VC 246 :: Week 01 1 of 6 28 September These carriers often take the form of printing plates.

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1 VC 246 :: Week 01 1 f 6 28 September 2017 week::ne Printing Techniques and Prcesses Tw Basic Printing Techniques Printing Presses Use an image carrier t prduce images. These carriers ften take the frm f printing plates. Image is static the last print is exactly the same as the first. Ideal fr prducing large quantities f a publicatin. Examples: Offset printing, letterpress, screen printing, gravure & flexgraphy. Printers D nt use an image carrier. Image is dynamic each impressin can be different frm the next. Allws fr variable data printing that is, the changing f cntent in a publicatin during printing. Think mail merge n a large scale. The term digital printing generally uses the techniques fund in printers, but des s at a cst and speed that cmes clse t printing press methds. Examples: Laser printers (xergraphy), ink jet printers, and digital presses. Xergraphy Prcess The electr-phtgraphic prcess. Used in laser printers and cpiers. Uses tner with an electrical charge t create the image. Des nt use an image carrier. Unlike ink, tner sits n tp f the paper. An electrical charge is applied t a cnductr drum. A laser remves the charge frm the nn-printing areas f the drum; Tner (charged in ppsite f the drum) adheres t the charged areas. The tner is transferred t the paper, which als has the same (but mre pwerful) charge applied t it. Tner is bnd t the paper using heat and pressure applied by rllers in the fuser.

2 VC 246 :: Week 01 2 f 6 28 September 2017 Ink Jet Used In Prcess Drp-n-demand prcess. Ink is absrbed int the paper. Requires special paper t achieve the best quality. Des nt use an image carrier. Very expensive cmpared t ther printing methds. By sme calculatins, ink fr the cheap hme printers csts $3,000 a galln. Hme and ffice printers. Small-run jbs where quality is critical. Large frmat printing & digital prfs. Prduct labels where infrmatin changes frm print-t-print (addresses, expiratin dates, etc.). In piezelectric ink jet printers, the vibratin f crystals causes ink t sht nt the paper. In thermal ink jet printers, ink is heated very quickly, which causes a vapr bubble t frm and sht ink nt the paper. Dye Sublimatin Prcess AKA: Dye thermal transfer printer One f the few true cntinuus-tne printing technlgies. Can prduce true phtgraphic-quality images. Is nt as gd at printing line art images and text. Is very expensive by any measure. Can print n many types f paper. Nt used as much anymre ink jet printers surpass it in quality in sme categries but sme new pht printers d use the technlgy. Uses a ribbn f clr wax r paraffin that is heated in the areas that transfer t the paper. Dye Sublimatin printers can vary the amunt f clr that can be placed at a specific area f the paper, creating true-clr images. Unused parts f the ribbn are wasted.

3 VC 246 :: Week 01 3 f 6 28 September 2017 Offset Printing Mst cmmn type f cmmercial printing. Is an indirect methd f printing. The image is transferred t a blanket befre being transferred t the paper (hence, the name ffset). Offset printing using an image carrier ne fr each clr ink. The mst cst-effective way t print runs f 500 r mre. Prints are generally made n ne side at a time. When an ffset press can print n bth sides at the same time, it is called perfecting. Print shps can purchase a perfecting unit fr their press, allwing fr duplex printing with just ne pass. Sheet-fed Offset Individual sheets f paper are fed thrugh the press. Offers the highest-quality printing f any printing methd. Line screens between lpi Thicker paper stcks High ttal ink limits, prviding fr high ink densities and rich-lking utput. Many ff-press finishing ptins. Gd fr runs between 500 and 50,000 units. Web-fed Offset Paper is fed t the printer n huge, cntinuus rlls f paper. Very fast printing. Offers OK-t-gd quality printing. Line screens between lpi Paper must be thinner Lwer ttal ink limits, smetimes resulting in washed-ut imagery Lts f nline (n-press) ptins, including flding, glue binding, and stapling. Often the piece that cmes ff the press is the finished prduct, including binding, cllating and stapling. One example is the newspaper. Gd fr runs between 15,000 and 1,000,000 units. Often a heater is used at the end f printing t reduce ink drying times. When a heater is used n a Web press, it s called heatset. On newsprint presses, n heater is used, which is called cldset. Printing Plates Printing plates are placed directly n the press and are the sle surce f artwrk in the printing prcess. Printing plates can be generated using a number f methds: Film Imagesetter: Film is prduced, then expsed t a metal plate using a phtgraphic prcess. Direct-t-Plate: A platesetter creates plates directly frm digital files. A laser is used t etch the plate directly frm the PstScript infrmatin sent frm the design applicatin. N film is made. Direct-t-Press: Printing plates are still made, but they are made directly n the printing press. There is n need fr film prcessing r a separate platesetter. (This term als refer t a printertype prcess f printing a digital file directly t a digital press). The Printing Unit The part f the printing press that transfers the ink t the paper. Cmpsed f three key cylinders: Plate, Blanket, and Impressin.

4 VC 246 :: Week 01 4 f 6 28 September 2017 Plate cylinder Blanket cylinder Impressin cylinder Hlds the printing plate. Ink is added t the plate and nly adheres t the printing surfaces. The ink is transferred frm the plate t a blanket made f rubber. The blanket is necessary since it cmes in direct cntact with the paper. Pressure is applied t it by the impressin cylinder. Presses the paper against the rubber blanket, keeping the paper as clse a pssible t ensure a clean transfer f ink. Printing Unit Diagram:

5 VC 246 :: Week 01 5 f 6 28 September 2017 Gravure Printing Prcess An ld but still used methd f printing. Expensive, but can pay ff with extremely-large press runs (100,000+) Gravure is always web-fed and is very fast. Similar t letterpress, but inverted. The ink fills the recessed areas f a printing frm, and is transferred directly t the paper frm the frm. This is different frm the indirect methd used in ffset printing. Flexgraphic Similar t letterpress, but mre mdern. Unlike Gravure, ink is placed n the raised surfaces f the printing plate. Can print n almst anything. Uses a rubber r plastic surface and a direct printing methd. Letterpress The riginal methd f printing. Uses differences in elevatin f the printing surce t prduce an image. The surce itself is inked between impressins. Can leave a physical impressin n the paper. Is still used fr specialty purpses (invitatins, business cards, etc.). Screen Printing Ink is pressed thrugh clth by a dctr blade as the blade is pulled acrss the fabric. Is very similar t printing with Spt clrs separatins are key here. Used in clthing (lg t-shirts in particular), prmtinal items, and ther specialty prducts. Chemeketa ffers a number f excellent curses in screen printing.

6 VC 246 :: Week 01 6 f 6 28 September 2017 Print Technique Cmparisn Frm A Guide t Graphic Print Prductin (page 329); Jhanssn, Lundberg, & Ryberg, Wiley & Sns.