Screen Screen PrintingPrinting

History - beginningsHistory - beginnings

• Screen-printing first Screen-printing first appeared in a appeared in a recognizable form in recognizable form in China during the Song China during the Song Dynasty (960–1279 CE). Dynasty (960–1279 CE). Japan and other Asian Japan and other Asian countries adopted this countries adopted this method of printing and method of printing and advanced the craft using advanced the craft using it in conjunction with block it in conjunction with block printing and paints.printing and paints.

History – western introductionHistory – western introduction

• Screen-printing was introduced to Western Screen-printing was introduced to Western Europe from Asia sometime in the late Europe from Asia sometime in the late 1700s, but did not gain large acceptance 1700s, but did not gain large acceptance or use in Europe until silk mesh was more or use in Europe until silk mesh was more available for trade from the east and a available for trade from the east and a profitable outlet for the medium profitable outlet for the medium discovered.discovered.

History – popularity increasesHistory – popularity increases• Screen-printing was first patented in Screen-printing was first patented in

England by Samuel Simon in 1907. It was England by Samuel Simon in 1907. It was originally used as a popular method to originally used as a popular method to print expensive wall paper, printed on print expensive wall paper, printed on linen, silk, and other fine fabrics. Western linen, silk, and other fine fabrics. Western screen printers developed business screen printers developed business policies intended to keep secret their policies intended to keep secret their workshops' knowledge and techniques.workshops' knowledge and techniques.

• Originally a profitable industrial technology, Originally a profitable industrial technology, screen printing was eventually adopted by artists screen printing was eventually adopted by artists as an expressive and conveniently repeatable as an expressive and conveniently repeatable medium for duplication well before the 1900s. It medium for duplication well before the 1900s. It is currently popular both in fine arts and in is currently popular both in fine arts and in commercial printing, where it is commonly used commercial printing, where it is commonly used to print images on T-shirts, hats, CDs, DVDs, to print images on T-shirts, hats, CDs, DVDs, ceramics, glass, polyethylene, polypropylene, ceramics, glass, polyethylene, polypropylene, paper, metals, and wood. paper, metals, and wood.

The process of forcing ink The process of forcing ink through a porous fabric through a porous fabric and the open areas of a and the open areas of a stencil to produce an stencil to produce an image.image.

Screen Printing ProcessScreen Printing Process

1960’s to present1960’s to present

• Credit is generally given Credit is generally given to the artist Andy to the artist Andy Warhol for popularizing Warhol for popularizing screen printing screen printing identified as serigraphy, identified as serigraphy, in the United States. in the United States. Warhol is particularly Warhol is particularly identified with his 1962 identified with his 1962 depiction of actress depiction of actress Marilyn Monroe screen Marilyn Monroe screen printed in garish colors.printed in garish colors.

Two terms commonly used: Two terms commonly used: Serigraphy (in the field of Serigraphy (in the field of fine arts) and Screen fine arts) and Screen Printing used in the graphic Printing used in the graphic communications industry.communications industry.

Applications for Screen Applications for Screen Printing:Printing:• PostersPosters• Plastic bottlesPlastic bottles• Drinking glassesDrinking glasses• Soda bottlesSoda bottles• Mirrors, metal surfacesMirrors, metal surfaces• WoodWood• TextilesTextiles• Printed circuit boardsPrinted circuit boards• Product displaysProduct displays• Vinyl bindersVinyl binders

Advantages of Screen PrintingAdvantages of Screen Printing

• Images can be printed on a wide variety of Images can be printed on a wide variety of substrates.substrates.

• The production process is relatively easy.The production process is relatively easy.• Capital expenditures are low compared to other Capital expenditures are low compared to other

printing processes.printing processes.• Images can be printed with glitter, flock, and Images can be printed with glitter, flock, and

other decorative finishes.other decorative finishes.• The ink film is very resilient due to the extreme The ink film is very resilient due to the extreme

thickness of the ink deposit.thickness of the ink deposit.

Disadvantages of Screen Disadvantages of Screen PrintingPrinting

• The process is usually limited to flat, relatively The process is usually limited to flat, relatively thin substrates, such as paper, metal, or thin substrates, such as paper, metal, or plastic.plastic.

• Rate of production is slow.Rate of production is slow.• Ink mileage is poor.Ink mileage is poor.• Excessive drying times may be necessary.Excessive drying times may be necessary.• Details and fine line images may be difficult to Details and fine line images may be difficult to

print.print.

