Tuesday, January 15, 2019

The Changing World of Post Print Corrugated

Let’s face it printing on corrugated media has been plagued by fluting problems from the very beginning. What is fluting you ask? Fluting is an area of print having higher gain along the tops of the flutes versus in the valleys between them. This print density differential gives the appearance of the printed piece of corduroy striping running along the flutes of the board. For those visual learners (we love visual learners!), the photo below shows heavy fluting on the left and minimal fluting on the right.

The Change to Digital
For years, analog printing plates performed acceptably with minimal fluting; however, in the early 2000’s the print industry’s workflow started changing…enter DIGITAL PREPRESS. This workflow lead to an increase in the use of digital flexo printing plates. Unfortunately, digital printing plates tend to flute worse than their analog counterparts due to the geometry of the rounded printing plate dot and the edges of type and solids. This rounded surface and the contact angles with the uneven corrugated media contributed to the visual appearance of the printed flutes. As more companies embraced the digital workflow and use of digital printing plates increased, printing plate manufacturers and trade shops had to work closely to reduce the effects of fluting using this new digital process.

Change in Measurement

To better understand and measure the fluting effect, MacDermid Graphics Solutions created a device that could measure printed dot size across a wide portion of printed corrugated material. When these measured printed dot size readings are plotted, you can easily see the visual appearance of the printed flutes in a graphical chart. This use of a graphical measurement made it easy to identify and measure the difference between the average printed dot size from the top of the flute to the average printed dot size from the valley of the flute. The difference between these two numbers are what we called the Fluting Factor. The higher the number, the more noticeable the fluting is in a printed piece. If the number is small, it corresponds to a very smooth print appearance and lower visual fluting within the printed piece. The following photos and corresponding Flute Factor readings will illustrate how this matches up with the visual appearance that is seen with the naked eye.
Graph of a printed scan with a Fluting Factor of 2.90
Printed Board with a Fluting Factor of 2.90
Graph of a printed scan with a Fluting Factor of 4.13
Printed Board with a Fluting Factor of 4.13

Plate Changes
Using the information from a Fluting Factor Study, MacDermid Graphics Solutions engineered a solution for digital plates to address the fluting issue in 2010 with the introduction of the LUX® process. The LUX process helped printers minimize the fluting effect by laminating a thin coversheet to the digitally ablated printing plate which, after exposure, produced flat printing surfaces. MacDermid then introduced the Digital MacDermid Anti Fluting (Digital MAF) plates in 2015. Digital MAF was the industry’s first digital corrugated plate that provided a flat top printing surface right out-of-the-box. The proven results gave platemakers a digital plate with a flat printing surface without the need for additional procedures, equipment, or consumables. With a 32 Shore A hardness, Digital MAF plates also offered a new dot shape optimized for even greater fluting reduction and dot gain performance against competing flat top technologies at the time. This engineered shoulder structure has an angle break in the sidewall of the print character which provided additional relief from the printing pressures to help lower the amount of impression provided to the printing dot. This pressure reduction helped decrease print gain and eliminate the distortions at the media interface while allowing for good surface contact to deliver excellent solid ink coverage.

Conventional Digital, 85 lpi at 3%

LUX Digital, 85 lpi at 3%

Digital MAF, 85 lpi at 3%  

Changes in Corrugated Board
As the corrugated post print reproduction market continues to evolve, the industry is looking to save on raw materials without compromising quality. This created a trend to down-gauge corrugated boards and use paper grades with increasing amounts of recycled content. At the same time, the industry is seeing increased graphic requirements as the flexo market attempts to grow at the expense of Litho labels. Printers and brand owners demand and expect high quality printing regardless of the board quality.

The conversion to higher recycled content and lower basis weight boards brings a new challenge to the corrugated printer…How do you retain smooth solid ink coverage, print crisp half tones and fine type while minimizing board crush? The higher recycled fiber content produces a different surface compared to the corresponding virgin liners of the same basis weight due to the additional processing steps needed to prepare the recycled content for reuse. Attaining good ink coverage on recycled board many times results in the need for additional printing impression to obtain smooth laydown which, many times, could lead to board crush. Board crush, if excessive, could lead to structural changes in the printed sheet affecting structural integrity of the folded box. This shift in business conditions highlighted a need for softer plates that offer high graphic reproduction abilities and the ability to minimize board crush using these evolving types of corrugated media while providing good solid ink coverage.

