Monday, 18 November 2013

Paper/ Stock

Paper Formats 

A Series 
(The preferred series)(out of A and B)
The ISO/DIN standard (ISO International Organisation for Standardisation) (DIN the German Institution for standardisation) 
Both accepted by almost all countries 
(usually, the only differences are the permitted tolerances) (and some countries still retain traditional methods, most of them less systematic and non-metric) 

The reference format for the A series is A0 
with an area of a square metre (1m² 
the shorter side of the sheet is in a ratio of 1 to root 2 (1.414... ) 
each format is twice or half as large as the next format in the series

the A and B series are usually final formats

there are also untrimmed and oversized formats 
these are larger 
they are not trimmed to A series format until after, printing, binding

Paper forms 
Can be supplied by the manufacturer or the wholesale trade in reel or sheet form
1. Reel
2. Sheet

Formatted paper is cut to the size required in the paper factory , and then packed 
Usually in a size optimised for a particular print format 
This reduces cutting waste 
And as paper prices are usually calculated by weight, this can reduce paper costs

The raw material for paper is pulp 
Made up of cellulose fibres derived chemically or mechanically from vegetable raw materials, particularly wood

Paper Finishing
improves surface smoothness, gloss, whiteness and printability 
coating colour used for this consists of natural pigments, a binder and various additives

(also called Santinising) 
smoothing the surface in the calendar makes the surface glossier, the so called ironing effect
calendars are specialist machines 
they consist of a system of cast steel and paper rollers
paper passes through them in a snake configuration 
the polished steel rollers perform the actual smoothing function

The quality of the paper surface is very important if paper is intended for printing. 
It is also very stimulating in visual or tactile terms
The paper characteristics need to be right for the intended printing process 
e.g. papers intended for web printing on rotary presses must be particularly tear-resistant

Colour Printing requires high dimensional stability
the paper must not stretch in printing, as the colours can't otherwise be printed on top of each other precisely

Picking Resistance 
of paper indicates how much force has to be exerted by vertical tension to detach particles from the surface
particularly important in offset printing

Ash Content 
identifies the proportion of inorganic substances that remain behind as ash when the paper is burned

The direction - Grain - of the paper is the lie of fibres in the paper
derived from the manufacturing process
this means that the paper has two different qualities relating to different directions in which the paper runs through the machine
the fibres lie in a particular direction in relation to the flow of the wet paper pulp 

In the case of books or brochures with several pages,
the grain of the paper should run parallel to the gutter
otherwise the moisture in the size would cause the paper to swell and become wavy at the gutter 
it would affect its aesthetic appeal and the handling of the book etc themselves

Sheets can also be cut in narrow web (also long grain) 
or wide web (short grain)
narrow web the paper fibres run parallel with the long side of the sheet 
for wide web they run parallel with the shorter, narrow side

Always specify the width first, then the height when giving dimensions
to avoid misunderstandings 
it is also customary to specify the terms landscape or portrait to the dimensions

There are various Test Methods that can be used to determine the grain of the paper

Tearing Test:
a piece of paper is torn lengthways and widthways- 
the paper will tear more easily and in straighter lines parallel with the grain

Fingernail Test:
both sides of a sheet of paper are drawn through the thumb and the middle fingernail-
if the edge of paper remains smooth, it is parallel with the grain; it appears wavy across the grain

Moisture Test: 
the paper is moistened along its length and width-
parallel with the grain the paper rolls up, across the grain it appears wavy 

Bending Test: 
the paper is bent-
the paper offers less resistance parallel with the grain 
(advantage of this method is the paper is not damaged)

Paper Weight
the weight of paper is measured per unit of area (or area weight)
in grams per square metre (g/m² 
Paper grammages range from 7 to about 225 grams per square metre
commonest paper weights 

Lightweight printing papers approx. 40g/m²
Newsprint approx. 50g/m²
Poster Papers approx. 60g/m²
Art Papers 90 to 135g/m²

it is not unusual for the weight of the paper to be erroneously equated with paper thickness
papers of the same weight can have different thicknesses 
the relationship between the paper thickness and paper weight is defined as volume

