Quality control: Making sure you are in spec

By Ron Ellis

Quality control can mean many things in a printing plant, but often it means making sure that the printed product meets or exceeds the quality that we expect from that plant. This can be measured in a variety of ways, but the truth is that is most often done visually and that deviations are not noticed until too late in the process.

Noticing problems or press, or even worse — after the job has been printed — can be a disaster. By observing the workflow in many printing plants, it could be concluded that Quality Control does not matter, and that printers are not paying attention to the drift — both on proofs and printed products. This is obvious through common answers to questions such as:

The answers are readily known in some plants, but in many others there are no answers. Many printers remain convinced that the effort required to track quality control is not worth it, and will state that in some environments quality control at that level is important —  but not here.

               Are quality control tools necessary? Jim Raffel, of Colormetrix believes it is. “I feel quality control tools are necessary in the printing industry for the same reason one needs a map when driving between two points.  Picture trying to drive from Boston to New York City for the first time without a map.  Is it possible?  Yes, is it far easier and faster with a map? Yes, just as producing quality printing is far more productive and profitable when you know where you are and where you need to be.”        

Chris Colt from XRite says QC tools are necessary to track the performance of an output device — whether proofer or press — and determine when a certain device needs to be calibrated back to a standard or starting point, or there is another issue to be address.

“A QC program can catch a bad batch of media, the wrong media, a clogged ink nozzle or if the wrong profile has been applied to the job,” Colt said. “On press, printers use densitometers and spectrophotometers to check the ink film thickness and/or color of the printed sheets. Many times nothing is done to track the these issues, and by the time a color issue is realized, you are on press and are unable to color correct at this point.”

There are a variety of quality control tools that are available. They tend to be used for checking a proof for drift and quality, and checking a press for gain, drift, and quality.

The tools can be used to simply check against a benchmark, or they can be used to improve quality by showing what a press or proofer is doing, and how to improve that quality against a standard such as GRACol or SWOP. While these may seem like simple applications they can be used in a variety of ways.

For example at its most basic, a quality control application will provide a simple pass/fail. In some shops such as a small commercial printer, they may run a pass/fail QC test once a day to make sure the proofer is not drifting. In other shops, such as a color separation house, they may run a check on every proof and then paste a label on each proof signifying a pass or fail.

A company with a product brand to control may require each vendor read each proof and partials from a pressrun, and then store those results in a database for tracking and reference over a network.

No matter what the scale of quality control procedures, there are some simple reasons people are using these tools. The prepress manager uses it to make sure the proofs aren’t drifting and to protect himself against accusations from the pressroom.

The pressroom may use it to confirm quality and to trend and improve quality on press. Customers may use it to make sure printers are in spec, or to prove to printers that their proofs are in spec.

The quality control software market for the graphic arts is small and there are only a handful of products. The leading tools are ColorMetrix Proofpass.com, XRite QC Color, and Color Sciences CrossMatch. Nearly all proofing vendors offer simplified products that can give you a quick pass/fail. (See last months article on proofing and linearization for more information.)

Most of these products come in simple stand-alone versions or more complex network versions. With these products the user scans a colorbar or strip, which is compared to a reference strip. The user can set the tolerance as tight or as loose as desired and the software generates a pass/fail message. The user can then print a label or report.

With network versions the results are sent to a database so that other users can see and evaluate the results, and track proofs or press sheets over time. Many of these products will also give you an idea of what is wrong with the proof and present you with statistical data.

“The ability to catch and label a bad proof before it disrupts your workflow is important,” said X-Rite’s Chris Colt. “With QC Color you receive automatic email notification when a proof/target fails. By labeling good proofs as “passed” you know that they have passed some type of benchmark for consistency.

“You can also use the database to track data related to a proofing system over time, and look at information related to operator performance, media, inks, devices, etc.,” Colt said. “XRite QC Color also allows you to track multiple proofing systems across one facility or multiple facilities and store data in one central location. XRite QCColor tracks Color (L*a*b*, Lch), Density, Dot Area, Hue & Grayness.”

Also important is the ability to share data with multiple users. “ColorMetrix' new ProofPass.com solution offers cross platform (Mac and PC) print certification and process control,” said Colormetrix’s Jim Raffel. “In addition, because all results are stored on the Internet, true remote color diagnostics are a reality. The prepress house, printer, and color consultant can all see the same information and color at the same time in web-browsers.”

While powerful, the products aren’t inexpensive. They range in price from $800 for simple pass/fail tools to more than $5,000 for pressroom tools and advanced network capabilities. The basic tools are valuable for anyone who needs to know that their proofing system is not moving and staying stable. The advanced tools allow both network capabilities and in some instances pressroom tools. Despite the costs, monitoring color is important, and these tools provide an easy way to do it.

 

About the author: Ron Ellis is a prepress consultant specializing in workflow training and integration. He worked in the commercial printing industry for 18 years and brings a strong background to all aspects of prepress. He has consulted on numerous CTP installations and he provides color management, integration, training, workflow development, and trouble shooting solutions to the graphic arts community. He can be reached at 603-498-4553 or through his web site at www.ronellisconsulting.com