Basic tools & Equipment for Screen Basic tools & Equipment for Screen Printing:Printing:

• FrameFrame

• SqueegeeSqueegee

• Vacuum Printing FrameVacuum Printing Frame

• Printing TablePrinting Table

• Screw DriverScrew Driver

• DividerDivider

• HammerHammer

• Sharp KnifeSharp Knife

FramesFrames Materials◦ Wood– less expensive, warps or rots faster◦ Aluminum– more expensive, durable

Sizes◦ Labeled according to I.D. (inside dimension)

Recommended sizes for printing: at least 6 inches beyond. Image size at top and bottom: at least 6 inches on each side.

Types◦ Wooden with groove: made for attaching fabric with a rope.◦ Wooden or aluminum without a groove: fabric attached with glue.◦ Retensionable aluminum: screen can be tightened repeatedly.

FabricsFabrics• Two main functions

• Provide support for stencil.• Control ink flow.

• Mesh count: how many opening per inch.• Fine mesh=100 count (ct) up to 500 ct. mesh

• More detail and uses less ink; feels softer to touch.• Less likely to smear on non-absorbent substrates.

• Coarse mesh=40 to 100 ct. mesh• Heavy ink deposit (good for light inks on dark shirts.• Better opacity

FabricsFabrics cont…cont…

Two general typesMultifilament: tiny strands twisted togetherIncludes: polyester and silkGood for film stencils (like amber film)—sticks to it better

Monofilament: (mono= one) single strand of threadGood for liquid emulsionIncludes polyester; stainless steelGood for fine detail; easier to clean than multifilament

FabricsFabrics cont…cont…Colored Fabrics: used to reduce unwanted glare during

exposure, called “halation’s.” Halation’s cause distortion around edge of images.

Chemicals Used In Screen Printing

Autosol.Photocure Texture.Sp-1300.Benzene.Carbon tetra chlorideDetergent powderGlue(swan Aica)Cold and clean water

Light Sensitive Film For Screen Printing

Direct filmIndirect film (Pre-sensitized gelatin film & Pre-sensitized synthetic polymer coated film. Known as five star film) Indirect film used for indirect stencil making.

StencilsStencils (Two Types) (Two Types) Non-photographic: hand cut (i.e. amber film, or paper) Photographic: (light sensitive) photo emulsion (liquid)◦ Exposure process: Some type of light is used to harden emulsion.

Why does the image spray out?- The particles in the emulsion that the positive was not covering, was hardened by the UV light.

◦ Overexposure: results in image NOT spraying out completely.

◦ Underexposure: results in scuming (an almost invisible film forms on stencil from the still soft emulsion running across screen as it dries)

Stencil Making

There are two way of stencil making.Direct process.Indirect Process

Stencil Making of Direct Process

In a darkened room or in a room with a yellow safe light, pour the emulsion into a scoop coater

Coat the screen, applying 2 thin coats of emulsion on each side of the screen.

If your scoop coater is smaller than the width of your screen, coat as shown in this slide.

Once you have one coat on this side, turn the screen upside down to apply the second coat. Then apply two thin coats onto the back side of the screen, again flipping the screen upside down in between coats.

Wipe off any excess emulsion that gathers around the edges.

Store the coated screens in a dark room or light-tight box until they are dry. Screens should dry with the flat side down (the side you used the squeegee on should be facing up). They need to dry perfectly flat. If the screen is tilted even the slightest bit, then the emulsion might dry unevenly and run off the screen.

If you are coating more than one screen, stack them using small blocks in between each one.

Once the screens are dry they may be put in black plastic garbage bags until you are ready to expose them

Expose the silkscreen with the students’ Film Positives. There are different types of exposing units. This one is a light table with clear glass and florescent light bulbs.

This process involves direct contact exposure. There must be no space between the Film Positive and the screen. Build a flat that is larger than your image, but small enough to fit inside the screen to ensure direct contact. Cover the flat in padding and black fabric to protect the screen.

Weigh down the flat with something heavy.

After your exposure time is up, rinse the screen on both sides. The emulsion that was not exposed to light (because it was blocked by the opaque black areas of the Film Positive) will wash away. Wash the screen until there are very few white bubbles remaining. Store the screen on a flat surface to dry or use a fan.

