, check and report during the print run at regular (timed or number of impressions) intervals to ensure colour is within tolerance. This is especially important if a new can of ink is used, for example.

Following the above will enable you to maintain control over colour variations that could otherwise lead to expensive reprints and materials wastage.

2. Press Maintenance – regular intervals and track consumables

In order to maintain printer colour management, consistency and repeatability keeping up with scheduled in-house press maintenance is non-negotiable. This may also be combined with periodical heavy maintenance by the press manufacturer or supplier.

This may also include;

a) Procedures and records of ANY maintenance.

b) Using a torque wrench to tighten blankets.

c) Keeping a record of blanket and packing changes.

d) Resetting rollers and strip tests – when and how often?

e) Recording and tracking pH, conductivity, temperatures, etc.

f) Using ISO 3664:2009 tubes in the press console and changing the tubes at manufacturers recommended intervals.

3. Measure and record colour across shifts, presses and sites

How can you maintain colour between each shifts, different presses and multiple sites?

a) Be consistent with the measurement device, target and tolerances – Use a spectrophotometer, the same type, model, etc. Always use the same customer approved colour specification and tolerances.

b) Point ‘a’ is especially important across each shift, each press and each site – this can take time with implementation and training, but in the long term it puts everyone on the same ‘page’.

c) Use colour analysis and reporting software, together with analytics, to enable printer colour management job colour quality reports, trending of colour, tracking of site colour performance. This will provide internal quality departments and customers with the relevant information of how well presses, jobs and sites are performing.

4. Measure colour the right way – digital colour management

We already mentioned in point one (1) that to measure colour you need to use a spectrophotometer – Why? A spectrophotometer enables measurement of spectral data of the colour, which is used to convert to L*a*b*. A densitometer CANNOT do this – a densitometer is a colour-blind instrument. A densitometer measures the ink film thickness, the darkness of the colour, the DENSITY.

A spectrophotometer will enable checking of specification and tolerance – digital colour management the right way. It will also help with whether you need to add extender to the ink, adjust pH or use a new can of ink, etc.

5. You cannot control what you do not measure

Production engineers say of any manufacturing process, “If you can measure it, you can control it, and if you can control it you can reproduce it”!

6. Use a Colour Quality Management system

Across the production process combined with the support process. SOP’s (standard operating procedures), measurement, training and records. A systematic and team approach to colour quality and process improvement.

This can take a little bit of time to set up and can dove tail into existing QMS like 9001. But it removes the ambiguity and provides all staff and departments with a clear set of goals, definitions, responsibilities, improved communication internally and improved communication with your customers.

Key Points

• Maintain consistency of your ink and substrate through standardisation, measurement, specification, tolerances - not just colour management
• Press Maintenance – regular & scheduled intervals, keep records and track consumables
• Measure and record colour across shifts, presses and sites to enable reporting, analysis, trending and tracking of colour quality
• Use a spectrophotometer to ensure accurate measure
• You cannot control what you do not measure
• Use a Colour Quality Management system for a systematic and team approach to quality and process improvement

About the Author – David Crowther, Colour & Print consultant dealing with, colour spectrophotometers, icc profiling services, amongst many other services and products. You can reach him at info@colourgraphicservices.com

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The Colour of your Ink can influence your Printed Results

CMYK or process colour printing should be as easy as pie, because if you are using straight process colours the variables are greatly reduced - right? Wrong!

There is no such thing as a standard CYAN. You cannot go down to your local standards office, open the big safe and find a tin of standard Cyan inside.

Valuable production time can be lost due to the colour of ink the just not being right or not suited to job at hand. Other things can combine with this, such as, substrate type and using the correct colour measurement instrument and settings.

Let’s have a look at the key points to check in the press room.

Check the Ink

For process inks, especially if you are printing offset sheet fed or heat set web to ISO 12647-2:2013 your inks should meet ISO 2846-1:2017, as a start. This is a normative reference in 12647-2.

For special colour inks a draw down sample from your ink supplier is a good place to start. Even better if this is done on the substrate you will print with.

The draw down can then be measured and the spectral data incorporated into your colour analysis and reporting software (e.g. Mellow Colour Print Spec or Ink Spec) as an in-house standard. If the draw down is supposed to match a ‘library’ colour you can use the in-house measurement data for reporting through your internal quality dept and for improving the match through further discussion with the ink supplier.

Either of the above is really required otherwise you will be flying blind, so to speak.

Check you are using the right instrument

You should be using a spectrophotometer with 0/45 or 45/0 illumination. This is the standard geometry instrument that suits most printing and packaging applications. Some highly glossy flexible materials, metallic inks and gold or silver foils may require a spherical spectrophotometer.

These types of materials will not measure the same way that we see that colour when using a 0/45 or 45/0 instrument. A spherical spectrophotometer can be set up exclude or include the gloss component - excluding the gloss can provide an improved visual colour match depending on the material being measured.

