<BODY> <P ALIGN="CENTER"><B><FONT FACE="Arial">OFFSET PRINTING UNIT AS A COATER</FONT></B></P> <BLOCKQUOTE><FONT FACE="Arial">Conversion of an old single colour sheetfed offset machine into an UV coating machine is the best possible option for a printer to adopt the new technology. There are several advantages of such conversions over traditional coater conversion, as mentioned below :</FONT></BLOCKQUOTE> <OL> <LI><FONT FACE="Arial">Offset machines are designed and fabricated to deposit or transfer a very thin ink film on to the substrates, It is in the range of two to three micron film thickness,which is nearly equal to a deposition of 2.5 GSM. So, the chances of unwanted higher deposition of costly UV coating are reduced, hence financial loss is negligible.</FONT></LI> <LI><FONT FACE="Arial">Control over film thickness or GSM deposition is more compared to coating machines.</FONT></LI> <LI><FONT FACE="Arial">In order to obtain a higher deposition, dampening system of the machine may be renovated to be used as a coating unit.</FONT></LI> <LI><FONT FACE="Arial">Automatic feeding unit ensures higher productivity.</FONT></LI> <LI><FONT FACE="Arial">Possibility to apply a sealing base coating (generally low cost aqueous formulation) with dampening unit prior to application of UV coating through inking unit of the press reduces coating cost in achieving higher gloss. (Before going for a long run job with this process, printers are recommended to test the success of it with their combination of paper/board, ink, varnish, machine and work environment.</FONT></LI> <LI><FONT FACE="Arial">Photopolymer flexographic plate can be used in place of lithographic plates for spot varnishing application.</FONT></LI> <LI><FONT FACE="Arial">It is easy to keep the glue flap unvarnished using photopolymer plates or pill of blanket</FONT></LI> </OL> <BLOCKQUOTE><B><FONT FACE="Arial">In converting a sheet-fed machine following points need to be considered:</FONT></B></BLOCKQUOTE> <OL> <LI><FONT FACE="Arial">Since the production speed is higher, the radiation source need to be of higher wattage to ensure proper curing of the coating.</FONT></LI> <LI><FONT FACE="Arial">Molleton cloth covers for dampening rollers should be removed.</FONT></LI> <LI><FONT FACE="Arial">Proper blanket (EPDM blankets) should be chosen for the UV material.</FONT></LI> <LI><FONT FACE="Arial">The soft rollers of the inking unit should be resistant to UV varnishes. Generally EPDM rollers serve the purpose.</FONT></LI> <LI><FONT FACE="Arial">Number of rollers in inking unit should be reduced to mini'mise the splitting of varnish film into thinner films. It helps in getting thicker deposition and reduces the maintenance cost of the machine as well.</FONT></LI> <LI><FONT FACE="Arial">To obtain thicker coating film deposition through dampening unit intermittent type dampen.</FONT></LI> </OL> <BLOCKQUOTE><FONT FACE="Arial"><B>Conclusion:</B></FONT></BLOCKQUOTE> <BLOCKQUOTE><FONT FACE="Arial"> The UV varnishing system is the next generation solution to the ever-demanding speed of the printing and finishing process. With proper handling of materials, logical analysis of specific requirement and implementation, the technology has the capability to yield most wanted extra profit for the printers On the other hand, it can be a powerful tool for the designers in giving shape to their imagination with wide range of finishes, better colour gamut (for UV inks) etc. </FONT></BLOCKQUOTE> </BODY>