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66 FLEXOGRAPHY: PRINCIPLES & PRACTICES

(e.g., white or yellow). In addition to

light backgrounds, “reddish” colors may

also be used.

4. In many cases the symbol background is

not printed. It is the color of the substrate

being printed (see Substrate Significance

below). If the symbol background is

printed beneath the bars, the background

should be printed as a solid color or in

multiple layers of solid color coverage to

increase the background opacity.

In many cases the designer can be

involved in the specification of the printing

material characteristics such as matte, gloss,

color or texture. The printer may submit

sample materials for evaluation and/or

approval. Whenever these decisions are

made, it is important to consider the effect

on the scannability of the bar codes. Such

considerations as how an overprinted var-

nish or laminate will affect the symbol, as

well as how the use of fluorescent, metallic,

transparent or translucent materials might

reduce the symbol contrast of the bar code,

should be a priority.

SUBSTRATE SIGNIFICANCE

Some bar code symbols, such as Inter-

leaved 2-of-5 (ITF), are typically printed

directly on linerboard. Because of a lack of

contrast, symbols printed on substrates such

as natural kraft linerboard are more difficult

to scan than symbols printed on mottled

white linerboard, full bleached linerboard or

white paper labels. For this reason, the best

scanning results are often achieved by print-

ing bars with opaque black, dark blue or dark

green inks with uniform coverage. Table 12

lists the Fibre Box Association’s recom-

mended Edition VIII GCMI colors for ITF

symbols on natural kraft substrates.

LOCATION, LOCATION, LOCATION

There are actually two primary considera-

tions when determining symbol location.

The first is the symbol placement on the

design and the second is the symbol orienta-

tion (rotation) relative to the press-web

direction.

When assigning the placement for the sym-

bol, a designer should consult the appropri-

ate application standards governing its use.

Among the typical concerns are repeatable

placement guidelines for specific packaging

types (for human-factor considerations),

adequate space for quiet zones, specific gov-

ernment labeling requirements, and the

physical layout of the package itself. A pack-

aging engineer should be consulted to make

sure the symbol will not be obscured or

damaged during production, (e.g., over a

carton edge, beneath a carton fold, beneath

a package flap, or covered by another pack-

aging layer).

Once the proper placement is determined,

the printing company should be consulted

Table 12

Recommended GCMI colors for natural kraft

substrate.

CODE COLOR CODE COLOR

3213 Aqua 3086 Blue

90 Black 52 Brown**

30 Blue 523 Brown

31 Blue 20 Green

32 Blue 21 Green

33 Blue 22 Green**

38 Blue 24 Green

39 Blue 25 Green

300 Blue 29 Green

387 Blue 2008 Green

394 Blue 2014 Green**

* Now GPI (Glass Packaging Institute)

** Least desirable of the recommended colors

FBA EDITION VIII GCMI* COLORS

From Fibre Box Association (FBA) Guideline for Direct Contact Printing of Bar

Code Symbols on Corrugated. Reprinted here with permission from the FBA.

before assigning the symbol rotation. When

using flexographic printing, the bars should

run parallel to the press web direction,

whenever possible. This is shown as a pick-

et-fence orientation (Figure

). If the bars

are required to run perpendicular to the

press direction (ladder orientation), distor-

tion of the symbol to account for the plate-

roll circumference should be avoided. This

lack of distortion will alter the overall width

of the symbol, but will provide dimensional

integrity by avoiding rounding errors. The

bar code design software may account for

the “distortion” input variable in the design

stage, (refer to UCC Guidelines for

Providers of EAN/UPC Symbol Design

Software, Section 1.8.4). If it does, the pro-

cedures given by the software provider

should be followed. If the software does not

account for distortion when the symbol is

created and distortion is unavoidable, out-

putting the film at higher resolutions (e.g.,

4000 dpi) is advised to avoid reintroducing

rounding errors.

To specify the proper placement and orien-

tation of the bar code on the design, an FPO

(For Position Only) symbol should be used

(Figure

). This symbol should be clearly

labeled “FPO” so that it is understood to indi-

cate size, color, orientation and placement

only, and that it may not be encoded properly

or produced at the specified resolution.

FILM MASTERS

Many flexographic printers require precise

bar code film artwork, called a film master, to

manufacture printing plates for bar codes

(Figure

). Essentially a film master is an

extremely accurate photo-representation of a

bar code, in either positive or negative film.

