Paper 101

Paper Properties and Their Impacton the Printing Process

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Why is Knowing Paper Important to you?Why is Knowing Paper Important to you?

1) Paper and other substrates on which an image is printed can represent 25-55% of the final cost of a printed job

2) Having a working knowledge assures that the paper selected is the most appropriate and cost effective for the application

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Basics of Paper ManufacturingBasics of Paper Manufacturing

1. Forests

2. Logging – debarking

3. Pulp refining

4. Forming Section (wet end), Press Section (water removed), Drying Section (sets moisture levels)

5. Calendaring (final stages for smoothness, etc)

6. Cutting down the 40,000 lb plus rolls ready for finishing (rolls or sheets)

6.

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Paper Making Kit

Plus, a Question

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Paper Machines are the length of football fields!!!Paper Machines are the length of football fields!!!

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Key Properties of PaperKey Properties of Paper

Fibers

Basis Weight

Caliper (Thickness)

Grain Direction

Formation

Surface Sizing

Opacity

Brightness

Whiteness

Absorption

Smoothness

Paper Strength

Stretch

Moisture

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Wood Fibers Used in Paper ManufacturingWood Fibers Used in Paper Manufacturing

The fibers used in paper manufacturing play a key part in what happens to it later

•Hard woods

•Southern climates

•Shorter fibers

•Weaker, yet smoother

•Coniferous trees

•Northern climates

•Longer Fibers

•Stronger, yet rough

•Eucalyptus trees

•Southern hemisphere

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Fibers Used in Paper ManufacturingFibers Used in Paper Manufacturing

Paper can be made from MANY sources, but wood fibers are used more often

Other paper fibers sources can include:

• Cotton and other plants (i.e. hemp)

• Recycled fibers

• Hemp

• Rice

• Even old jeans!

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Basis Weight of Paper ---- Huh?Basis Weight of Paper ---- Huh?

Basis Weight is paper weight in pounds of a ream (500 sheets) in it’s basic size

Web Printers purchase paper by weight (pounds) in rolls. Sheet fed printers typically order by number of sheets needed for the job.

Example:

The basic size for Book papers is 25” x 38”. The measurement of basis weight for book paper would be calculated by taking 500 sheets each measuring 25” x 38” and placing it on a scale. If the weight of the 500 sheets was 50lb., we would call that paper 50 lb. Book. If the weight was 60 lb. it would be 60 lb. book.

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Basis Weight Types – Basic SizesBasis Weight Types – Basic Sizes

1) Cover (20” x 26”)

a. Heavy weight papers used for book covers, advertising, direct mail, etc.

2) Index (22 ½” x 28 ½” and 25 ½“ x 30 ½ “)

a. Usually available in smooth and vellum finishes. Used in file folders, index cards, etc.

3) Tag (24” x 36”)

a. Smoother surface than index, making it ideal for high-speed folding, embossing, etc.

4) Bond (17” x 22”)

a. Commonly used for letters and business forms. Example: paper in your books is 20# Bond

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Basis Weight Types – Basic SizesBasis Weight Types – Basic Sizes

5) Board (22 ½” x 28 ½”)

a. One of the board grades, with a softer surface than index or tag. Used for POP, signage, book covers (soft), advertising etc.

6) (25” x 38”)

a. Coated Book

b. Uncoated Book

c. Text

d. Offset

Much easier outside the U.S.…

They use only one Basis Weight.

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Let’s look at some

Swatch Books

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Basis Weight as compared to CaliperBasis Weight as compared to Caliper

Basis weight is the weight in lbs of a ream of paper in its’ basic size

Caliper is the thickness of the paper

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FormationFormation

Formation is the physical distribution and orientation of fibers and other solid constituents in the structure of a sheet of paper which affects the appearance and other physical properties.

Formation is also referred to as “look through” because the formation can sometimes be observed by looking through the sheet.