Changes to Avoid the Crush
Never satisfied, MacDermid Graphics Solutions answered this need by expanding our digital plate technology to include the new LUX® In-The-Plate™ (ITP) MELO. This plate is specifically engineered as a super soft, digital photopolymer sheet plate for use with post print corrugated board. With out-of-the-box flat-top plate technology and a 25 Shore A hardness, LUX ITP™ MELO produces printed results with excellent tonal reproduction and extremely smooth solid in coverage.

LUX ITP MELO is the only commercial 25 durometer plate that offers out-of-the-box flat-top dot capabilities with outstanding imaging capabilities.  This plate was designed to hold 1-2% dots at 133 line and consistently hold open the 95% shadow dots which eliminates the printer’s need to split out plates that have combinations of large solids and fine type or process color within a plate. This allows for additional savings in plating jobs and a reduction in the number of print decks used.  With the unique engineered dot geometry introduced with the Digital MAF plate and now the LUX ITP MELO plate, printers are seeing excellent results printing high line process color using such a soft plate. The dot’s unique sidewall construction eliminates the typical bulge near the print surface that contributes to excessive print gain or doughnut dots and small type. The softer 25 Shore A durometer has also demonstrated improvements in the amount of board crush measured after printing compared to the typical 32 Shore A printing plates, the industry standard for the corrugated market.

Don’t Forget About Liquid
While there has been a significant amount of work and research completed to improve digital plate technology, liquid photopolymer plates are still widely used in the corrugated market and continue to print extremely well with minimal fluting. To compliment the advancements of LUX ITP MELO, we added LTS, a new liquid photopolymer to our industry leading M System™ portfolio. LTS is a 25 Shore A hardness photopolymer featuring the same attributes as our flagship liquid photopolymer, LTL, a 32 Shore A hardness material. These two liquid corrugated photopolymers are designed to offer top protection from the conditions that are typically faced in a corrugated box house such as ambient UV Exposure, Heat & Humidity Resistance, and Ozone Exposure while in storage. While both deliver excellent ink transfer on all types of corrugated board, LTS offers the same benefits as LUX ITP MELO for use with lighter basis weight boards and those with higher content of recycled fibers.  For those liquid manufacturers that have not moved into the digital platemaking process, we also introduced another new photopolymer, M Cap 45. This 45 Shore A durometer photopolymer was developed for use with the softer LTS or LTL photopolymer to provide the ultimate straight side-walled, flat topped printing plate for use with process color and fine type. M Cap 45 is cast as a thin layer of photopolymer against the photographic negative so that it becomes the printing surface and LTL or LTS is the softer base material forming the lower shoulders and floor of the printing plate.

Capped liquid plates have always demonstrated the least amount of fluting of any photopolymer plate due to the flat top printing surface, nearly vertical shoulders, and the dual durometer construction of the printing plate. Any distortion from excessive impression caused by press setup or an uneven board surface is handled down the print wall, far away from the printing surface as demonstrated in the attached photos.

Uncapped liquid plate
Capped liquid plate    
Capped liquid plate under load

Printed Board using a Capped Liquid Plate

Printed Board using an Uncapped Liquid Plate 

The Takeaway
With old challenges (fluting) and new challenges (board crush and high graphic requirements) the world of corrugated post print reproduction is continually changing. Using soft sheet or liquid photopolymer plates developed for these challenges is key to meeting the demands of brand owners. As the market moves to create savings using lighter basis weight boards with more recycled content and an increasing expectation of higher and higher print quality demands, flexo printers and plate manufacturers must continue to evolve to meet requirements in corrugated print.

To elevate your corrugated post print reproduction to the next level, contact MacDermid. Email us today.

