Building Color Libraries with your Spectro-Densitometer

  

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Question: With four SpectroDens devices on different flexo presses, running three shifts, how can I set up all the color libraries, get my entire staff trained and be assured they are all following the same prescribed procedures?
Answer:  Build highly accurate color libraries for the jobs to be run each day. Train your staff on  loading the proper color libraries and checking proofs to see if they “Pass or Fail,” and quickly and efficiently correcting any color shifts on press by using the values automatically calculated on the SpectroDens display.
Outcome: Visual inspection of color swatches has been replaced with far more accurate color scans, and customer satisfaction has increased in direct proportion with the color consistency coming off their presses.

Step by Step Procedure: 

SpectroDens Calibration Procedure:

1. Press the green button to turn unit “on.”
2. Use up arrow to go to “Calibration.”
3. Turn wheel on charging base so white ceramic tile is visible.
4. Place unit on the charging base.
5. Push green button once to calibrate.
6. Turn wheel on charging base so ceramic tile is no longer visible.

 Create Color Book/Library:

1. Connect the instrument to a PC running SpectroConnect.
2. In SpectroConnect, right click your mouse in white area under “Color books” and select “New color book (PC).”
3. A color book named “New book” will appear.
4. On the SpectroDens instrument, use the up arrow to go to “Reference.”
5. Press Enter (sideways arrow) to open the dropdown menu.
6. Use the down arrow to go to “Save automatically” and press the Enter key. A check mark will appear to the right. Hit the red button to exit this menu.
7. Place the SpectroDens instrument over the ink draw down or desired color reference target and take a measurement.
8. The measurement will be automatically named “Reference” with a number appended to the name (i.e., “Reference_24” and will be displayed on the left side of the SpectroConnect software under “References”).
9. Drag and drop the new color to the white area under “Colors.”
10. Rename the color to a name of your choice.
11. Go to the “File” pulldown menu and select “Save color library as.”
12. Name and save the Color book.

Load Color Book/Library on Instrument:

1. Open the color book/library.
2. Drag and drop the color book/library to lower left window, under the Start button.
3. Press the Start button. The SpectroDens will display an “Update” message. Color book/library is loaded when “Update” message is not displayed.

NAVIGATION BUTTONS

Instrument Automatically Selects Reference Color:

1. Use up arrow to go to Reference tab.
2. Press Enter (sideways arrow) to open drop down menu.
3. Use down arrow, select “Search Automatically” and hit the Enter key (sideways arrow).
4. Hit red key to exit drop down menu.

Select Reference Color:

1. Use the up arrow to go to Reference.
2. Press Enter (sideways arrow) to open dropdown menu.
3. Use down arrow to go to Select and hit the Enter key (sideways arrow) to see list of colors.
4. Use up or down arrow and select the color you want. Hit Enter.
5. Hit red key to exit drop down menu.

Measure Sample Color:

1. Use the down arrow and go to “Sample.”
2. Place SpectroDens on the area to measure.
3. Take 3 measurements by pushing the green button, move to a different area to measure, push green button a 2nd time, move to another area and press it a 3rd time.
4. “Pass or Fail” will be displayed on the screen.
5. The lower the _E number the more accurate the color.

Maintaining Brand Standards with Color Guide

  

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by Chris Colt

Focus on Features: Color Guide  
This function (formerly known as Ink Check) is found on the SpectroDens Premium, SpectroJet Pro and SpectroDrive Pro instruments.  The Color Guide Feature is a great tool to support intiatives related to maintaining brand standards.

1. What is this function / What does it do?  The Ink Check function is a unique Techkon function that combines the measurements of Density and Color (L*a*b*).  When operating a printing press an operator can either add ink to a roller or remove ink from a roller which controls the ink film thickness or “Density” of an ink.  Customers are now requiring more accurate data to show that their press run was printed within certain corporate brand or industry specifications.  This requires more advanced measurements including Color (L*a*b* and Delta E) data.  Learning and understanding L*a*b* can be very difficult and there are no L*a*b* knobs on a printing press so the operators can become confused by this information.  They may understand that they need to keep the Delta E (DE) below a certain threshold (2.0, 3.0, etc.), but they may not understand how to get there.  The Ink Check function shows the press operator the current Density and Delta E as compared to a standard color stored within the device.  It then shows that a lower DE can be achieved by adjusting the Density Up or Down a certain amount. 

