Archive for the ‘Finishing/Converting’ Category

Rod Coating vs. Flood Coating

August 2, 2017

Geordie asks,

We’re considering some new equipment and looking for some information on flood coating versus rod coating.

If I were looking for new equipment I would probably lean toward rod coating. In my opinion rod coating is more effective and accurate than flood coating. Rod coating provides a very wide coating weight range. They also allow much greater precision in coating weight control and are typically much easier to operate. The rod coating process also provides superior cross machine coating uniformity as compared to flood coating.

Most modern rod coater designs make very easy and quick to change the coating thicknesses as well. So if minimizing changeover time is important to you that may be another advantage to rod coating.

— Ralph

 

Advertisements

GMI Certification for Corrugated Converters

June 15, 2017

John asks,

We recently had a customer ask if we were GMI certified. What do you know about this, how long does it take to receive the certification and do you know any Independents that have GMI certification?

Our associate Scott Miller at BCM Inks helped us with some background and industry knowledge on the subject.

The GMI certification awarded by Graphic Measures International (gmi), a St. Louis Missouri based company that certifies, monitors and measures the performance of packaging suppliers with a main focus on positioning plants to meet graphic standards of quality and color. Global brand owners often require this as a measure to help them maintain a consistent appearance of their brand.  Through training, process development, certification and continual monitoring GMI ensures plants are maintaining and running to industry standards.

The GMI certification process is rather in-depth and can take 3 to 5 weeks. The process measures everything from light booths to actual print samples. Many brand owners who are quality and color critical will only qualify or use printers who are GMI certified. This gives the brand owners the confidence that the printer has process control in place to provide repeatable results that will meet their global standards.

According to Scott he can name any [particular] corrugated printer who is GMI certified. “However, I see their certification stamp on a lot of light booths when I’m in plants.”

 

— Ralph

Moisture Test Comparison MRA vs. non-MRA Box

May 24, 2017

Steve asks,

Would you have or could you please direct me towards any testing data/statistics on a box with MRA vs. a non-MRA box?  I would like to see what kind of improvement it shows in a moisture-related test.

The dimensions, flutes and composition range (very small to large boxes; B/C, E/B, and B flutes; 32ECT to 71ECT), and I don’t have much info on supply chain.  A customer just looking for any testing data that he can get on MRA to demonstrate that it does improve performance in moisture.

For assistance with answering this question I reached out to Clayton Clancy at Kruger. He has provided this this detailed study on stacking performance when using water-resistant adhesives, complied by the Institute of Paper Chemistry, which high-lights paperboard performance improvements when using WRA additives. He cautions that there are varying terminologies used when discussing water resistance such as (MRA, WRA and WPA), with that in mind I hope this will be helpful.

— Ralph

Cracking Litho-lam, Does ‘Sides’ Matter

May 8, 2017

Clint asks,

I have a question that I hope you can answer.  When using the same liner board on both the inside and outside of a singelwall sheet, why do you see more of the “flute lines” on one side versus the other?  What causes that and does it have more effect on fracturing the liners when you are creasing one side versus the other?

This came up when one of my customers was laminating a litho label on SInglewall.  They normally laminate it to the good side (less visible fluted lines).  Because some of the sheets were slightly warped, they laminated some on the bad side (more lines).  After converting there was some fracturing of the litho (not liners).   We saw less fracturing of the litho on the labels that were laminated to the bad side.  From a logical standpoint, if you put the label on the bad side and it is a weaker paper, I think the label may stretch easier versus being glued to a heavier liner.  Also, the inside of the box would look better (less visible flute lines) so I would assume this should be the norm unless you are just spot labeling something.  Keep in mind, the liners on the inner and outer were supposedly the same paper.

What are your thoughts on this?

 

Thank you for an excellent question. Yes, I can add some insight.

Tensile strength and stretch of the liners are impacted differently in the singleface and doubleback operations. Also temperatures and starch application are different in the two operations. Fracturing can occur in one liner and not the other. Learning flutes can have an impact. Microphotographs of the cross section of the combined sheet can begin to reveal some issues.

Of course starch application and amount can signal issues as you described. World class consumption would be about 1.4 # per msf.

– Ralph