By Wayne Peachey, SGS International
Anyone investing in flexographic platemaking technology right now will have a difficult time in comparing products to each other and in justifying ROI (return on investment). Solutions are evolving exponentially, and identifying the “right’”technology that will serve over the time of the investment needs lots of research, some blind faith, and possibly a crystal ball!
The first “flat-topped dot” plate solution challenged the industry to compete, and the varying solutions that have emerged have to go through a few more cycles of development before an actual “winner” is announced. Imagine picking the winner of the 2016 Baseball World Series based on today’s youth players?
Plate production advancements
Not so long ago, flexo plates risked becoming a commodity. Solvent-washed plates, imaged on a CDI, were quite similar to each other as the key processing variables were limited. Choice of plate depended on past performance, cost, service, plus one or two intangibles such as the colour of the photopolymer (oh yes it did!).
The advent of new technologies (broadly referred to as” HD flexo,” although this is a vendor-specific term) has really changed the face of flexo. Improvements have led to a greater diversity of product, and so a more confusing array of variables needs to be considered.
The first technical change came about thanks to the realization that the halftone dots of a plate can be a very different shape if made in the absence of oxygen. These are now referred to as “flat-topped dots,” and it has been proven that these dots lay down the ink in a more consistent and “better” way than conventional round-topped dots. It is believed that their more stable structure helps to provide consistency and quality. The results vary less due to impression, and so they can be more forgiving of variance.
Oxygen inhibits polymerization (yes, this is the technical bit), and so when exposed to UV light, the dots form normally except near the surface of the plate where the presence of oxygen means they become rounded. In the early days (about 15 years ago), it was assumed that a rounded dot was a good thing as the previous alternative was a very broad-shouldered dot.
Since then, we have found that with the new technologies available we can create very precise flat-topped dots that perform much better on press in certain situations. No doubt for patent infringement reasons each manufacturer has created their own method for achieving a flat-topped dot, hence the choice in the marketplace.
A normal plate is processed by first imaging the black carbon layer, then by exposing the plate to UV light, and then by washing out using solvents or heat
The typical techniques for eliminating oxygen are:
- Imaged film is laminated to the plate.
- A film laminate is attached to the normally CDI-imaged plate.
- The normally imaged CDI plate is UV exposed within a non-oxygen environment.
Each method is typically matched with the plate manufacturer’s own products (broadly speaking)
An additional alternative approach has emerged. One manufacturer provides LED lights within the light exposure frame (in addition to UV lights), and this approach creates flatter topped dots. Confused yet?
So, flat-topped dots are an advancement in technology, and when we image a plate (or similar) we are now “holding it all.” This is sometimes described as 1-to-1, and there are lots of arguments surrounding the concept of true 1-to-1.
The next technology to proliferate is 4,000 dpi imaging. Now that we are “holding it all,” we are finding that a typical 3-percent dot is not that pretty; it is shaped more like an asteroid! We like the higher resolution HD television, and we love seeing the dimples on a golf ball when watching the PGA, so why wouldn’t we enjoy better resolution on our flexo plates? As it turns out, we do!
Higher resolution also allows us to be more precise with our highlight dots. Many technologies have been available for many years in an attempt to reduce the appearance of highlight breaks—where the minimum dot (in a vignette, for instance) stops. Samba and other screening techniques have been around for a long time. Thanks to flat-topped dots and 4,000 dpi imaging, our highlight screening choices are greater, and these now perform better than ever.
Solid ink laydown
The next constant in flexo is the difficulty in achieving a good solid ink laydown. Typically, we would need to separate the job to add extra colours, use different backing tapes based on the graphic, use different plate types based on the graphic, or just live with the reduced density and pin-holed solids.
The first offerings of plate cells and grooves in solids overcame many of the issues, and such techniques have been greatly improved thanks to flat-topped dots and higher resolutions, offering an even greater choice of options.
Putting it all together
SGS has worked with many printers across many different presses, testing a range of HD-type solutions.
SGS has been involved in each of the technologies from an early stage. “We have many locations across the globe,” explained Steve Babb, Managing Director at SGS in Hull, UK, “and so as a group we are always looking at the latest ideas and reporting back. This makes it easy to assess and qualify future investments. We also have the best technical and support staff, and they continually work to evolve the application of new technology.
“When we tested and noticed unsuccessful characteristics in one flexo solution, it immediately became an opportunity for us to learn from those results and try another. For instance, plate durometer is important to our customers, and not all HD-type plate solutions have the choice that we require.
“We think we have evolved to a stage in which we can easily challenge gravure on quality, whilst letting the natural benefits of flexo almost sell themselves.”
David Skinner, Senior Sales Manager at SGS agrees. “We are seeing the impact and colour of gravure, but offering the turnaround of flexo. Some of our customers are used to waiting three months for gravure cylinders; our flexo print customers can respond within a matter of weeks or even days. Artwork changes for size, ingredients, or marketing repositioning are more often in this challenged economy, and so the benefits of flexo come to the fore.”
“Our customers are now able to achieve higher densities, higher line screens, and smoother highlights. The look and feel is much more sophisticated, it has generated a lot of interest and orders” says Dave. “We were able to reduce the number of colours within a project in one instance from 8 to 5, because we did not need to separate tone work from solids, and the higher densities meant special colours were not required. That means only five plates, reduced mounting time and material, reduced setup time, and a simpler print job. These are key advances within a competitive market.”
“We are calling our approach ‘HD Plus,’” says Wayne Peachey, Business Development Director at SGS International. “It is not a single solution; it is the application of the right solution for our customer depending on their needs. This right solution will include flat-topped dots, high resolution, solid screening, and special highlight treatments, but we are not limited by one plate type or one technology and so we can find the solution that will work best for our customer.
“Key to our approach is that we will always offer the best solution, leave the ROI to us!”
About the Author:
Wayne Peachey has worked within the graphics industry for over 20 years in technical and business management roles, spending the last 13 in Canada before recently returning to the UK. He can be reached at Wayne.firstname.lastname@example.org