Processes + Stock

Cont

ents

Con

tent

s

LithographyGravureScreen PrintFlexographyDigital PrintPad Printing + Six ColourFoil BlockingEmbossing/Debossing + Spot/ UV VarnishWeight + FinishLaid paper + Wove paper

ContentsC

onte

nts

1-23-45-67-8

9-1011-1213-1415-1617-1819-20

1

LithographyLith

ogra

phy

Lithographic (offset) printing utilizes the principle that water and grease do not mix. The image area of the plate is treated with a greasy medium. Then the plate is dampened with by rollers then inked. The ink adheres to the greasy image but not the dampened areas. The paper is moved into position over the plate and then the plate and paper are run through the press.

Lithographic has a planographic (flat). The whole surface has both ink and water with the addition of alcohol to aid dispersion.

Lithography first used smooth stone slabs to get a printing surface and this method is still used today for limited editions of fine art prints. The next development in printing came with metal plates which could be curved around metal cylinders to allow the use of rotary press. Finally the “offset” principle was developed.

Where Lithography is used, it is nearly always as Offset. Meaning the inked image on the metal plate is offset (printed) onto a rubber blanket wrapped around a rotating metal cylinder. The image is then transferred from that blanket onto the paper. The reason for the rubber plate is because it is less abrasive to the plate then paper.

2

LithographyLith

ogra

phy

Advantages 1. Good reproduction of detail and photographs2. Cheap printing surface3. Fast make-ready4. Rubber blanket enables the use of a wide range of papers

Disadvantages1. Colour variation due to problems with ink/water2. Dampening can cause paper stretch or warping

after binding3. Dense ink coverage dif-

ficult to achieve4. Fixed cut-off of web-offset restricts available

DAMPENINGROLLERS

INKING ROLLERS

PLATECYLINDER

OFFSETCYLINDER

IMPRESSIONCYLINDER

STOCK

3

GravureGrav

ure

“50,000impressions perhour”

Gravure is a modern day version of the intaglio process. This means that the printing image is recessed (indentation) into the cylinder with tiny hollows on a copper-plated plate cylinder. The indentation vary in depth so they will leave a required amount of ink on the various parts of the printed image. The non-image area is wiped free of ink with a doctor blade. Ink is then deposited on the paper from the indentations.

The ink is very thin and being spirit based dries through evaporation in a heated tunnel immediately after being printed.

Most Gravure is done with web-feed machines. Running speeds of up to 50,000 impressions per hour. Typical jobs generally include magazines or catalogs - very large runs. Printing is from a cylinder rather then a plate which allows speed. Gravure is also used for some kinds of packaging, printing on cellophane, decorative laminates and wallpaper.

4

GravureGrav

ure

FORM CYLINDER

BLADE

INK TRAY

PRINTING CYLINDERImpression roller

Advantages1. Simple printing method and press mechanism2. Can maintain consistent colour3. High speed4. Straightforward drying by evaporation5. Good results obtainable on cheaper paper

“50,000impressions perhour”

Disadvantages1. High cost of cylinders

2. Viable only for long runs 150,000+

3. Longer lead times than offset

4. High costs of proofs, if press proofs needed

5. High cost of corrections for reprints, as cylinder

5

Screen ScreenPrint

Print

What is a line? Oldboy printsOUGD404

6

A synthetic fibre which used to be silk hence the name ‘silk screen’ is stretched across a wooded or metal frame.

The fibre is covered with a UV sensitive paint/ink which is left to dried in a dark room or somewhere out of the way of UV light. A stencil/artwork can then be placed onto the screen on top on the UV sensitive fibre. The screen along with the artwork placed in a UV light box and ‘exposed’. Exposing the frame allows the UV sensitive ink to

ScreenScreenPrint

Printbecome delicate where is has been exposed to UV light. When rinsed with a hose or jet wash crumbles off the frame leaving the UV paint which was hidden by the artwork/stencil.

Ink is then placed onto the frame and pushed through the fibre onto paper using a squeegee. The paper is laid onto a flat vacuum table. The vacuum holds the paper still. The frame can be placed directly onto the paper or it can be fixed into a set position using a holding which is fitted to the ‘bed’

Advantages

1. Can print a heavy fi

lm of

ink2. E

conomical for short runs

(Even below

100 copies)3. C

an print on virtually any m

aterials

Disadvantages

1. Diffi

cult to achieve fine

detail2. V

ery low screen halftone

3. Low

output qualities4. D

rying requirements

FlexographyFlex

ogra

phy

7

“Engraved etchings that hold the ink”

IMPRESSIONCYLINDER

PLATECYLINDER

ANILOXROLLER

PRINTINGCYLINDER

FOUNTAINROLLER

INK

DOCTORBLADE

STOCK

on cellophane,

plastics and

metallic

foils. It

is generally

used to

produce som

e of

the cheaper

magazines

and

newspapers.