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FormationFormation

Formation can have a big impact on print quality for:

a. Ink Mottle - A “wild” formed sheet will result in the ink absorbing into the structure unevenly which then causes the ink to day with a mottled appearance.

b. Ink Show-Through (Printed Opacity) - If a sheet is “wild” with areas of fiber surrounded by areas of no or little fiber, ink will bleed at differing rates resulting in a strong “blotchy” ink show-through.

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Surface SizingSurface Sizing

Surface is a key to good press runnability!

a. Uncoated papers need to “seal” the sheet to reduce press contamination (fiber, debris, etc.).

b. Sizing used for uncoated paper consists of a starch applied to the paper during the paper making process.

c. Various types of starches are used: Corn Potato Ethylated Cationic Starch Oxidized Etc.

Good surface sizing is critical to achieve good press performance!

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Surface SizingSurface Sizing

Starch is applied by a simple “coating device” located between the two drying sections of the paper machine. There are several types used by paper makers to applied starch. A typical size press would look like this:

Paper

Size Press Rolls

Starch Solution

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Optical PropertiesOptical Properties

1) There are five main optical properties that influence the visual perspective of a printed sheet:

a. Opacity

b. Brightness

c. Whiteness

d. Color

e. Gloss

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OpacityOpacity

Opacity relates to the show-through of the printed image from the opposite side of the sheet, or the sheet under it.

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BrightnessBrightness

Brightness affects the contrast, brilliance, snap or sparkle of the printed sheet. It is the percent of reflectance at a standard single wavelength.

a. Don’t confuse “whiteness” with “brightness”.

b. Whiteness is the amount of Red, Blue and Green reflectance and that will be discussed shortly

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73-78.973-78.9

79-82.979-82.9

83-84.983-84.9

85-87.985-87.9

88+88+

AF&PA Brightness ComparisonAF&PA Brightness Comparison

81.9 and below81.9 and below

82-86.982-86.9

87-90.987-90.9

91 +91 +NO.1NO.1

NO.2NO.2

NO.3NO.3

NO.4NO.4

GE BRIGHTNESS GE BRIGHTNESS METERMETER

PremiumPremium

Old New

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WhitenessWhiteness

1) Whiteness is the ratio of Red, Green and Blue reflectance.

a. An attribute of a diffusing surface which denotes its similarity in color to preferred or standard white.

A psychological attribute of a color stimulus. A “white” color stimulus is perceived as void or any hue or grayness.

b. White can be in many different hues.

Known as “cold” if on the blue side.

Known as “warm” if on the red side.

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GlossGloss

1) Gloss is the relative amount of incident light reflected from a surface.

a. Paper Gloss - Degree to which a paper surface appears “shiny”.

b. Printed Gloss - Degree to which a printed ink appears “shiny”.

2) Paper Gloss is attained by the paper maker through calendering and pigments.

a. The higher the calendaring, the higher the gloss.

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CalenderingCalendering

Paper

Calendar Rolls

Pressure and heat combine to make the sheet shinier and glossier. However, the more you calendar, the thinner the sheet becomes.

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Coated Paper Finish ExamplesCoated Paper Finish Examples

Finish Calendering Paper Gloss Surface Suggested

Matte None Not apparent Rough/toothy, non-glare

Texture, Text

Dull Minimal Very Low Smooth, non-glare

Illustrations, Black & White

Satin/Velvet Light Low - Moderate

Smooth and soft to the touch

Text, texture, fabrics

Silk Light Moderate Smooth and silky to the touch

Fine art, skin tones, detail, readability

Gloss High High Smooth, shiny, slick

Hard, shiny surfaces, no scuff

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Gloss Finished SurfaceGloss Finished Surface

Calendared using smooth and polished steel rolls

Smoothest surface

Highest printed ink gloss

Highest plain paper gloss of coated finishes -- reflective

Highest ink hold-out, lowest dot gain

Best for showing fine detail

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Matte Finished SurfaceMatte Finished Surface

