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The most commonly used dot shapes used when outputting positives are: round, square, diamond, and elliptical. The most effective for silkscreen printing are the diamond and elliptical. Choice of Halftone Dot Shape Taking a closer look at the positive you will see that the dots are formed in regular rows, with each one "growing" outwardly from the centre. The size of each dot will depend on the lpi (lines-per-inch) setting selected when outputting the positives. The choice of dot shape for silkscreen printing is most important when looking at the midtone range of the finished print. At this point in the tonal range of the design, the dots begin to join up causing them to "bleed" into one another - this is known as dot gain. The amount of dot gain can also be effected by various print production conditions, to name a few: - incorrect screen exposure, the choice of ink and viscosity, squeegee pressure and shore. |
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| Bearing this in mind, it now becomes obvious that the round dot shape is not the ideal choice for silkscreen printing, as dot gain is very noticeable due to all four "sides" of the dots joining, creating acute angles between the connected dots which are easily "flooded" with ink. The resulting print will look a lot darker than the original design due to the loss of definition in the midtones. | ||
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ROUND HALFTONE DOT SHAPE
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| The diamond and elliptical dot shapes are more suitable to screenprinting because of the reduction of dot gain due to their design, which is narrow and long. As the dots "grow" from the centre out, they will begin to join along the edges of the longer axis first then the narrow edges will join. The angles produced by the connection of these shapes are obtuse making them less likely to be "flooded" with ink. The resulting print will have more definition throughout the tonal range. | ||
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ELLIPTICAL HALFTONE DOT SHAPE
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DIAMOND HALFTONE DOT SHAPE
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© 2002 UNIFLEX PLASTISOL PRINTING INKS. ALL RIGHTS RESERVED.
LIMITATIONS & CONDITIONS
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