A

good proportion

of new

spapers are

printed using

this m

ethod as

the inks

doesn’t suff

er the

balance of

water

and ink. T

he ink

dries instantly

and doesn’t

come

off on

the hands

of the newspaper reader.

This m

ethod of printing is ideal for short runs of prints, colour and black and w

hite work. U

nlike m

ost other

printing techniques

it doesn’t

require film

or a plate to be m

ade which m

akes the start up process cheaper. A

lthough the

start up

cost is cheaper the cost per print is higher then off

set litho.

FlexographyFlex

ogra

phy

8

IMPRESSIONCYLINDER

PLATECYLINDER

ANILOXROLLER

PRINTINGCYLINDER

FOUNTAINROLLER

INK

DOCTORBLADE

STOCK

Flexography is

the process

that is

a derivative of letterpress, using

flexible photo

polymer plates and thin,

fluid inks

(often now

w

ater-based rather than spirit-based) that dry by evaporation

(sometim

es assisted

by heat)

The

image is raised as in the

conventional form

of

letterpress printing.

Most

flexographic printing presses are w

eb-fed because of the nature of

the products

they are

usually em

ployed to

print. Ink

is applied

to a

plate by

a m

etal roller;

"anilox" roller,

this roller has engraved etchings

that hold

the ink and transfer it onto the

flexible plate

for printing. M

any machines

are multi colour presses,

for four-colour work.

Mainly

used for

packaging printing

9

Digital PrintDigi

tal P

rint

This m

ethod of printing is ideal for short runs of prints, colour and black and

white

work.

Unlike

most

other printing techniques it doesn't require film

or a plate to be made w

hich makes

the start

up process

cheaper. A

lthough the

start up cost is cheaper the

cost per

print is

higher then offset litho.

Digital printing uses files such as PSD

, JPE

G etc transferring the im

age digitally to the printer, this technique of print-ing

has allow

ed both

ultra-short run

reprinting and

"print on

demand"-

Exam

ple w

ould be

offset litho

needs a minim

um run of

around 500 in order to be econom

ical.

With

digital printing

the publishers

can produce order of one print which

can be printed quickly. Digital print

quality is general inferior to offet-litho especially w

hen the job has large areas of flat tints or solid colours. H

owever

this is rapidly changing as technology is constantly m

oving forward fast and the

price of digital print is reducing.

10

Digital PrintDigi

tal P

rint

Advantages

1. Econom

ical for short runs (500 or less)2. E

nables personalization of data3.N

o film or plate cost

4. Shorter lead time

5. Large formats possible w

ith ink-jet printing

Disadvantages

1. Quality of som

e digital printers is inferior to offset.2. C

onsumerables (toner/paper)

11

Pad PrintingPa

d Pr

intin

g

SOLVENTSEVAPORATEFROM THE INK

PAD PICKS UPTACKY SURFACEOF INK

PAD DEPOSITSTACKY INK ONTOSUBSTRATE

SOLVENTSEVAPORATEFROM THE INK AS THE PADMOVES TO THEPRINTPOSITION

Pad printing is a printing process that can transfer a 2-D image onto a 3-D object. This is accomplished using an indirect offset (gravure) printing process that involves an image being transferred from the solid plate via a silicone pad onto a substrate (stock/material).

Pad printing is used for printing on otherwise impossible products in many industries including medical, automotive, promotional, apparel, and electronic objects, as well as appliances, sports equipment and toys. It can also be used to deposit functional materials such as conductive inks, adhesives, dyes and lubricants.

12

Hexachrome is an ultra-high fidelity six-color process printing system developed by Pantone, Inc.

Hexachrome adds orange and green to the traditional CMYK inks for a larger and more vibrant gamut, or color range. However, such alternate colour systems still rely on color separation, half toning and lithography to produce printed images. Accurately reproducing a wide range of both vibrant and subtle colors that can be defined and displayed on computer monitors which previously could not be duplicated in print.

Six ColourSi

x Co

lour

13

Foil BlockingFoil

Bloc

king

Foil blocking, oil stamping, hot

stamping, foil im-printing & leaf imprinting.

Foil blocking also called foil stamping, hot stamping, foil imprinting and leaf imprinting - uses a heated die strike to apply a colored, clear, metallic, matte, pearlescent, holographic, or otherwise tinted foil to another surface. Foils can be opaque or semitransparent. The process can be combined with embossing for a dimensional effect; applied on top of flat printed graphics for a bit of shine or extra emphasis; or used alone to create its own effect.

