Screen E-Book (.PDF) - MacDermid Autotype

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6. Substrate unstable.7. Changes in temperature during stencilprocessing.8. Changes in humidity during stencilprocessing.Technical referenceSee ‘Optional theory’ chapter and ‘Problemsolving in the real world’ chapter.Solution1. Reduce off contact2. Reduce squeegee pressure, using a lowEOM stencil minimises the need for highsqueegee pressure.3. Use a larger screen for the job4. <strong>Screen</strong> should be less than 1N/cm differencein mesh tension.5. Stainless steel mesh gives minimumstretch.6. Condition the substrate before use7. Always expose and print the stencil at aconstant temperature and humidity.Ink SievingDescriptionStencil open but ink not passing through.CauseMesh too fine to allow all the ink particlesto pass through.Technical referenceSee ‘Print faults and fixing them’ chapter.SolutionUse coarser mesh. Capillex CX will allow acoarse mesh to be used whilst giving a lowprofile, fine resolution stencil.CobwebbingDescriptionRandom trails of ink spreading from theimage.CauseStatic.Technical referenceSee ‘Problem solving in the real world’chapter.132
Solution1. Earth the press.2. Raise the print room humidity.3. Use deionised air reduce static on thesubstrate.Poor cure of UV inkDescriptionPoor cure of UV ink generally results inpoor adhesion. Ink not adhering well tothe substrate can be seen as reticulation orwrinkled surface. Adhesion can be testedby ‘finger nail scratch and tape test’ ‘crosshatch and tape test’ or ‘thumb twist’.Cause1. UV curing unit not working correctly.2. UV ink layer too high.3. Substrate and ink combination are notcompatible.Solution1. Check lamp, power setting, lamp assemblycleanliness, bulbs and belt speed.2. Check that the ink layer is not too high,check the mesh count and use a low EOMstencil.3. Ensure that the ink and substrate arerecommended for use with one another.4. Ensure that the substrate is not porousto the ink.133
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HowHow to be agreat ScreenprinterEd
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About this eBookI’m passionate ab
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06Table ofContents07 The Theory Bit
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The wrong way: a strong-deep flood.
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why a light flood is recommended so
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This is the single most important f
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When I first pointed this out to my
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The Theory Bit20Why is the 1-2-3 so
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The mesh does the meteringThe 1-2-3
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This gives us the ‘real’ TIV fo
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simple, in-control process.Years of
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The Optional Theory28At the shear r
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I’ve come across examples in all
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The Optional TheoryOur 50µm line b
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oughness can slow slumping; it prob
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The Optional TheoryThe exact part o
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atches of the ‘same’ mesh. My f
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The Optional Theory40The industry r
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the screen frame itself to compensa
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Print Faults - Making and fixing th
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Print FaultsThey include tape marks
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Wrong ink - Too much viscous drag (
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DustPrint FaultsWe threw some dust
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What’s the best order to print yo
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Colour shifts54high-frequency (non-
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We formed our own (subjective) opin
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And the winner is...Colour shifts58
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Getting the right exposureAnna Harr
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Getting the right exposureThe light
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3/4 full exposureEFFECTS: Emulsion
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Getting the right exposureThere is
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Undercutting from a rough stencilSo
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Getting the right exposure(or numbe
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Solving problems in the real worldA
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Solving problemsThe simple act of r
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Emulsion coatingThe advice about cl
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Solving problemsA quick tip to help
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stencil causes a thick edge needed
Page 82 and 83: Solving problemsThis screen-shot fr
Page 84 and 85: A modest Rz gives amodest absolute
Page 86 and 87: Solving problemsThe root cause of n
Page 88 and 89: Now the ink fully fills the extra s
Page 90 and 91: Solving problems90Stencil X gives b
Page 92 and 93: Moiré, causes and curesSteven Abbo
Page 94 and 95: Moire, causes and cures94fluential
Page 96 and 97: Figure ii. The overlayedpattern fro
Page 98 and 99: Moire, causes and cures98Causes and
Page 100 and 101: 2 15° moiréIt’s an unfortunate
Page 102 and 103: Moire, causes and cureson top of an
Page 104 and 105: Ideal. Find a RIP with an option fo
Page 106 and 107: Moire, causes and curescan’t pick
Page 108 and 109: frequency tend to have a lower ampl
Page 110 and 111: Moire, causes and curesis a half-tr
Page 112 and 113: Incidentally, note that the ratio o
Page 114 and 115: Moire, causes and cures114So, surpr
Page 116 and 117: grid) in a conventional set that wa
Page 118 and 119: Moire, causes and cures118what this
Page 120 and 121: Arguably the skipping takes place p
Page 122 and 123: Moire, causes and curesSummaryAs Ma
Page 124 and 125: MoiréDescriptionAn unexpected patt
Page 126 and 127: Problem solving GuideCause1. The mo
Page 128 and 129: Dark spots / HickiesDescriptionDark
Page 130 and 131: Problem solving GuideTechnical refe
Page 134 and 135: Glossary of terms used in this eBoo
Page 136 and 137: Glossary136Moiré amplitudeThe ampl
Page 138: A Macdermid Autotype HowTo eBookEdi
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