The Hindu case-study: An approach to 42 gsm

The Indian newspaper industry has adapted to 45gsm newsprint. Mohanraj P, AGM production, The Hindu, said, "Reduction in grammages is the need of the newspaper industry to contain the cost of production. Nearly 6% of the total production cost can be curtailed by this."

 

But a reduction in the grammages comes with challenges in terms to retain quality and production capabilities. The Hindu first started trials for using 42 gsm in the year 2012. After a series of trial and error, the newspaper completely shifted to using 42 gsm by 2014 in all its production units.

 

Mohanraj said, "The 42 gsm paper came with its constraints in terms of printability and runnability. There are different demands on newsprint paper properties for heatset and coldset machines, with the change in the grammage properties such as tensile strength, tear strength, thickness and porosity changes. For example, in 42 gsm newsprint the tear strength reduced by 10% and opacity of the paper reduced by 1.5%."

 

Such change in properties result in web breaks, registration variation, wrinkles in the web and can also lead to shrinkages. Few of the measures taken by The Hindu for web breaks were by ensuring an optimal web tension which minimises the runability issue. Also, problems of the show-through at their press were combatted by redefining the settings at the pre-press level. For example, by reducing the total coverage area from 240 to 220.

 

The press is currently using the AM type of screening. This screening is used as it provides better resolution and working flexibility at the pre-press level plus a smoother tone of print.

 

Few key pointers and checklist were provided by Mohanraj. He said, “One should be aware of the properties and issues with lower grammage and reduce tension for better runnability. Plus use brighter and bulkier paper for top sheets for coldset for better reproduction, use less opaque, good strength and smoother papers in a heatset machine,” concluded Mohanraj.