Screen E-Book (.PDF) - MacDermid Autotype

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Getting the right exposureThere is always a compromise between exposuretime and achievable resolution becausethere is always some scatter withinthe system. As you increase exposure tocreate a harder stencil you automaticallystart to reduce the resolution.Comparing exposure times with white andanti-halation dyed meshWhite mesh transmits and scatters light,yellow and orange mesh absorb the wavelengthsneeded for the crosslinking reaction,but scatter far less of the light.This means that dyed meshes require longerexposures (up to 4x for some yellowmeshes) but give better resolution anddefinition. Light scatter increases withmesh count and exposure time.This makes using dyed mesh particularlyimportant for fine detail resolution on finemeshes.Poor contact with positiveThe contact between positive and stencilshould be as perfect as possible, inadequatecontact results in light undercutting,more so when combined with poor lightgeometry.66
Here’s what can happen if the positive isplaced the wrong way up. Light undercuttinghas resulted in loss of resolution.UV lightUV lightSimilarly, poor contact caused by dust cancause noticeable blemishes in half tones.Microscope picture showingblemish in what should havebeen an even tone in the centre67
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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
Page 15: This is the single most important f
Page 18 and 19: When I first pointed this out to my
Page 20 and 21: The Theory Bit20Why is the 1-2-3 so
Page 22 and 23: The mesh does the meteringThe 1-2-3
Page 24 and 25: This gives us the ‘real’ TIV fo
Page 26 and 27: simple, in-control process.Years of
Page 28 and 29: The Optional Theory28At the shear r
Page 30 and 31: I’ve come across examples in all
Page 32 and 33: The Optional TheoryOur 50µm line b
Page 34 and 35: oughness can slow slumping; it prob
Page 36 and 37: The Optional TheoryThe exact part o
Page 38 and 39: atches of the ‘same’ mesh. My f
Page 40 and 41: The Optional Theory40The industry r
Page 42 and 43: the screen frame itself to compensa
Page 44 and 45: Print Faults - Making and fixing th
Page 46 and 47: Print FaultsThey include tape marks
Page 48 and 49: Wrong ink - Too much viscous drag (
Page 50 and 51: DustPrint FaultsWe threw some dust
Page 52 and 53: What’s the best order to print yo
Page 54 and 55: Colour shifts54high-frequency (non-
Page 56 and 57: We formed our own (subjective) opin
Page 58 and 59: And the winner is...Colour shifts58
Page 60 and 61: Getting the right exposureAnna Harr
Page 62 and 63: Getting the right exposureThe light
Page 64 and 65: 3/4 full exposureEFFECTS: Emulsion
Page 68 and 69: Undercutting from a rough stencilSo
Page 70 and 71: Getting the right exposure(or numbe
Page 72 and 73: Solving problems in the real worldA
Page 74 and 75: Solving problemsThe simple act of r
Page 76 and 77: Emulsion coatingThe advice about cl
Page 78 and 79: Solving problemsA quick tip to help
Page 80 and 81: 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
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grid) in a conventional set that wa
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Moire, causes and cures118what this
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Arguably the skipping takes place p
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Moire, causes and curesSummaryAs Ma
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MoiréDescriptionAn unexpected patt
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Problem solving GuideCause1. The mo
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Dark spots / HickiesDescriptionDark
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Problem solving GuideTechnical refe
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6. Substrate unstable.7. Changes in
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Glossary of terms used in this eBoo
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Glossary136Moiré amplitudeThe ampl
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A Macdermid Autotype HowTo eBookEdi
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