2. Why is it important?  This is an important function as it makes it easier for press operators to understand and implement Color (L*a*b* / DE) controls within their pressroom.  It is a unique function not available on most of the competitive instruments in the market today.

3. Why do customers need this type of functionality?  Customers need this type of functionality to better meet the demands of today’s print buyers and print specifier’s.  They are requiring tighter tolerances to maintain brand standards and to reduce waste due to “bad” color.

A Short History of the Spectro-Densitometer

  

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by George Adam

Over the last 15 years, the trend has shifted from traditional CMYK densitometers to spectrophotometer based densitometers. This shift was mainly driven by more affordable, lower cost technology and the need to know more about the characteristic of the ink that is being printed. This has created a new class of products called Spectro-Densitometers.

Spectro-Densitometers are catching the eyes of press operators everywhere.  Historically, they’ve had to rely on their eyes to calibrate the press, and many still do.  But let’s face it; this method can be cumbersome at times, somewhat inaccurate, and expensive (in terms of time and materials).

The advantages of a Spectro-Densitometer are:

Accuracy and Reliability.  A traditional densitometer uses film filters, such as the Kodak Wratten Gelatin filters, that separate the Cyan, Magenta, Yellow and Black colors from which the density of the ink on paper is measured.  These filters are sensitive to moisture and high temperature.  When the filter degrades, incorrect measurement values are produced.  The CMYK filters are designed to measure the maximum absorbance region of process inks.  Non-process inks that are often used in spot colors can be difficult to control using the non-optimal CMYK filters.  A Spectro-Densitometer uses 16 or more bandpass functions to divide the visual spectrum up equally.  These instruments produce a spectral fingerprint of the material measured.  From the spectral data, all forms of color and density data can be accurately derived.  The extra data allows a spectrophotometer to be a versatile tool that can control process and non-process inks.

Detection of Ink Contamination.  This common problem can be caused by many factors such as by unintentionally laying too much of one color of ink on the paper which then gets carried through the press to another ink fountain.  Since contamination impacts the high reflectance region of an ink and not the maximum absorbance region, a densitometer is blind to the phenomenon.  The versatility of the spectrophotometer allows it to provide other useful metrics, such as the L*a*b* values and the resulting hue which quickly identify ink contamination. These same capabilities allow for new control strategies such as those described in industry standards like ISO, SWOP, GRAcol G7™ etc. 

G7 calibration process.  This process monitors a gray series as well as the primary inks to accurately maintain near neutral colors.  With such a process, the color fidelity of the printing process is greatly improved.  (This process relies heavily on maintaining near neutral color for the gray color by measuring the L*A*B of paper white and subtracting the color of the paper white which is not perfectly neutral white.

Going Outside the Box with SpectroDens MiniExpresso

  

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By Glenn Andrews, Color Clarity

One of the great advantages of printing to standards is having a known target to aim for. ISO 12647 indicates precise L*a*b* values for offset CMYK solids when using ISO compliant inks with ISO compliant paper.

But what do we do to establish proper ink density targets when no standard exists? Printing onto unusual substrates such as plastics or synthetics, printing to “G7 Extreme”, or printing using unusual techniques are all examples of important non-standard printing proceses. Without an established guide to optimum ink levels, it is up to the printer to determine proper target densities.

In many printing processes, ink reaches a point where increasing the amount of ink on the substrate yields little gain in terms of density or increased color. Ideal ink film thickness will be levels that yield maximum density while retaining control over reproduction.

Additivity Failure in Dye Sublimation

A good example of this is the dye sublimation process, When the polyester receiver has reached its point of maximum dye absorption, “additivity failure” sets in, and increased ink film thickness no longer contributes to increased density on the final product. The result is wasted ink and impairment of the ability to control the process.

The best method for determining optimum ink film thickness is to run a test form of solid horizontal ink stripes with ink keys on each color unit set from low to high across the sheet.

