Fine papers products are all around you and can be found in almost any home, office or business. These include a very wide variety of paper products for uses such as A4 copy paper and printer paper, book paper, envelopes, forms, writing pads, high-quality magazines and brochures, company magazines, catalogues and annual reports. Fine papers make an important contribution to society whether it be for literature, historical records, business, pleasure or any number of other purposes.
Fine papers are printing and writing papers, which are made of chemical pulpˇ and may also contain recycled fibers. They consist of two different kinds of papers, coated woodfree (CWF) and uncoated woodfree (UWF) grades. CWF grades use UWF (jumbo) reels as the base material, upon which one or more thin mineral coatings are added to smooth the surface and improve printability.
UWF and CWF papers can be further divided into different sub-grades depending on whether the paper is cut into sheets or used in reels. UWF papers include 3 sub-grades: cut-sizes (A3 or smaller, including A4), folio sheets (larger than A3) and reels (rolls). CWF papers are composed of 2 sub-grades: sheets and reels.
Fine papers are all around you in everyday life. The aim of this section is to explain the different end uses of fine paper and discuss which type of products the UWF and CWF sub-grades are used for. The most widespread printing methods are also briefly introduced.
The majority of the UWF cut-size paper is A4, which is used in offices at work and home for printing and copying purposes. UWF cut-size paper can be white or coloured, and it is used both in laser and inkjet printers and in copying machines.
[1] Home office where A4 paper is used
UWF folio sheets are used for printing books, direct mailings and materials for corporate communications. Folio sheets can also be utilised for printing sales promotion materials such as brochures, leaflets and price lists. The majority of folio sheet printing jobs are done with offset printing presses. When printing folio sheets, a sheet-fed offset press is used, which is specially designed for printing sheet-sized paper.
UWF reels are used for producing writing pads, envelopes, books or business forms, for instance. The majority of UWF reels are printed using the offset printing method. While sheet-fed offset presses are used for printing folio sheets, for reel printing jobs there are also special offset printing presses, i.e. web-offset printers, where only reels can be used. Thus the printing process is the same but the method of feeding the paper differs.
[2] Book
CWF sheets are used for printing for instance high quality books, e.g. art books. CWF sheets can also be found in magazines, where either the cover is made of CWF sheets, or the whole magazine can be CWF paper. Furthermore, a significant amount of sales promotion and direct mail material is made of CWF sheets. CWF sheets are also used when producing materials for corporate communications such as annual reports, company magazines, catalogues and brochures. The majority of CWF sheet printing jobs are done with sheet-fed offset presses.
[3] Annual report
CWF reels are used for the same fine paper products as CWF sheets. The decision whether to print on CWF reels or CWF sheets is an economic one. When the print run is long, it is more affordable to print CWF reels, whereas for small circulations it is more economical to use CWF sheets. The most widely used printing method for CWF reels is web-offset printing, with the majority of the CWF reel printing done using a special process called the heat-set offset˛ printing method. As opposed to standard web-offset printing where the air dries the ink, in heat-set offset printing the thermal heat of a dryer unit rapidly dries the ink.
[4] Company magazine
ˇ Chemical pulp has been processed by cooking wood chips with various chemicals at high temperature and pressure.
Offset printing is based on the principle that oil and water do not mix. In offset printing first a water roller and an ink roller are in contact with a plate cylinder, which includes the image area. As a result, the oil-based ink sticks to the image area. After that the plate cylinder transfers the ink and the water to a rubber cylinder, which in turn transfers the image on to the surface of the paper.
˛ A heat-set offset printing press includes a dryer unit, which evaporates the ink. After that the paper goes through a series of chilled rolls, which cool the paper and set the ink. For heatset printing CWF paper needs to have sufficient quality to allow it to withstand the heat, which can be up to 100°C. A standard offset printing press can usually only print on one side of paper at a time. Heat-set offset web presses normally print on both sides of paper at the same time.
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