When dry, screen is ready to proof.

InksInks

Consist of…Consist of…◦ Pigment--- provides the Pigment--- provides the colorcolor◦ Vehicle--- gives it “bulk”Vehicle--- gives it “bulk”◦ Solvent--- makes it flow, then evaporates, leaving the rest of the Solvent--- makes it flow, then evaporates, leaving the rest of the

ink behindink behind◦ Modifiers--- examples: thinners; phoshluorescents; puff agents; Modifiers--- examples: thinners; phoshluorescents; puff agents;

etc.etc.

Types of InkTypes of InkConventional– dry by air

Water basedSolvent based

Non-conventional– cured by “polymerization” Plastisol– cured with heat (325 degrees); used for absorbent

materials only (textiles); won’t work on paper, except for heat transfers.

UV (ultraviolet) inks– cured with UV light; for non-absorbent substrates such as vinyl, and coated papers. Quick, clean method.

Inks cont…Inks cont…Process inks vs. spot colors

Process inks- ________, ________, _______,________ combined to produce full color prints. Process inks have less “opacity.”

Spot color– one or more colors to improve appearance without expense of process printing (or could be a special color added to a process print)

Squeegees

Three main purposes

Force ink through mesh “Flood” stroke: purposeControl ink deposit

Squeegees cont…Squeegees cont… Recommended size: Recommended size: two inches wider than image width two inches wider than image width

(maximum)(maximum) Storage:Storage: Blade up Blade up Blades vary in:Blades vary in:◦ Material: vinyl or rubberMaterial: vinyl or rubber◦ Hardness: durometer rating (the higher the rating, the stiffer the Hardness: durometer rating (the higher the rating, the stiffer the

blade)blade)◦ Shape: Shape:

Squeegee cont…Squeegee cont…Clean-up

Water based ink- cleans up with Water!!Plastisols require __________ (paint thinner) or other specially

made ink cleaning solutions. Liquid (direct) emulsion– remove by degreasing first to get rid of

ink solvents left behind, then apply reclaimer.

Potential for Further Development

The main focus of further development lies principally in the plate making sector:

• The direct imaging of screens (computer to screen) will become more and more prevalent, especially in conjunction with rotary screen printing units for large print runs.

• The already available but still little used filmless stencil production with ink jet printing technology is of particular interest for large format applications. At approximately 600dpi, the resolution guarantees sufficiently good print quality even with color gradations.

Computer to screen for screen printing

• Computer to screen printing is the digital production of image carriers for screen printing in which the print image data, controlled directly via the computer, are output onto the stencil or screen. Most computer to screen systems work using the ink jet technology, in which either heated wax or ink is applied to the screen.

• First the screen must be lined with a closed layer/ emulsion (stencil material). The print image is applied to this coating using ink jet ink (as a film substitute). This is then followed by the usual exposure to cure the stencil material. The uncured ink-covered areas of the coating are then washed off with water. After drying, the stencil/ screen plate is ready for printing.

Different type of screen printing process

Modern screen printing process

Terms to Know!Terms to Know! Scum:

Unexpected image which comes from stencil or plate.

Haze: Generalized faint staining of screen mesh caused photo

stencils, screen filters, printing mixtures and varnishes: cf. ghost.

Fisheye: Unwanted open area in a photo stencil which prints with the appearance of the eye of a fish.

Margin: Perimeter of mesh adjacent to the frame of the screen: this non printing area is closed during printing, either temporarily or

permanently, to protect the mesh and to be used as a printing mix reservoir.

Digital positive: Positive created and output using a computer.

Artwork: A general term for photographs, drawings, and others materials prepared to illustrate printed matter.

Heat transfer paper: The substrate used in thermal transfer printing. The design is first printed on it with inks containing sublimely

dispersed.

Flood stroke: The squeegee motion that deposits a thick layer of ink on top of the screen printing screen under light pressure. The excessive ink prevents the image areas from drying

between printing strokes.

Mesh aperture: The space between the woven threads of screen printing

fabric, through which the ink passes during printing.

Screen opener:

A chemical, usually in aerosol spray from, used to clear dried-in areas of a screen printing stencil.

Dark reaction:

In an unexposed light-sensitive emulsion or coating, the sloe chemical change that occurs when the material is stored in an unlighted area.

Mesh?Stencil?