The super-accuracy of film masters cannot be

duplicated by the typical photo processes

available to most printers, so a reliable film

master producer must be used. This is per-

haps the most essential step a printer can

take. Film master tolerances are strictly con-

trolled and, in the case of most UCC/EAN

symbols, are often less than ± 0.0002" (0.0051

mm) for bar and space widths. Tolerances for

these symbols are set by the UCC in the U.P.C.

BAR CODES 67

Whenever possible,

flexographers should

opt for the picket-fence

placement, which

means the bars are

running

parallel to the web

direction.

An FPO label denotes

that the bar code

shown is only intended

to indicate orientation,

size, color, etc.; it is not

to be printed.

Picket Fence

Ladder

68 FLEXOGRAPHY: PRINCIPLES & PRACTICES

Film Master Verification Manual (for U.P.C.

symbols) and the ANSI/UCC6 – Application

Standard for Shipping Container Codes (for

ITF symbols and UCC/EAN-128 symbols used

as shipping container codes).

Certain parameters are vital in the projec-

tion and use of Film Masters. Designers and

printers should note that the following items

should appear on the Film Master:

• magnification factor;

• selected bar-width reduction;

• product identification, including com-

pany name, in English language;

• an optional test square (outside the

symbol area) for emulsion studies (this

should be incorporated in the film, not

affixed on a separate label);

• printing process for which the film mas-

ter is intended (i.e., flexo);

• identification of Film Master supplier;

and

• date of film master manufacture.

DIGITAL BAR CODE CAUTIONS

Today it is becoming more common for

bar code designers to design and store their

bar codes in a digitized format. Many good

bar code design software packages exist for

this purpose. However, there is an important

word of caution. If the digital bar code is

used in replacement of a film master, great

care must be taken to insure that all final

specifications will be met in the printing

process. This includes sufficient room for

the established quiet zones around the sym-

bol, an accurate bar-width reduction (BWR),

a correctly calculated check digit, the prop-

er magnification within symbol tolerance,

and the corrected imaging resolution.

Specifying the addressable imaging resolu-

tion for bar code symbol output is critical to

providing proper dimensions for the bars

and spaces. This is because a bar code,

unlike typical graphic images, is machine-

readable based on predictable decoding for-

mulas. If it is not designed (encoded) with

corrections to the target size based on the

addressable imaging resolution, rounding

errors will occur in most cases.

When the print buyer provides a target size

(magnification or X-dimension) for the sym-

bol to the design or printer, a new size should

be provided by the bar code design software

to “correct symbol dimensions” for the

imagesetter resolution specified. This

process is called “corrected magnification” or

“corrected size” when applied to the original

bar and space widths and “corrected BWR”

when applied to the amount of target BWR.

For example, if an EAN/UPC bar code

with a target X-dimension of 0.0130" mea-

sures 16.5 dots wide based on a 1270 dpi

imagesetter resolution, the symbol size is

1( A bar code film

master is a precise

photo-representation

of a bar code in film.

Its use ensures accurate

reproduction of the bar

code.

SAMPLE FILM MASTER

(WITH EXAMPLE OF SUGGESTED COPY)

Test

Square

(Optional)

1) Magnification Factor 1.20

2) Selected Bar Width Reduction 0.003"

3) 16-oz. Green Beans

Valley Bean Company

4) Test Square

(optional, used for emulsion studies)

5) Printing Process - Litho

6) ABC Film Master Company

7) Date 6/85

corrected by truncating the 16.5 dot symbol

module to 16 dots wide (an integer number)

consistently across all symbol modules. The

width of the dot (0.000787") multiplied by 16,

gives the “corrected” symbol module width

of 0.0126" (96.9% of 0.0130"), instead of the

target width of 0.0130" (Figure

Correcting symbol dimensions slightly to

accommodate the addressable output reso-

lution of the imagesetter is far more impor-

tant to bar code scanning performance than

creating a symbol with any specific size.

Because of this, production-ready symbols

should be designed only when output resolu-

tion is known, and digital bar code files

should only be resized using the bar code

design software package that originated

them. Another designer should not alter these

specifications at any later stage within anoth-

er illustration or page-layout software pro-

gram. The digital bar code file should also be

linked to the output resolution attribute in

some way to assure the symbol is output at

the resolution specified when it was created.

And finally, using the resizing tool on bar

codes within an illustration or page layout

software package is strongly discouraged, as

the resulting symbol may not scan.

BAR CODES 69

Correcting bar code

dimensions for output

resolution through a bar

code design software

program.

Symbol Magnification

Enter Target Magnification:

Enter Imaging Resolution:

“Corrected” Magnification:

100%

1270 dpi

96.9%

70 FLEXOGRAPHY: PRINCIPLES & PRACTICES

for Direct Contact Printing Bar Code Symbols

on Corrugated, available from the Fibre Box

Association.

