ThinkDon is our periodic Question and answer forum with expertise in the world of large format package printing by our VP of Manufacturing, Don Ellis.

ThinkDon - From Huston Patterson Printers

ThinkDon is our periodic Question and answer forum with expertise in the world of large format package printing by our VP of Manufacturing, Don Ellis.

What factors do we need to take into consideration when designing the coating layer for a printed sheet that will be applied or laminated to a corrugated structure and what are the benefits and drawbacks of leaving areas of the printed sheet uncoated?

When evaluation a project there are three basic areas to consider regarding coating on a printed sheet:

  1. Will the box or display glue in an area covered by the printed sheet?
  2. Will there be another item, such as a tear-off pad, glued to the printed sheet?
  3. Will there be a time-stamp or other information printed on the printed sheet after the initial printing?
Each of the above scenarios generally requires an absence of coating in those areas for proper adhesion.  The absence of a surface coating allows the adhesive to dive into the sheet.  In the case of imprinting information most printers require a more absorbent area for proper drying.

There are some adhesives that will work well over coating.  These adhesives should be thoroughly tested with printed samples prior to the job being printed.  

The most common down side to not coating an area occurs when ink is still printed in that location.  The ink loses the protection of the coating and will frequently cause a longer drying time before it can be handled.  

Labels: , , , , , , ,

What effect does the environment have on litho labels?

Wood and wood related products (litho labels) change as their surrounding environment changes. Paper is made from wood pulp, which begins the paper making process at about 90% water. The relative humidity (moisture) in the air causes paper fibers to expand (higher humidity) or shrink (lower humidity). This change is generally more noticeable around the fibers (diameter) rather than in the length of the fibers. Huston Patterson's experience indicates that low humidity generally presents more of an issue with lithe labels and corrugation then periods of high humidity. Some of these issues include tunneling, cracking-fracturing, and shrinkage.

Tunneling: Although there are multiple factors that may cause a litho label to tunnel when applied to corrugation, the most common cause is the litho label has a lower RH (moisture content) than the corrugation. This lower RH generally occurs during dry environmental conditions, either because outside air is dry, or the air inside a facility becomes dry because we heat it and do not replace the lost moisture. Regardless of the cause, this change in moisture from the originally manufactured environment causes the fibers in the label to become dry and shrink. When we apply adhesive (moisture) to the lithe label, too much of the moisture in relation to the corrugation is absorbed by the litho label causing an over expansion of the fibers. As the adhesive dries, the fibers continue to expand causing the tunneling.

Cracking-Fracturing: There are many factors that may cause cracking or fracturing on a corrugated box or display. Once again, one of those is a low RH or moisture content of the litho label and/or corrugation. I believe the concept that something dry is more brittle and less pliable than something wet is easily understood.

Shrinkage: The one single issue that is extremely tough to understand is how the size of a litho label may shrink between the time it is cut and later inspected. This change in size is more often noticed across the grain of the sheet (diameter of the fiber), rather than the long grain dimension of the sheet. This size change occurs in low humidity conditions which cause the fibers of the sheet to shrink as they lose moisture. We see the most dramatic changes in single sheets that are exposed individually to the environment.

Labels: , , , , , , ,

In your experience, what areas of concern do we need to consider when using metallic inks?

There are several things to keep in mind regarding this type of ink. Metallic ink contains metallic particles that rise to the surface of the ink during the drying process. These metallic particles reflect light and create the metallic appearance. Common metals used to manufacture metallic ink include aluminum, copper, bronze or zinc.
  1. To achieve the full effect of a metallic appearance, designers should avoid using metallic ink in small type, thin lines or areas with less than 50% screening. A small amount of coverage simply does not allow enough of the metal to rise to the surface and reflect enough light to appear metallic.
  2. Metallic ink is opaque and generally is not printed over other inks.
  3. Metallic ink should be printed on coated stock. Uncoated stock allows the ink to absorb into the stock and less of the metal to rise to the surface.
  4. Metallic ink is more expensive than conventional ink, and requires slightly longer make ready and wash-up time on press.
  5. Metallic inks are available in numerous colors as well as the traditional silver and gold metallic colors.
  6. It is also possible to print Metallic Silver or Metallic Gold as a base and then print process ink, which is transparent, over the metallic ink to achieve a wider range of metallic appearing colors.(commonly referred to as MetalFX Ink Technology)

What file types can your pre-press department work with, which do they prefer, and what are the most common issues with clients’ files?