Non-glare surface

Textured, Roughest

Minimally calendered

a. Lowest paper gloss

b. Lowest printed ink gloss

c. Greatest amount of contrast

between paper and ink

Replicates look and feel of uncoated

End Uses: Text, charts, anywhere to minimize eyestrain, writeable

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Silk / Dull Finished SurfaceSilk / Dull Finished Surface

Non-glare surface

Micro-embossed surface,

pattern from imparted by calendar rollers

Excellent ink holdout for sharp halftone reproduction

Softer images

Richer halftones and solids than mattes

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Velvet Finished SurfaceVelvet Finished Surface

Coating formula and on line calendaring technique produce a smooth, low gloss paper

Looks like a dull -- prints like a gloss

Higher paper gloss than a dull

Similar coat weight to gloss

Smoother, harder surface than a dull

More uniform printing surface than a matte

Distinctive, silky feel

A.K.A. Satin, Suede

Global Coated Papers: Worlds of DifferenceGlobal Coated Papers: Worlds of Difference

North American AsianEuropean

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Uncoated versus Coated PapersUncoated versus Coated Papers

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Uncoated SurfaceUncoated Surface

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Un-Coated Print DotUn-Coated Print Dot Coated Print DotCoated Print Dot

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SmoothnessSmoothness

Measures texture and topography

Necessary for continuous, non-mottled ink film

Higher ink gloss

More pure ink color/broader tonal range

More accurate reproduction

Greater detail for critical colorProductsCorporate Identity

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StrengthStrength

1) Strength of paper is more dependent on the nature of its fiber than its thickness.

a. High bursting strength is achieved by closely intermingling long pulp fibers during the forming of the sheet on the paper machine.

b. Fibers are long and tear in the cross machine direction is always higher than tear in the machine direction.

This is because the greatest number of fibers lie across the path of the cross machine.

c. Tear strength is important when producing a sheet with perforations. The “perf” should not fall apart of be difficult to separate.

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StretchStretch

Stretch is the amount of distortion paper undergoes under tensile strain. Stretch is generally much greater in the cross direction than in the machine direction.

a. Excessive stretch with web or sheetfed papers will result in poor registration or fanning problems.

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MoistureMoisture

The Moisture content is the percent of moisture found in the finished paper.

a. Can range from a low of 4.0% to a high of 7.0%.

b. Heat-set web paper with low moisture (< 5.0%) will dry out in the heatset oven causing cracking at the fold.

1 ton of paper at 5% moisture level will contain 100 lbs. of water!

Remember earlier when we talked about the paper machine? Paper is 95 to 98% water as it enters the paper machine! Moisture in paper plays a

part from the beginning all the way through the printing process.

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MoistureMoisture

Paper likes to come to equilibrium with its environment.

a. Paper brought into a humid pressroom absorbs moisture at the edges while the rest of the pile or roll (towards the center) will remain unchanged.

b. As this process occurs, the edges containing more moisture will increase in size resulting in wavy edges.

c. Paper brought into a dry pressroom will give up moisture, at the edges first, shrinking the paper resulting in tight edges.

This will result in wrinkles, fanning and bad registration.

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Specialty Grades of PaperSpecialty Grades of Paper

Fancy finishes

Synthetic Papers

Magnetic Papers

Pressure Sensitive (i.e. “sticky back”)

Carbonless

Etc

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Educational ResourcesEducational Resources

1) Spicers Papera. Environmental calculator

b. other tools

2) International Paper Pocket Pala. www.ippocketpal.com

3) The “Coated U” from Appleton

4) Sappi Standards

5) Paper mill swatch books

6) Many more!

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OFFICESCorporate Office 800-774-2377 or 562-698-1199Los Angeles 800-774-2377 or 562-698-1199Las Vegas 702-736-4441Phoenix 800-352-5749San Francisco 866-774-2377Denver 303-373-9655Portland 800-452-8401 or 503-405-0100Seattle 253-518-0015 or 800-231-5136Honolulu 808-832-0001Minneapolis 877-634-0024Kansas City 888-333-0055St. Louis 314-801-6100Salt Lake City 801-364-0113 or 866-403-6609