Offset Printing

Offset printing

it is a form of Flat printing. It involve the transfer of a flat image from the printing on the substrate, eg. paper.  This operation is carried out with cylinder coated with an intermediate rubber blanket hereinafter.

Offset printing can be divided into:

  • Sheet offset printing – in this type of printing, offset sheet become substrate of printing inks.
  • Offset spiral – in this case the substrate is a roll of paint slip
  • Coldset – offset “cold” (fixing the paint soak into paper )
  • Theatset – offset “hot” (fixing the paint soak into the paper and evaporation at high temperature ) coverd with paint. The paper ribbon passes through the heated to a high temperature drying tunnel.

Coldset and heatset

In general Coldset and Heatset  are used for high volume printed materials such as newspapers, magazines, phone books, ect..  The substrates of this kind of printing is calendered paper and coated paper. 

Water offset

As the name suggest is associated with printing using the dampening solution. In classic offset or water offset  on the water surface located are points hydrophilic  and hydrophobic places. Between this two elements or aqueous solution environment  and the environment of oil paint is mutual repulsion.  The most important thing in this environment is reaching the stability, water – paint.  Moisturize solution is about  85% - 95% water. Another substances which are add to aqueous solution is isopropyl alcohol (IPA). It should be noted that there is general trend to reduce IPA for buffers.

 Waterless offset  

The form of offset printing without using aqueous solution. This form of printing uses special paints characterized high surface tension and special printing plates – silicon forms. Positive feature waterless printing is the lack of problems of contact aqueous solution with paint printing (paint emulsification) and ground. (surface moisture). Waterless printing also allows for thicker, (ie more then 3.5 microns) imposition of paint then in classic offset.  This is possible thanks to special printing form similar to copper–plate printing.  Because of the high cost of waterless printing and technological problems, occupy small area of market.

The cause mold offset - is the act of removing a layer of non-printing copying of forms, by dissolving them in the developer.

History of the offset  

Offset printing was born in XVIII century, in the time of discover a lithography, new kind of printing technique.  Sons of some Royal Theater actor studied a law, imposed to him by the father.  But with his death, Aloisy interrupted studding and want to join in adult life followed in his footsteps  he decided to become a actor.  It soon became apparent that he was bad actor but a great writer. In spite of fact not too many published works, gained a lot recipient.  In that time cost of printing was high, so distributions of his works was miserable.  In order to speed up the publication of materials has often been in the printing. In time, said that printing is no philosophy. He acquired  the copper plate which then began to engrave.  The work not the easiest and required preparation picture on the disk in a way that was a mirror reflection.  Some day mother asked for prepare list of things to washing.  Aloisy didn’t have a pan, so he wrote the list on the stone using soot mixed with soap. Suddenly he saw that the places cover up with mysterious substance didn’t  absorb water, but paint clanged to it.

After that event Aloisy made his painting on the stone, wetting the surface with water,  imposing paint.  And so was matrix. Another successful Senefeldra experiment was transferred drawing on special paper onto a limestone slab.  Effect of this was possibility of makes a drawing right-clearly, possibility of resume order  and exactly copy the same order on the same plate. Aloisy became a father of lithography and patented his own invention.

At the beginning lithography spread quickly, but she had a serious flaw.  Did not allow for high speed printing because of flat stone slabs.  Lithography slowly gave way to letterpress  where plate gave a new shape of a cylinder. The new plates are formed of zinc and aluminum. It was set up on special cylinder and in that way transferred on the paper.  The disadvantages of this solution is directly contact slab with paper. The result of this was quickly wiped of picture. This model of print never disseminated.

An American producer of paper printed by accident with gum. Employee inadvertently didn’t plant the paper under the gum. After the rebound rubber paint on it turned out that the drawing carried by rubber is clearer and cleaner. These were the beginning of moving work through the rubber on paper. Printing indirectly contributed  to extend the life of plates and gave birth a new technology.
Photography used in lithography caused that invent of appropriate glass plates through which taking pictures obtained raster. Color Photography launched in color offset printing with process inks. 

Making printing plates on an industrial scale has opened the door to the path of development of offset printing.


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