Based on article, The Evolution of Corrugated Print Reproduction” by: 

Dan Fry, Portfolio Manager, Corrugated - MacDermid Graphics Solutions

Dan Fry, Portfolio Manager, Corrugated at MacDermid. Fry earned his Bachelor of Science in Chemistry from the University of Delaware in 1981 and joining Hercules Incorporated that same year. He moved to MacDermid with the sale of the Electronics and Printing Division in 1995 and has since served in various Technical and Sales Management roles since joining MacDermid.

Thursday, January 3, 2019

Let's Talk About Flexo Plates

Flexographic (aka Flexo) printing quality rivals the quality of both offset and gravure. Is this the first time you heard this? Probably not! If you are reading this blog you are likely aware flexo is the #1 print method for flexible packaging in both the United States and Europe. The evolution of flexo from a somewhat viable option to the #1 choice is multifaceted with advancements across the entire printing process. One major factor is that flexo printers are optimizing their processes with flat-top dot photopolymer printing plate solutions. It’s been said, to do a job correctly, first you must have the right tools. In today’s flexo printing market, having the right plate (the tool) can make the job easier, more consistent, and ultimately more profitable.

Flat-Top Dots
The packaging market consists of four major market segments: flexible, tag & label, folding carton, and corrugated. MacDermid Graphics Solutions (MGS) has an out of the box, flat-top dot solution for all markets called LUX® In-The-Plate™ (ITP). Why use a flat-top dot plate? Flat-top dots offer increased impression latitude, print consistency, and faster press start-ups. In addition, with MGS’s LUX ITP technology, you get near 1:1 imaging with an optimized dot structure for better wear characteristics. What does that mean for you? With the bump curve greatly minimized, that means you have now opened up your tonal range to print a wider range. This can give you cleaner vignettes, better highlight definition, or allow you to hit those “impossible” spot colors with process color inks. Since launching LUX ITP™ in 2016, MGS customers tell us these plates “even-out” the skill level of their press operators. In other words, they don’t have to worry about having only their best operators run critical jobs that would normally require a very light impression set.

Photo Credit: Vibrant Media Productions, LLC 
The Choices
OK, you want the best print, right? Well…you need THE BEST plate. But which plate do I choose and where do I start? Begin with plate durometer. The plate durometer impacts the print job. Each market segment has its own general plate durometer requirement due to the substrate being used:

• Soft (~ 20-30 Shore A) durometer for corrugated
• Medium (~ 50 Shore A) durometer for folding carton and narrow web
• Hard (~60 Shore A) durometer for flexibles, usually wide web film applications

MacDermid measures Shore A using the ASTM standard by measuring the photopolymer stacked to 0.250” thickness without a polyester backing, giving us the polymer’s true Shore A number. We can also measure the effective plate durometer using the same instrument, providing a relative measurement of the plate durometer at the specific gauge at which it will be printed. For example, our LUX ITP 60 plate, a 60 Shore A at a 0.250” stack, measures 68 durometer on an 0.067” plate. The durometer is an important number to know when choosing your plate, and is a factor to consider for each market segment.

The Markets
The corrugated market requires an extremely soft plate. This requirement is driven by the construction of the print media itself – balancing print performance with packaging strength requirements. On the print side, corrugated printers require a plate that will be soft enough to cover recycled Kraft board, but not too soft that it’s a detriment to printing a continuous tone image. By using a softer durometer, the plate can conform to the texture of the substrate and print a smoother solid without crushing the structure of the corrugated board. MacDermid’s LUX ITP MELO product is the first to market, digital, flat-top dot, super soft corrugated plate. With a 25 durometer Shore A at 0.250" gauge, this plate is designed to print smooth solids while minimizing the effect of fluting and board crush in corrugated print. LUX ITP MELO’s super soft shore A and dot profile are the key attributes to minimizing board crush and fluting. More Information on LUX ITP MELO