In general, the guideline pro-

vides recommendation for the purchase of bar

code printing plates, a brief discussion and

recommendation of inks in GCMI colors, and

a section on production practices.

VERIFICATION AND MAKING

THE GRADE

It can’t be stated any clearer: bar codes

either scan within tolerance or they don’t.

That means it is worth the investment in time

and resources to insure that the quality goes in

before the bar code goes on. And that, in turn,

means that every flexographic printer printing

bar codes should consider migrating to a

properly calibrated ANSI/UCC5-based verifier

Bar Codes

in the Pressroom

Scan Reflectance Profile

(SRP) is generated by a

single scan by a verifier.

he production process begins

with the receipt of a work order

that includes a bar code. The

first thing that must be done is

to compare the bar code num-

bers on the work order against

the numbers beneath every symbol on the

plate. It should never be assumed that every

number on the plate will be the same. Also,

the plate should be checked for defects such

as nicks, plugs, buckles or tears. If an error

or defect is discovered in the plate, it should

be quarantined or destroyed according to

company procedures. The numbers beneath

a bar code symbol should never be revised

by cutting or otherwise altering the plate.

A CORRUGATED TIP

When printing directly on a corrugated sub-

strate, an excellent resource is the Guideline

Quiet

Zone

Quiet

Zone

Spaces

Bars

Reflectance

100%

See Resources at the end of this chapter for contact information.

to bring their quality assurance program into

alignment with the direction of the future.

Following the direct visual inspection of

the plate, it is recommended that the printer

test for an acceptable ANSI symbol grade in

the first piece approval process. There are

two types of ANSI grades. A scan profile

grade results from analyzing an SRP (scan

reflectance profile) obtained from a single

scan of a bar code by a verifier (Figure

In Figure

, each scan profile grade is

established by taking the lowest of eight

parameter scores (or nine if a quiet zone

measurement is included as for the UCC/

EAN). Table 13 lists the details of these para-

meters.

An ANSI symbol grade (Figure

) is

determined by analyzing the results of 10

scan profile grades taken at equally spaced

intervals down the symbol and averaging

them together for one grade.

For further details on this ANSI-based ver-

ification, refer to

AIM USA: A Laymen’s Guide to ANSI Print

Quality.

ANSI: ANSI X3.182 Bar Code Print Quality

Guideline.

UCC: Technical Bulletin #1 – Understanding

UCC Specified Methods for Assessing

EAN/UPC Quality, ANSI/UCC5 – Quality

Specification for the U.P.C. Printed Symbol,

or Guidelines for Producing Quality Symbols.

ANSI grades should always be specified by

the print buyer with three key pieces of

information – the minimum ANSI grade

BAR CODES 71

The scan profile grade

is determined by

selecting the lowest of

the parameter scores

generated in the SRP. In

this case, the scan

profile grade is a C.

By averaging 10 scan

profile grades, an ANSI

symbol grade can be

calculated.

Edge Determination Pass = A

Minimum Reflectance 3% = A

Symbol Contrast 70% = A

Edge Contrast 47% = A

Modulation 55% = C

Defects 17% = B

Decode Pass = A

Decodability 60% = B

Quiet Zones Pass = A

See Resources at the end of this chapter for contact information.

Scan Grade 1 B = 3.0

Scan Grade 2 C = 2.0

Scan Grade 3 C = 2.0

Scan Grade 4 B = 3.0

Scan Grade 5 B = 3.0

Scan Grade 6 B = 3.0

Scan Grade 7 C = 2.0

Scan Grade 8 B = 3.0

Scan Grade 9 A = 4.0

Scan Grade 10 B = 3.0

Average Grade 2.8 or B

72 FLEXOGRAPHY: PRINCIPLES & PRACTICES

(specified as a grade point average), the ver-

ifier aperture to be used, and the verifier

wavelength to be used. For example, all

EAN/UPC symbols should receive a passing

ANSI symbol grade of “1.5” (C grade) or bet-

ter when using a verifier with the 0.006"

aperture and a wavelength of 670 nanome-

ters ±10. This would be specified as

1.5/06/670 on a purchase order.

It should be noted that the UCC makes one

exception for its symbols in regard to the min-

imum “C” grade. This exception is for ITF

symbols directly printed on corrugated. For

the ITF symbol (which is never expected to be

scanned in a retail checkout lane), a minimum

grade of “D” is permitted due to the capabili-

ties of industrial scanners which are used in a

distribution or logistics scanning environment

and ITF’s simple encodation characteristics.