See the sample diagram below.

Check your instrument measurement settings

Make sure you are using the same, and correct, settings for the illumination and observer according to the standard. Most colour standards will specify D50/2 degrees - some brands and paper manufacturers may use D65/10 degrees. Check you are using the same illuminant and observer as specified.

Check your measurement mode

This is like choosing a filter setting in your spectrophotometer. The latest ISO 12647-2:2013 specifies M1 mode, to adjust and allow for the increased use of optical brighteners in substrates today. You may have been or are currently using M0 mode which is the older ‘legacy’ setting for most older instruments.

Check what is specified in the standard. Changing to M1 can mean a lot of re-measuring standards etc. But it is worth it in the long run. Other modes are M2 (UV cut) and M3 (Pol filter).

Check your Backing

When you measure a thin or slightly transparent substrate you should always use the correctly specified backing material, underneath the substrate to be measured.

Black backing ensures there will be no influence of what is underneath the sample or printed on the other side. White backing is the standard for measuring digital proofs.

If you print flexo, and / or just print on one side, white backing will be fine. And, there are ISO standards for backing.

Check your dE (delta E) setting

What dE tolerance method should you be using? What is specified in the standard? ISO 12647-2:2013 uses CIELAB dE or dE 76. Many print buyers and brands are specifying dE 2000. Make sure you are using the correct dE according to your job and standard.

Check your measurement and reporting procedures

Measurement of printed samples and reporting should have a clearly defined step by step procedure. This will Measurement of printed samples help avoid mis-reads of samples and strange report results appearing randomly. A procedure or set of procedures should be available to all who are responsible in the colour workflow. These are sometimes called standard operating procedures (SOP’s). A set of SOP’s also enables new staff to be trained correctly and effectively.

Check the measurement data source

Target L*a*b* values should be created from spectral measurement data. L*a*b* values require reference information, such as;

a) illuminant and observer (e.g. D50/2 degrees)
b) Type and Specification of Backing (White or Black)
c) Measurement Mode (M0, M1, M2 or M3)
d) Instrument Geometry, Instrument manufacturer, model, etc.
e) Instrument certification (up to date?)
f) Instrument aperture size (2mm, 3mm or ?)

Straight L*a*b* values with no reference data will have no meaning and cannot be used to accurately communicate colour.

As you can see not all colour measurement is equal. Care and attention needs to be taken when measuring standards and samples!

For more information about the benefits of using a Colour Spectrophotometer training and the TECHKON instrument range please contact us at info@colourgraphicservices.com

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Controlling the Colour Variables in your Workflow - Lighting

We often get asked about how to control colour in the workflow.

Everyone’s workflow is different - digital photo print output, digital production print, wide format display and signage print, commercial offset print, packaging and label flexo print, are just a few of the different workflows we encounter and support in our working day.

Whatever your workflow, in order to maintain predictable, consistent colour quality in print does require that you follow some basic rules. This will help you remove and/or reduce the variables within acceptable tolerances.

One of the easiest things to fix is to have controlled and standardised lighting for viewing and assessing your photo prints, proofs or printed results. Colour management is based on D50 lighting, for measurement and for viewing/lighting conditions.

This is not just someones idea - it is an international standard - ISO 3664:2009. This does require investment in a ‘viewing system’ but it is money well spent.

A viewing system that meets ISO 3664 will remove the ambiguity when visually assessing and analysing printed results.

If you are comparing your ‘prints’ to the same image on your monitor (in PhotoShop or Acrobat for example) you will require a calibrated monitor and a standardised viewing system.

This will confirm your soft proof (image on the monitor) is accurate to the print. 

Attention should be given to the type and quality of the monitor, how the monitor is calibrated, monitor surrounds (wall colour, etc), using a monitor hood and the ambient lighting. Softproofing is worthy of a complete article and can be a lengthy discussion, so we will cover that in another story or blog.

ISO 3664 does provide guidelines for ambient light - i.e. up to around 500 lux, but still with D50. D50 is not just about 5000K tubes or bulbs. The colour temperature is just part of it. It is the spectral quality of the lighting that is important.

D50 ambient lighting is entirely possible by way of LED lighting, tubes and bulbs. If your ambient lighting in your work place is varied with windows, halogen down lights, office warm white ‘fluros’, brightly coloured walls and furnishings around the monitor(s) you will need to eliminate or change some these.

For example D50 ‘fluro’ tubes are available to fit standard size ceiling fluro fixtures. D50 LED tubes are also now available and provide greater longevity and massive savings in running costs.

What are the basic recommendations?

• Use D50 lighting for assessing colour in printed results
• Take control of your ambient lighting and surrounds
• Use a good quality monitor* - calibrate the monitor and use a monitor hood

*with monitors we always say you only get what you pay for!

Want to learn more? 

Contact us at info@colourgraphicservices.com for colour management training and complete colour management solutions.

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