Paper Types

Coated and Uncoated
coated paper types have been coated with a substance containing a pigment on one or both sides 
coated papers can be further categorised
e.g.LWC papers- lightweight coated papers

Art Papers
coated elaborately, for prestigious colour printing 
usually an even smooth surface
they are available with matt, semi-matt and glossy qualities 
pictures of the highest halftone grades can be reproduced in letterpress or offset

Illustration printing papers 
are coated 
often calendared
and available in various qualities
often used to replace more expensive art papers

Cast-Coated Papers
(and cards) 
are especially glossy 
however not produced by calendering but by rolling the damp or dampened printing substrate with a highly polished chromium-plated drying cylinder

Board and Cardboard

around 225g/m²
while board always has a finished surface and consists of high quality materials
cardboard is made with lower-quality raw materials
Board has a grammage between paper and cardboard 
it is made with the same raw materials and additives as paper
when working with board and cardboard it cannot be precisely defined by weight, attention has to be paid to the grain
pasteboard- is used most frequently 
weights given in millimetres
hardboard- a solid, dense surface and is particularly suitable for large areas of embossing on book covers 
weights given in kilo grammes

Special Papers
Parchment/ greaseproof paper- is boil resistant, fat and waterproof paper, an impermeable surface.
Carbon-copy paper- a thin 30-40g/m², machine finished typing paper, usually wood free.
Carbon papers- consist of a substrate with carbon ink that conveys the impression of the next sheet when printing.
WP papers- made of 100% waste paper
Fine papers- usually the best quality papers, particular attention is paid to the firmness of the surface in manufacture.
Medium fine papers- have over 5% mechanically recovered wood fibres (mechanical pulp).
High Gloss papers- are cast-coated on one side.
Chromium Papers- are wood-containg or wood free, papers coated on one side, coating is always water tight, and is formulated with a view to making the paper highly suitable for offset printing, as well as stamping, varnishing and bronzing, used for many labels
Coloured papers- are tinted, varnished and patterned papers, velour, bronzed or marbled papers. 
Vat papers- handmade papers drawn from the 'vat' with a sieve, typically uneven edge, machine-made imitations of this paper are now available
Japan papers- also called 'washi' (wa=japan and shi=paper) are made with native Japanese plants such as kozo, mitsumata, gampi and kuwakawa.

Papers by Use
Bulky papers- also called voluminous papers, soft, elastic papers, thin papers also called India or Bible papers, are low grammage papers made of rags and bleached pulp and with great strength.
Offset papers- are wood free and wood-containing uncoated papers as well as uncoated recycled papers in calendered or machine finishes, well suited for offset printing.
Magazine papers- also art papers, are uncoated, usually wood-containing, calendered papers with a high proportion of filler that are particularly good for reproducing pictures, above all other papers used for gravure-printed magazines
Laser Printing papers- have an even, specially prepared surface to ensure the best toner adhesion and to support the instant electrical discharge in the printer.
Inkjet papers- surfaces finished for rapid absorption of the ink that an inkjet printer bombards the paper with at high frequency in tiny droplets in an inkjet printer, they help prevent the ink from running.
Poster papers- for large-format posters, usually wood-containing and heavily sized, these papers are uncoated with special properties that allow them to soften before being posted, particularly weatherproof and water resistant, which are highly tear resistant even when wet.
LWC papers- high quality, thin, coated papers used mainly in web offset printing and in gravure printing for magazines and catalogues.

Electronic Papers
one variant has tiny spheres with different colours on different sides, these turn with the aid of electrical fields, and thus make it possible to see different colours.
another contains small transparent capsules filled with dye and white particles, when an electric  field is created, these particles float upwards and make the surface of the paper look white, at other times the dye predominates. 

The Little Know-It-All, Common Sense for Graphic Designers- Die Gestalten Verlag, Berlin 2007

GF Smith
Gmund Paper
International Paper
M-real Zanders
Scheufelen Papierfabrik 

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