Tag & label and folding carton printers have traditionally used medium durometer plates. This requirement was partially driven by the need to wrap a plate around a very small cylinder. THE IMPORTANT PART… the plate needs to wrap AND stay in place for an extended period. Certainly, the mounting tape plays a part in keeping the plate down on the cylinder, but more on tape later. Printing plates for this market print clean, high-quality graphics for long periods of time. MacDermid engineered LUX ITP M with these requirements in mind. LUX ITP M features very low tack which makes dust and debris, present in some paper stocks, no longer a factor. The durometer of LUX ITP M is a little firmer than most medium durometer plates so it can be optimized for wide web applications as well, but it retains the high flexibility required for the smaller print cylinders. 
More Information on LUX ITP M

For flexible film printing applications, most printers use a harder durometer plate. These plates typically start off around 60 shore A. Again, this measurement is taken at 0.250” thickness and without a polyester backing. Having said that, there are several printers today using plates that have an effective durometer in the low 70s or even higher. Most wide web printers need a plate that is harder to ensure the very best dot reproduction on their substrates. A plate that is too soft for the application can print with slur or excessive dot gain. LUX ITP 60 was the first flat-top dot in-the-plate product on the market and subsequently won the FTA Technical Innovation Award in 2016. LUX ITP 60 provides outstanding print quality and consistency, minus any extra steps needed to achieve flat-top dots. More Information on LUX ITP 60

Photo Credit: Vibrant Media Productions, LLC 

Flexible film printing struggled to attain a balance of low dot gain with good solid ink density and coverage. Cap technology was the solution. A cap is a micro-rough layer on top of the photopolymer printing plate that aids in the transfer of ink onto the substrate. Think of it as something like sandpaper- with peaks, valleys, and crevasses that allow more ink to be picked up by the plate. This allows the best of both worlds - a hard plate that gives you good dot reproduction WITH good ink transfer. Then came surface screening technologies allowing you to build the microcells in the image file, becoming favorable over capped plates. While prepress screening technologies are great, they require a high degree of process control on your press. The skills required, combined with the decrease in prepress specialists, means the simplicity of cap technology is desirable. And now…The Cap is Back! The introduction of new capped plates with inherent flat-top dots like our LUX ITP EPIC® plate, provide the print consistency and high solid ink density needed to produce the finest detail graphics on flexible film. More Information on LUX ITP EPIC

About that tape…
It’s important to understand that the durometer of the plate shifts as the plate gets thinner because there is less material and more influence from the polyester backing. The effective durometer is also influenced by what is under the plate when it is mounted...the mounting tapeIt is important to work with your plate and tape supplier to fully understand the plate/tape relationship specific to YOUR printing environment.

Knowing what we know about plate gauge and substrates, it’s obvious why optimizing the entire plate/tape package is an essential part of making sure you have the right tools for the job. One such property – DUROMETER – is an important element to consider during the optimization process.

The Take Away
What did you learn? Choosing the right plate for your printing process is important for your solid ink density, ink coverage, and dot reproduction. A super hard plate has low dot gain making it ideal for your highlight dots, but poor for your solids. In contrast, a super soft plate is great for your solid ink coverage but poor for your highlights, which will result in high dot gain because of the compressibility of the photopolymer dot. As a printer, you must determine what aspect of your printed work is most important to you. Do you print mainly solids and line work, where a softer plate would be beneficial, or do you print high-end process color graphics that would benefit from low dot gain? In today’s flexographic market, starting with the right plate can make the job easier, more consistent, and ultimately more profitable.

To elevate your print to the next level (with the right plate of course), contact MacDermid. Email us today

By: Jason Cagle, Account Manager - MacDermid Graphics Solutions - More About Jason

Based on article, The Right Plate for the Job in the Flat-Top Dot World” by: 

Ronnie Scogin, Applications Development Specialist - MacDermid Graphics Solutions

Ronnie Scogin is an applications development specialist with MacDermid Graphics Solutions. Ronnie has more than 30 years of experience relating to flexible packaging, with the last 13 years spent at MacDermid. Ronnie’s expertise includes proper plate selection and optimization, pressroom auditing and best practices, and plate and print defect troubleshooting. Prior to 2016, Ronnie was a valuable member of MacDermid’s Technical Applications group, working directly with customers in the field across all flexo markets.

Insights to the Corrugated Market

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