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