Screen Printing

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

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

Applications for Screen Printing:

PostersPlastic bottlesDrinking glassesSoda bottlesMirrors, metal surfacesWoodTextilesPrinted circuit boardsProduct displaysVinyl binders

Advantages of Screen Printing

Images can be printed on a wide variety of substratesThe production process is relatively easy.Capital expenditures are low compared to other printing processesImages can be printed with glitter, flock, and other decorative finishes.The ink film is very resilient due to the extreme thickness of the ink deposit

Disadvantages of Screen Printing

The process is usually limited to flat, relatively thin substrates, such as paper, metal, or plastic.Rate of production is slow.Ink mileage is poor.Excessive drying times may be necessary.Details and fine line images may be difficult to print.

Basic Equipment for Screen Printing:

Screen fabricFrameStencilInkSqueegeeSubstrate

Squeegee blades

Square edged: flat surfaces and general purpose printingSquare-edge with round corners: Gives extra-heavy ink deposits on flat substrates. Used when a light color will be printed on a dark substrate.Round-edge: Used primarily in textile printing where an extra-heavy ink film is required.Single-sided beveled edge: Used for printing on glass.

Squeegee Blade Shapes (con’t.)

Double-sided beveled edge with flat point. Used for printing on ceramicsDouble-sided beveled edge. Used for printing on cylindrical objects such as bottles and containers.

Squeegee Blade Shapes

Screen Inks

Water BasedOil Based

Screen Printing Solvents

WaterMineral Spirits (or mineral spirits substitute)

Screen Frames

WoodAluminum SteelPlastic

Screen Fabrics

Filaments are threadsMultifilament – sewing thread exampleMonofilament – fishing line exampleMesh count = number of threads per linear inchThe higher the mesh count, the better the reproduction of fine details.

Mesh Count (con’t.)

Multifilament ranges from 5 to 25. Multiply the digit by 10 to get an approximate number of threads per linear inch.

Monofilament are specified by actual number of threads per linear inch.

Fabric Strength

XXXXXX

Most screen printers select XX multifilament or T- monofilament.

Types of Fabric

Silk - most expensiveOrgandy - cheapestPolyester - middle of the roadNylon - used for non-flat substratesMetal Mesh - most durable, but expensiveMetalized Polyester - durable but not too expensive

Fabric Attaching and Tensioning

StaplingCord and GrooveMechanical ClampingAdhesive Bonding

Measuring Fabric Tension - tensiometerFabric Treatment - abrading

Stencils

Knife-cut stencils – Paper stencils, water-soluble stencils,lacquer-soluble stencils

Photographic Stencils – indirect, direct, direct/indirect

Screen Printing at Pope

Aluminum Roller FramesXX, monofilament, polyester meshPhotographic direct emulsionPlastisol (oil based) inkMineral spirits substituteEmulsion removed and screen cleaned with special solvents and water.