Flexo printers will find an excellent document

on quality control for printing ITF symbols on

corrugated in the previously mentioned

Guideline for Direct Contact Printing of Bar

Code Symbols on Corrugated.

Although it may not be possible for all

packaging materials or printing processes,

the ANSI grade minimum specified by the

application standard should be exceeded by

one letter grade at the end of the printing

process wherever possible. Bettering the

grade at the time of printing can be helpful

in overcoming any symbol quality lost due

to the packaging, labeling or distribution

process of the final, filled product.

When analyzing symbol quality on trans-

parent or translucent substrates, the final

product should be simulated as clearly as

possible. For example, when printing a

Table 13

1. EDGE DETERMINATION

Counts the number of crossings over the

global threshold of the scan-reflective profile

to verify whether the number obtained con-

forms to a legitimate bar code symbology.

2.MINIMUM REFLECTANCE

Measures whether the reflectance value of at

least one bar is, at most, equal to or less then

half of the highest reflectance value for a

space.

3.SYMBOL CONTRAST

Measures the difference between the largest

and smallest reflectance values in a scan.

4.MINIMUM EDGE CONTRAST

Measures the smallest value for edge contrast

in a scan reflectance profile between a bar and

adjoining space.

5.MODULATION

Measures the way a scanner sees narrow

spaces or bars in relation to wider spaces or

bars.

6.DEFECTS

Measures the voids present within the bars

and the spots present within the spaces or

bars.

7.DECODE

Applies specific rules to the bars and spaces

of EAN/UPC symbols to decode them into a

series of digits and guard bars. The

ANSI/UCC5 based verifier passes the symbol

for decode when it is able to decode the

EAN/UPC symbol including its guard patterns,

and the check digit is consistent with the other

digits.

8.DECODABILITY

Measures how close the scan reflectance pro-

file of the printed symbol is to approaching

decode failure.

9.QUIET ZONES

An area of free printing which precedes the

leftmost bar and follows the rightmost bar in a

UCC/EAN symbol.

ANSI SCAN-REFLECTIVE PROFILE PARAMETERS

white EAN/UPC symbol background on a

clear plastic bag, try to find out what the bag

will be filled with in the packaging process.

If it is white notebook paper this could actu-

ally boost the white background, but if it is

black jellybeans the white may appear gray

to a scanner. If simulating the package is

impractical, the printed symbol should be

verified twice, once by laying the symbol

over a black background and next over a

white background. The worst of the two

ANSI symbol grades should simulate the

worst case scenario.

VERIFYING THE VERIFIER

It is important to emphasize the importance

of working with a properly calibrated verifier.

ANSI-based verification instruments are an

important tool in the assessment of quality

symbols, but their performance is only bene-

ficial when they are calibrated and used

according to manufacturer’s recommenda-

tions. Before the UCC released the new spec-

ification for assessing printed UPC bar code

quality (ANSI/UCC5 – Quality Specification

for the UPC Printed Symbol), they developed

a mechanism for everyone in the supply chain

to use to “verify their verifier.” The Calibrated

Conformance Standard Test Card for EAN/

UPC Symbol Verifiers is a physical set of

EAN/UPC symbols designed to test particular

characteristics of ANSI/ UCC5 based verifica-

tion equipment (Figure

The standards are manufactured on spe-

cial materials and are made traceable to

NIST (National Institute of Standards and

Technology). This traceability is facilitated

through a custom-designed piece of hard-

ware (nicknamed “the Judge”) and has been

engineered to measure the various attributes

outlined in ANSI X3.182, published in 1990,

and ANSI/UCC5, published in 1994. The

Judge has also been made traceable to NIST.

The idea behind the standard is to test, on

a regular basis, if the verification equipment

is operating within the range of tolerance for

ANSI measurements as published by the ver-

ifier manufacturer. The test cards are espe-

cially important in heavy use applications,

where various operators may be involved, or

where a new user is learning to use the veri-

fier properly and needs a control target.

Verifier operators, on a routine basis set by

company procedures, should scan each of

the symbols on the standard to determine if

the verifier device is providing the values

listed on the test card. If it is not, they should

work with the verifier manufacturer to

determine if they are using the equipment

properly or if the unit is not calibrated.

ROLL WITH THE FLOW

During the production run, maintaining a

clean transfer of ink, proper bar widths and

consistent symbol colors are critical to

BAR CODES 73

The Calibrated

Conformance Standard

for EAN/UPC symbol

verifiers is designed to

test particular character-

istics of ANSI/UCC5-

based verification

equipment.