The result will be a press sheet with densities going from too light to too dark across the sheet, with optimum levels somewhere in the middle. The task is to find the point where near-maximum densities have been achieved but additivity failure has not yes set in.

Finding the Sweet Spot

Using the Techkon SpectroDens,  select the “Mini Expresso” option. Starting from left to right, take density readings at each ink zone. Mini Expresso will record each reading and display final density values in both numeric and graphic forms. Typically, final density values will rise from left to right as ink film thickness of the donor sheet increases.

However, at a certain point, final density values will reach their maximum absorbency level and additivity failure sets in. At this point, increasing ink film thickness on the donor no longer results in increased density on the final receiver substrate.

In the illustration above, taken from a dye sublimation press test, maximum density is reached at 1.72, and no increased density is reached after this point, even with increased ink loads. There is in fact a serious downside to exceeding maximum practical inkloads, as this will lead to a loss of shadow detail that cannot be corrected with curves.

So in this case, optimum ink load is reached at  approximately 1.64: near the practical limit while still retaining control over shadow detail leaving a cushion for normal process variation. Using SpectroDens MiniExpresso makes it easy to find the area of maximum practical density.

Is it time to upgrade your densitometer?

  

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by Dan Reid, RP Imaging

In my travels helping companies achieve G7 Master Printer Certification I encounter lots of creative ways of managing color on press. Lots of folks have a densitometer at the press console to spot check sheets. While this has undoubtedly greatly improved the consistency of press color on each station over time it becomes obvious that some densitometers do not correlate to each other when measuring the same press sheet and ink zone. Which densitometer is correct?

One resolution is to send a densitometer back one at a time to get re-certified by the factory. This will ensure at the very least the factory has confirmed the device is operating and performing within acceptable measurable tolerances defined in the certification sheet included in the return shipment.

Is your densitometer measuring accurately?
Techkon takes this crucial concept one step further enabling their customers to verify multiple instruments to measurements alike in-between factory recommended re-certifications (24months). Connecting a Techkon SpectroDens by USB to PC running Techkon's Connect software and Techkon Spectrocheck module allows multiple SpectroDens to be verified against a color reference. The Techkon Spectrocheck consists of four colored ceramic tiles that rotate on a lazy susan style cradle.  The verification process is easy with the Techkon Connect software showing pictures of how the device should sit in the cradle. A label can be printed with the results of the verification.

G7
The G7 near neutral calibration method is established in US commercial printing industry as a preferred method for press and CTP calibration. Many of our commercial printing clients have older densitometers prior to the G7 revolution. Though we are able to show them how to correlate correct target solid ink density measurements for their densitometers invariably they are enamoured by the bold simple display of the Techkon SpectroDens for G7 refinement. The Techkon SpectroDens displays corrective moves that a pressman can immediately implement on the press console. Older  spectrodensitometers do not display “press moves” on the LCD screen, nor do densitometers offer this functionality.

What's your shop's colorimetric tolerance?
One of the lively discussions I like to have with a pressmen is what is an acceptable deviation allowed across the sheet? I have heard a lot of interesting explanations of how and why their tolerances are meaningful and absolute. Sometimes I hear differing explanations and tolerances from pressmen at the same plant!

Simply put measuring variance across a press sheet should be done using a meaningfully weighted color differencing models of CMC, dE2000, and dE94. These color models provide a good correlation between what we perceive and what the measurement device is reporting. Metrics of density do not correlate well to human perception but are excellent at recording meaningful variances.

A tool I find helpful for spot checking different ink zones against one another is the SpectroDens InkCheck. Instead of relying upon density, which does not correlate to how the eye responds, the SpectroDens InkCheck uses spectral (colorimetric) measurements to see what variance in Delta^a*b* is occurring across the press sheet. Using colorimetric delta-e is a simpler and safer method since the defined variance have real world implications to the viewer. The CMC, dE2000 and dE94 tolerances are weighted based upon continued research in how humans respond to color. Therefore it is easier to define a shop's tolerances as delta^a*b* to ensure similar color quality across different presses and operators.

Densitometers can't report this useful metric. Older spectrodensitometers can be upgraded to report some of the new G7 metrics but fall short in displaying an easy way for operators to use in production. Start extrapolating how much it costs to not move jobs around because the color match can't be consistent, then think about the waste/spoilage that happens from everyone sharing numbers (SID) around the shop that result in further problems in achieving similar quality printing among presses.

