The paper you choose for your folded print piece is one of the most important factors in the folding process. We caught up with Pekka Korhonen, Head of Technical Customer Service at Oulu mill, to talk about the folding properties of Lumi papers. So what makes Lumi excel in folding?
“The composition of the pulp used, the structure of the paper and its coating are important properties contributing to the excellent folding properties of Lumi papers, but the secret is really our expertise and know-how. We do regular benchmark tests with our customer in which we test both the inner fold and outer folds. Our customers make the ratings together with our printing lab. I believe we are unique in doing this kind of benchmarking”, says Pekka.
“We have several customers who choose Lumi papers especially for their folding properties. They appreciate that their printed pieces are void of dusting on the inner fold or cracking on the outer fold. I do recommend pre-creasing before folding for sheets above 170 gsm.“
Oulu mill's printing laboratory testing folding. Left to right: Minna Greus, Minna Huhtala, Anni Tuovinen ja Annukka Kieloaho.
We asked Visa Koskinen, Production Manager at Grano, one of the biggest printers in Finland, why good folding makes a difference. Read about his thoughts:
Why are good folding properties so critical?
“Good folding properties are most important because they greatly affect the speed you can run your paper in folding machine; the difference can easily be 4x faster on good paper vs paper with bad folding properties.”
Can you quantify the amount of paper waste if the folding properties are not good enough?
“If paper has really bad folding properties the waste amount can go from 1-2% on good paper to 15-25% of waste on bad papers and the run time for folding can go up to 10x due to constant machine stoppings.”
What is your opinion about Lumi with respect to folding?
“Lumi has good properties in folding, most substances can be folded in maximum speeds depending on the type of folding. From 90g to 115g you might want to have grain direction against the folding and for 170g and higher grammages you need creasing to ensure smooth running and good quality.”