74 FLEXOGRAPHY: PRINCIPLES & PRACTICES

repeatable symbol quality. Flexographic

printers should consider these factors when

making press adjustments and follow com-

pany procedures on production sampling.

Even if the plate passes inspection, produc-

tion defects are common during the press

run. These would be categorized as voids in

bars, spots in the bar code spaces or quiet

zones. Defects can be caused by factors such

as cleaning the plate during the run, debris

being caught in an ink cell or under a doctor

blade, or the plate being damaged. If the

defect is temporary and correctable it may be

decided to flag the affected portion and con-

tinue production. If the defect cannot be cor-

rected, the company’s procedures to make a

go or no-go decision should be used.

If prepress has made the proper BWR based

on a contemporary press characterization, the

symbol bars should remain within the speci-

fied width throughout the run. This relation-

ship between the BWR in prepress is critical

to quality symbol production. If the press

characterization analysis is correct, a symbol

of adequate size and bar width reduction is

made ready for the range of print gain experi-

enced on the press. If the BWR and minimum

size are correct based on prior experience and

there is still poor symbol quality, there may be

a problem with press factors such as press set-

tings, ink metering, mounting material thick-

ness for the plate, cylinder tolerance or press

maintenance. The substrate may also be eval-

uated if it differs fundamentally from the one

used in the characterization process. When-

ever a significant variable from the original

characterization is introduced, a new charac-

terization may be warranted.

When it comes to symbol color, it is under-

stood that colors will vary somewhat

throughout the run. This is due to changes in

ink viscosity, press speed, drying tempera-

ture, ink chemistry and other factors.

However, significant color changes should

be controlled and avoided throughout the

run. It is wise to develop an acceptable range

for the bar color and space (background)

colors for major substrates. This will avoid

beginning the production process with a

symbol of marginal contrast (which will pro-

duce material outside of specification with

any process variation).

Finally, bar code symbols with different

numbers should not be mixed on a roll or in

a box unless specified by the customer or

company procedures. When bar code sym-

bols are produced via a flexographic plate,

they will almost never be printed sequential-

ly. If batches of symbols become mixed on a

printed roll they might be used on the wrong

product, package or coupon when automati-

cally packaged or applied downstream.

Unless otherwise specified, it is wise to sep-

arate symbols with different numbers into

batches as they are produced and later when

they are packaged and shipped. If the batch-

es are of a size that prohibits separating

them, company procedures should be fol-

lowed to carefully identify each batch.

RAISING THE BAR

Flexographic printers have consistently

“raised the bar” in the production of quality

bar codes. From the very beginnings over 25

years ago, bar code users have looked to

flexography for solutions that provide the

essential identification and tracking aspects

of bar code symbols on large volumes of

products, packages and containers. Today,

backed by an arsenal of new tools and tech-

nologies, flexographic printers are produc-

ing the highest quality bar codes in their his-

tory. Organizations such as the Uniform

Code Council, the Fibre Box Association,

AIM USA and the FTA are dedicated to rais-

ing these quality achievements to an even

higher level. With a sense of partnership and

a fundamental understanding of the underly-

ing technology, flexography and bar codes

will continue to improve their symbiotic

relationship for decades to come.

BAR CODES 75

Resources

ADDRESSES OF ORGANIZATIONS MENTIONED IN THIS CHAPTER

(Valid as of PublicationDate)

ORGANIZATION TELEPHONE FAX WEBSITE

AIM-USA (Automatic Identification Manufacturers)

634 Alpha Drive

Pittsburgh, PA 15238 (412) 963-8588 (412) 963-8753 www.aimusa.org

ANSI (American National Standards Institute)

11 West 42nd Street

New York, NY 10036 (212) 642-4900 (212) 302-1286 www.ansi.org

EAN International

Rue Royal, 145, B-1000

Brussels, Belgium 32-2-227-1020 32-2-227-1021 www.ean.be

ECCC (Electronic Commerce Council of Canada)

885 Don Mills Road, Suite 301,

Don Mills, Ontario

Canada M3C 1V9 (416) 510-8039 (416) 510-8043 www.eeec.org

FBA (Fibre Box Association)

2850 Golf Road, Suite 412,

Rolling Meadows, IL 60008 (847) 364-9600 (847) 364-9639

UCC (Uniform Code Council)

7887 Washington Village Drive, Suite 300

Dayton, OH 45459 (937) 435-3870 (937) 435-7317 www.uc-council.org