An easy way to minimize a shop's color variance among presses is to use instrumentation from the same manufacturer. The Techkon SpectroCheck ensures instrumentation is working with tolerances between factory recommended re-certifications.

-- Dan Reid is a color management and G7 Certified Expert at RPimaging, INC.

RPimaging, INC helps clients achieve the benefits of G7 calibration in a matter of days. Learn more about RPimaging, INC services and products at http://www.rpimaging.com

The Good News, The Bad News, The Good News

  

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by Glenn Andrews, Color Clarity

Life can be a series of ups and downs, and instituting a process control system can follow the same zig-zag pattern, but with one important difference: With process control there are a lot more ups than downs.

First the good news: having automated process control on press has never been as inexpensive and easy to implement as it is now. Clear standards and methodologies exist, proofing is better than ever, and true automated spectral scanning is now available for a fraction of the price that crude density-only systems cost only a few years ago.

Now the bad news: Once you start scanning full-width color bars on all your press runs, with graphic display of primary and overprint L*a*b* data, TVI or Dot Gain, gamut volume and gray balance, you are liable to discover that your press may not performing as well as you thought it was, and maintaining adherence to standards seems to be near-impossible.

Finally, the really good news: The data gathered with regular scanning of press sheets makes it easy to diagnose and quickly solve long-standing problems that had been costing you thousands of dollars, and get back on track for radically reduced make-ready times.

A client recently went through the up-down-up process and is now thrilled with the improved results and reduced costs he is experiencing. Starting from the usual outdated densitometer-plus-eyeball method, he switched to full sheet spectral scanning. The results were immediate and impressive, but he soon began to notice problems he had been unaware of: the dot gains were unpredictable, yellow was frequently contaminated, and deltaE’s on overprints were unacceptably high.

Armed with detailed reports from his scanned press sheets, he called in his ink and chemical suppliers for help. They found problems with ink tack sets, an improperly calibrated fountain mixture pump, and defective Ph and conductivity sensors. None of the problems were expensive or difficult to fix, yet they had been contributing to large and unnecessary costs in terms of make-ready time, paper waste and lost opportunity for months or even years, and yet there has been no awareness of these problems until he began regularly measuring every press run.

With hidden problems uncovered and fixed, quality is up and costs are down, and it was made possible by putting a little bit of bad news to good use in a process control improvement program.

3 Industry Trends Every Printer Should Know About

  

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by Glenn Andrews, Color Clarity

All sorts of new trends are happening in the communications arena: variable data printing, QR codes, cross-media campaigns, internet marketing and more. There’s plenty of buzz, and the farther it all is from traditional printing, the more printers feel they need to know more about it.

So is there anything new to talk about in traditional print? You bet there is! Some of the most powerful trends developing right now are all about putting ink on paper in completely new ways.

Ever-Shorter Pressruns: OK, this particular trend may not seem new, but the implications of short pressruns change the dynamics of printing in surprising ways. Now it is more important than ever to have tight process controls in place, to be aware of any color shift trends on press, and to have a concrete plan for dealing with these changes.

The old attitude of “This is a short run, we don’t have time to get up to the numbers” has been turned on its head. With ever-shorter pressruns, getting to the numbers quickly is the only way to make a profit.

High-End Commodity Printing: Printers often complain that customers now regard printing as a commodity; that price is everything and quality doesn’t matter. Well, that’s over. Now customers want quality and price: High-end commodity printing is here.

Can a printer make money given this seemingly impossible equation? Printers who understand the model will do better than ever. High-end commodity printing means that the printer will manufacture printed product to industry specifications, and the customer will base OK’s on meeting these specifications.

Notice that I said manufacture. Craft and artisanship (the old models of print) are notoriously more expensive and inefficient than manufacturing, so printing to this new model means that it can be done less expensively while maintaining quality.

BPO organizations. BPO’s, or Business Procurement Outsourcing organizations started out by providing turnkey support services for companies that wanted to focus on their core competencies and buy out the rest. Now some BPO’s have focused their efforts on print buying and many are doing it with the high-end commodity model in mind. To some buyers, BPO’s wear the black hats, but to the printer who knows how to meet their specifications, they can be very important customers.

