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Screen Printing

Screen Printing. Main Advantages. Can be printed on a wide variety of materials. Preferred over other methods, because of its low cost. Frames. Materials Wood– less expensive, warps or rots faster Aluminum– more expensive, durable Sizes Labeled according to I.D. (inside dimension)

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Screen Printing

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  1. Screen Printing

  2. Main Advantages • Can be printed on a wide variety of materials. • Preferred over other methods, because of its low cost.

  3. Frames • 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.

  4. Fabrics • 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

  5. Fabrics cont… • Two general types • Multifilament: tiny strands twisted together • Includes: polyester and silk • Good for film stencils (like amber film)—sticks to it better • Monofilament: (mono= one) single strand of thread • Good for liquid emulsion • Includes polyester; stainless steel • Good for fine detail; easier to clean than multifilament

  6. Fabrics cont… • Colored Fabrics: used to reduce unwanted glare during exposure, called “halation’s.” Halation’s cause distortion around edge of images.

  7. Stencils (Two Types) • Non-photographic: hand cut (i.e. amber film, or paper) • Photographic: (light sensitive) photoemulsion (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 scumming (an almost invisible film forms on stencil from the still soft emulsion running across screen as it dries)

  8. Exposure Process cont… • Pinholes– tiny openings in the stencil caused by: • Poor positive (not opaque enough) • Too thin of emulsion • Screen poorly prepped • Bubbles in emulsion (do not shake!) • Dirt on exposure unit glass

  9. Exposure Process cont… • Positive: Must be made right reading with high density to UV-A illumination • Screen preparation: degreaser is applied to remove any oils or solvents from the fabric so emulsion will go on without flaws. • Exposure times vary with: • Thickness of emulsion (also how many coats) • Mesh count • Type of exposure unit

  10. Inks • Consist of… • Pigment--- provides the color • Vehicle--- gives it “bulk” • Solvent--- makes it flow, then evaporates, leaving the rest of the ink behind • Modifiers--- examples: thinners; phoshluorescents; puff agents; etc.

  11. Types of Ink • Conventional– dry by air • Water based • Solvent 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.

  12. 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)

  13. Squeegees • Three main purposes • Force ink through mesh • “Flood” stroke: purpose • A. ______________________ • B. ______________________ • Control ink deposit: • Low angle=_______________ • Slow speed=______________ • More pressure=____________

  14. Squeegees cont… • Recommended size: two inches wider than image width (maximum) • Storage: Blade up • Blades vary in: • Material: vinyl or rubber • Hardness: durometer rating (the higher the rating, the stiffer the blade) • Shape:

  15. 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.

  16. Terms to Know! • Trapping: • Off-contact: • Halations: • Scumming: • Haze: • Platen:

  17. Terms to Know cont… • Substrate: • On-contact: • Opacity: • Reclaim: • Register guide: • Durometer rating:

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