Do you know what’s behind a printing blanket?

behind_printing_blanket
Printing blanket is a key element for any offset printing press, its characteristic impacts the printing press performance and the final print quality results.

As well as a vehicle needs a proper tire to drive fast, far, and safe, a printing press requires a proper printing blanket to run smoothly and to provide quality and consistency.

Printing blanket is a very high complex composite material, a mix of several layers of polymers and fabrics.

Different polymers are used to give specific chemical or mechanical properties. There are layers meant to give specific bonding properties and layers with very strong chemical or mechanical characteristic.

During the manufacturing process, the grinding is one of the final and key steps to provide a printing blanket with a smooth and uniform surface. The grinding process is needed to achieve the very narrow thickness tolerances which is needed by modern and fastest printing presses.

The most common thickness specifications are:

  • 1.96 +/- 0.02 mm
  • 1.70 +/-0.02 mm

Once the blanket is installed and the plate is mounted, the printing process can start.

A proper indentation is needed to ensure the correct ink transfer and reproduction of the image. A blanket will have to perfectly transfer the image from the printing plate to the substrate, for doing that the blanket surface should be very uniform and consistent. 

There are blankets specifically designed for each printing segment: commercial sheetfed, packaging UV printing, metal decorating, web printing, business forms, and many others.

This is because each printing segment have specific needs and requirements

Some blankets are designed in 4 ply, 3 ply or 2 ply structure, the choice depends on the specific needs of the segment but also by the specific needs of each printing press.

Some offset printers prefer a very soft and compressible blankets while some other prefer a very robust and mechanically strong structure in 4 ply.

Coating and varnishing

Coating is done to provide value to the final printing, it therefore requires a proper and specific product. A printer can use a varnishing blanket or a coating plate. One of the benefits of using coating plate is also the possibility to do spot coating, which is more and more demanding and requested by the market.

Varnish blanket has a structure that is similar to other offset printing blankets, usually have a very smoot surface and a structure made of fabrics which are cut and peel off for the knockout of the spot coating

During the past few years, the packaging market has seen the expansion of coating plates which have a polyester base allowing mechanical stability and are made without fabrics, then allow a very easy peel off and no fabrics pattern

The printing blankets and coating plates are not only consumables but an essential part of every offset printing press. Only with a proper selection of the most suitable product offset printers achieve exactly the right quality they need.

For more information email to printingsm@trelleborg.com