What these three trends have in common is that they all place a strong emphasis on the role of measurement in print. The old methods of pulling tricks out of a hat and of “seat of the pants” printing have reached the end of their useful lives. Printing now requires the same measurement and process control based approach that all other manufacturing processes have always used, and the printers who succeed in achieving process control through measurement will benefit from these new trends in print.  

Tricks of the Trade When Measuring Color

  

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by Sam Swartz

Here are just a few tricks of the trade when using a densitometer or spectrophotometer to measure color:

Calibrate
Always be sure to calibrate the device on its matched calibration plaque.  Experienced users tend to get lazy or rushed and forget this critical step.  And, often time’s new users overlook the importance of calibration.

Handle with Care
It is very important to hold the device down gently and evenly when measuring color patches; even slight movements can cause erroneous readings.  Remember not to rock the device!

Aperture Size
It is always best to use the largest aperture you can for the sample being measured as we all agree that more information is better.

Average Measurements
A great way to even out the inconsistencies in the sample and avoid measurement errors is to take three measurements and use the average measurement.

Instrument Care
Many users underestimate the importance of caring for the instrument properly.  Always keep the instrument clean and dust free.  This can be done easily by gently blowing off the optics with canned compressed air (oil and moisture free).

Measurement Analysis Software
The software application displays measured values to track the accuracy of what is being printed in comparison to target values.  It will also generate a detailed trend analysis to demonstrate to the customer or in-house quality managers how well the press run performed.

5 Reasons for Color Management in Packaging

  

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by Bob Byrnes

5 Reasons to Adopt a Color Management Process in the Packaging Industry

1.  Is your ink really the right color? How can you tell?

Determine whether the color of the ink you are receiving from your supplier falls within an acceptable distance from the customer specified colors and tolerances; before the end of the press run. Follow these 3 simple steps:

1. Have the ink supplier provide an ink draw-down on the actual press material you are going to print on along with the customer specified color values (Lab) and how close the ink is to the specified color (∆E).
2. Use a Spectrodensitometer to check the color of the ink draw-down to verify that it is within the customer stated color specification and tolerance.
3. Measure what is being printed at regular intervals to determine if the color is still within customer tolerances. Swapping in a new bucket of ink may cause unintended color variation consequences.

These 3 steps are an easy way to control ink color variations that can ultimately lead to costly remakes and wasted materials.

2.  Checking density is not checking color.

Density is the amount of ink being printed in a given area. Measuring density is not a method for checking color.  A Spectrodensitometer color measuring instrument is ideal for qualifying whether the color being printed is within the customer color specification and tolerance. It can help determine whether extender needs to be added to the bucket of ink, whether the PH needs to be adjusted or a new bucket of ink should be swapped in.

3.  Maintain good color between different presses, shifts and print facilities.

There are three main elements to minimize unacceptable color variations between different shifts, presses and print facilities on the same customer job:

1. Use a Spectrodensitometer color measuring device. A Spectrodensitometer will measure the color being printed and compare it against customer approved color specifications and tolerances.
2. Make sure that the different shifts, presses and print facilities are using the customer approved color specifications and tolerances to check that the color being printed is accurate and within the customer stated tolerance.
3. Color control trending software that can keep track of the performance of a specific job and produce reports indicating to the customer or internal quality personnel how well the press run performed.

4.  Understand how the color of your packaging material effects the color of your print job.

The color of your printing material can substantially influence the accuracy of the color being printed. Since inks are not 100% opaque the color and texture of the material that is being printed on will show underneath the ink being laid down on press and cause a visual color variation, sometimes substantial.

Using a Spectrodensitometer to measure the print materials ensures consistent color between rolls. It will also help you better predict the impact the color of your print material will have on the end-result printed piece.

5.  If you are not measuring color, how can you control it?

The best method for controlling color is to actually measure color. A Spectrodensitometer will measure the color being printed, compare it against the customer color specification and qualify and quantify whether it is within expected tolerances. Measuring color lets you consistently fulfill your customer’s requirements and expectations.