Reproducing an Image
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Reproducing an Image

 

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  • Reproducing an Image

 

 

 

 

 

 

 

 

 

To produce half tone or line blocks photocopying copy is done by fixing the original in front of the camera. Copy can only be enlarged or reduced in proportion by the camera and, therefore, all originals must reduce or enlarge by a previously decided proportion before the copy goes to camera.

  1. When a sensitised film or plate is exposed to light and then developed, the areas affected by light appear dense on the negative and the areas not affected by light remain transparent.
  1. The developed film or plate is a negative or, in other words, the complete opposite of the original.
  1. In block making the negative has to be printed on to a metal plate to form a printing surface, which in letterpress printing, has to be the reverse of that required when finally printed on a paper. A prism placed in front of the camera produces the negative in which the image appears the same way round as the original. This provides the required effect for relief printing.
  1. The negative is now ready for use and is printed down on to a smooth metal surface, which normally is made of zinc, (hence the trade name zinco). The area is coated in light sensitive material which is then exposed to light through the negative. The light hardens the light sensitive material and when developed the unhardened material washes away. The light hardened image is then inked up and dusted with an acid resisting powder. The zinc is then etchedand then the acid bites into the metal which has not been protected by the acid resisting material, this you obtain a printing surface in relief which is known as a zinco.