Our experience suggests that some file types work more smoothly than others and are more user-friendly, should a correction be needed on the current or future printing.

Based on our experience, we recommend the following:
  1. Illustrator – type outlined, fonts & images included. Images should be 300 dpi or above.
  2. InDesign – type outlined, fonts & images included. Images should be 300 dpi or above.
  3. High Resolution PDF – fonts & images included. Images should be 300 dpi or above.
The most common issues are missing fonts and missing or low resolution images.

There are many fonts available to designers, some have the same name but are slightly different. For example, the kerning (space between letters) may be different, or the weight or style of letters may be slightly different.

To ensure that the correct fonts are available, it is always best to supply them with the file. Failure to do so may result in an unexpected change or an inability to properly correct a file.

A low resolution image will print. However, the quality of the reproduction may be severely limited. One thing to keep in mind is that when an image is enlarged the resolution will be decreased.

We have been experiencing a lot of cracking when folding our litho laminated boxes. What are some of the possible causes?

There are numerous factors that contribute to excessive cracking of litho laminated boxes. Some of those causes are:
  1. The litho label and corrugation have become too dry causing the fibers to break rather than bend around the fold. The loss of moisture could happen at the time of production or during storage, especially during the dry winter months.
  2. The die may be worn down or not designed properly for the mechanical process being used to die-cut the product. A die maker may be able to suggest a different width, depth or style of score that will facilitate a better fold on a particular piece.
  3. The amount of recycled fiber and the number of times paper stock has been recycled to manufacture corrugation continues to increase. The repeated recycling will continue to shorten the fibers causing them to fracture rather than be long enough to bend around a fold.
  4. The ink film thickness on a score or fold will make cracking more visible. Sometimes, it is possible to either re-design the graphics or change the ink percentages to achieve the same color but with a lower ink film thickness.

I understand that Huston Patterson recently installed a large format digital flatbed UV press. What are its capabilities and how can I utilize it to better serve my clients?

Yes, Huston Patterson has installed a Gandy Pred8tor flatbed UV press. The maximum sheet size of the Pred8tor is 48” x 96” on material up to two inches thick. With a 6 picoliter dot size, the reproduction is very good. Color is managed by GMG software and the Pred8tor is calibrated to G7 standards on a variety of substrates.

We installed the Pred8tor to enhance the services we offer our clients. The digital press can be a lower cost alternative for short run POP displays allowing a manufacturer to test a product in a small number of locations.

Another possible use is to utilize the Pred8tor to reprint small quantities of litho labels or top sheets to fill an order that was short. We offer all substrates we normally print on, as well as a selection of litho labels, SBS and Kalima, pre-mounted to B and E flutes.

Huston Patterson looks forward to meeting your digital print requirements. Please contact your Client Services Manager for samples and further information.

As a G7 Master Printer Certified, what steps were taken to certify your presses?

  1. Linear (no curves applied) plates were made of an approved color test form. The test form includes a G7 press target that contains 275 individual gray of color squares.
  2. Proper ink densities for each color are established on a press that meet the appropriate ISO standards.
  3. Ink and water is balanced across the sheet and 2,000 sheets are run to simulate a normal press run.
  4. Sample sheets are removed from the run.
  5. The G7 press targets are read by the Isis color spectrophotometer.
  6. The spectro readings are then evaluated and curves are established for the individual colors to conform to the G7 standards.
  7. The G7 color test for is then plated with the applicable curves (a curve changes the dot size going to the plate so the printed image meets the G7 standards) applied to each color.
  8. The color test form is put back on press.
  9. Ink and water balance is achieved to the standard ink densities established earlier.
  10. Sample sheets are removed from this run and spectro data is checked to verify it meets the G7 standards.
  11. Sample sheets and the appropriate documentation is sent out for certification approval.