The stamping process is a mechanical one- a heated die imposes the foil onto the printing surface. Registration can be a bit off from hit to hit. Type sizes should stay above 8 point and lines should be no thinner than 2 points. Foils tend to fill in tight areas, such as tightly kerned type or lines that are closely spaced; generally a good idea to use in more open areas.

Smooth, coated stocks work best for foil stamping. Uncoated or textured surfaces present an irregular surface that may disrupt and break up the foil. Large areas of stamping can bubble on highly coated stock if the chemistry between the two layers is not carefully considered. Also foil blocking on top of coatings or inks with high wax levels will also cause the foil to adhere improperly. Aqueous and other wax-free coatings are the best for using underneath foils; ask an experienced foil stamp supplier for guidance on getting the most effective results.

Some foils can scratch easily, especially in large flat areas, so make sure the clients are aware the stamped surface could become marred with use.

Foil blocking, oil stamping, hot

stamping, foil im-printing & leaf imprinting.

Foil

Bloc

king

Foil Blocking

14

15

Embossing/DebossingEmbo

ssin

g/De

boss

ing

Em

bossing/debossing and

de-bossing takes

printing into a third dim

ension. Paper is pressed betw

een two m

olds called

a die,

that sculpt

its fibers by as m

uch as 1/8 of an inch. Im

ages higher than the rest of the paper are em

bossed; im

ages lower are de-bossed.

Both

are produced

under heat to assure fine detail.

Heat also m

akes the images

smooth and shiny. E

mbossed

impressions

made

without

having to

register over

a previously printed im

age are said

to be

blind em

bossed. B

lind im

pressions cost

less then

impressions

over ink

because press operators don't have to register dies precisely.

Dies

are m

ade from

either

magnesium

or brass.

You should

not try

to use

lines that

are so

fine that

paper doesn’t press into them.

Deep dies need beveled edges

to avoid

cutting the

paper. A

nd beveled edges optically reduce the size of the im

ages, so

prepare the

original artw

ork slightly over sized.

16

Spot/UV VarhishSp

ot/U

V Va

rnis

h

Spot

/UV

var

nish

is

a cl

ear

liqui

d th

at

is ap

plie

d lik

e in

k an

d cu

red

inst

antly

with

ul

trav

iole

t lig

ht. I

t can

pro

vide

ei

ther

a g

loss

or

mat

t co

atin

g.

Incr

easin

gly,

UV

va

rnish

is

used

as

a po

t co

veri

ng t

o hi

ghlig

ht a

par

ticul

ar i

mag

e be

caus

e it

prov

ides

m

ore

shin

e th

an v

arni

sh.

The

va

rnish

is

appl

ied

to

high

light

disc

rete

are

as o

f a

prin

ted

desig

n, b

oth

visu

ally

an

d by

im

part

ing

a di

ffere

nt

text

ure.

The

eff

ect

of

spot

U

V c

an b

e m

axim

ised

whe

n ap

plie

d ov

er M

att-

lam

inta

ted

prin

ting.

WeightWei

ght

Weight (gsm)

Paper is mostly defined by its weight using gsm (grams per square meter) or g/m2; This is called grammage.

Photocopier papers are usually around 80 gsm; letterheads and pamphlets, around 110 gsm and posters, around 170 gsm; lightweight covers.

17

18

FinishFini

sh

Commercial printers commonly distinguish between coated and uncoated paper.

Coated paper can be further devided into additional categories depending on the amount of coating it has: lightly coated, medium coated, highly coated or art paper. Coated paper has a smoother surface which gives it a higher printing quality. Examples include brochures and high culture magazine covers. Examples of uncoated papers include stationary, photocopying and pages of paper back books.

“Uncoated paper is not necessarily cheaper than coated.”The surface of the paper can be calendered to obtain a higher sheen. A coated paper can be matte or glossy. Uncoated paper can be calendered.

A glossy paper gives a good reproduction of image and colour, while text readability is poor because of distracting reflections. Matte and/or uncoated paper is generally more suitible for readability, the texture is smooth but non-reflective, which means that the paper is treated with this coating will produce prints with a combination of high image quality and readability.

finish: gloss/silk/matt, coated or uncoated

19

Laid PaperLaid

Pap

er

This page is printed on Laid paper!

There are basically two types of paper - wove and laid. A wove paper is produced on a closely woven mold or screen and shows no impression from the mesh of the screen.

20

Wove PaperWov

e Pa

per

This page is printed on Wove paper!

A laid paper is produced on a coarser screen or mold supported by wires which unlike wove paper is textured.