Extended Gamut Printing Article
7
Extended Gamut Printing in Flexographic Packaging Printing Wayne Peachey, SGS International The UK is known for many great things… The Beatles, London, the Royal Family, red buses, fantastic green countryside, a rich history. It is not known for it’s fine weather and living next to the Atlantic Ocean means the country experiences more than it’s fair share of rain! However every British male has one item in his wardrobe, a Hawaiian shirt! This is the type of shirt with bright colours, pictures of palm trees, parrots, fish, and when the sun eventually appears and warms the land, the British male knows it is time to wear his bright shirt and enjoy the sunshine as if he were on the beaches of Honolulu! Most Hawaiian shirts in the UK are more than ten years old, they never wear out, they are seldom worn thanks to the British climate! It could be said that Extended Colour Gamut is the Hawaiian shirt of printing. Every few years there is a buzz, with new products and new ways of working. Tests are set up and run on presses, lots of excitement ensues, and then ECG is put away to the back of the printing wardrobe for a few more years. So it may seem. However, the benefits of ECG have been realized in many markets and it is almost an industry secret that many presses are running 24/7 with just one set of inks, with minimal press changeover times, minimal ink inventory, and hugely increased press uptime. Extended Colour Gamut Printing has many different names, such as Multicolour Printing or trade names such as Opaltone. At its core the technology uses a standard set of colours in the printing press that seldom change. When a spot colour is needed (eg. Pantone 485), a mix of two or three colours will be used to get ‘very close’ to that specific red. WHICH ADDITIONAL COLOURS ARE USED? Typically CMYK is used, plus two or three colours that help to significantly increase the achievable colour gamut. Cyan, Magenta, Yellow and Black normally form the basis of the colour set. Then two or three colours are added and these never change in the press, so initial choice of the additional colours is really important. Normally colours much brighter than CMY are added, and these are typically chosen from Orange, Red, Violet, Blue, Green. So the ECG set could be (for instance) CMYKRGB, CMYKOGV, CMYKRB, CMYKOG, CMYKOV etc.
-
Upload
wayne-peachey -
Category
Documents
-
view
132 -
download
0
Transcript of Extended Gamut Printing Article
ExtendedGamutPrintinginFlexographicPackagingPrintingWaynePeachey,SGSInternationalTheUKisknownformanygreatthings…TheBeatles,London,theRoyalFamily,redbuses,fantasticgreencountryside,arichhistory.Itisnotknownforit’sfineweatherandlivingnexttotheAtlanticOceanmeansthecountryexperiencesmorethanit’sfairshareofrain!HowevereveryBritishmalehasoneiteminhiswardrobe,aHawaiianshirt!Thisisthetypeofshirtwithbrightcolours,picturesofpalmtrees,parrots,fish,andwhenthesuneventuallyappearsandwarmstheland,theBritishmaleknowsitistimetowearhisbrightshirtandenjoythesunshineasifhewereonthebeachesofHonolulu!MostHawaiianshirtsintheUKaremorethantenyearsold,theyneverwearout,theyareseldomwornthankstotheBritishclimate!ItcouldbesaidthatExtendedColourGamutistheHawaiianshirtofprinting.Everyfewyearsthereisabuzz,withnewproductsandnewwaysofworking.Testsaresetupandrunonpresses,lotsofexcitementensues,andthenECGisputawaytothebackoftheprintingwardrobeforafewmoreyears.Soitmayseem.However,thebenefitsofECGhavebeenrealizedinmanymarketsanditisalmostanindustrysecretthatmanypressesarerunning24/7withjustonesetofinks,withminimalpresschangeovertimes,minimalinkinventory,andhugelyincreasedpressuptime.ExtendedColourGamutPrintinghasmanydifferentnames,suchasMulticolourPrintingortradenamessuchasOpaltone.Atitscorethetechnologyusesastandardsetofcoloursintheprintingpressthatseldomchange.Whenaspotcolourisneeded(eg.Pantone485),amixoftwoorthreecolourswillbeusedtoget‘veryclose’tothatspecificred.WHICHADDITIONALCOLOURSAREUSED?TypicallyCMYKisused,plustwoorthreecoloursthathelptosignificantlyincreasetheachievablecolourgamut.Cyan,Magenta,YellowandBlacknormallyformthebasisofthecolourset.Thentwoorthreecoloursareaddedandtheseneverchangeinthepress,soinitialchoiceoftheadditionalcoloursisreallyimportant.NormallycoloursmuchbrighterthanCMYareadded,andthesearetypicallychosenfromOrange,Red,Violet,Blue,Green.SotheECGsetcouldbe(forinstance)CMYKRGB,CMYKOGV,CMYKRB,CMYKOG,CMYKOVetc.
ExtendedcolourgamutsvsCMYK,withPantonelibraryoverlaidWHICHSETGIVESTHEGREATESTCOLOURGAMUT?Colourgamutisthesizeofthecolourspacethatcanbeachieved,whencalculatedasanL*a*b*colourspace.TheadditionofOrange,GreenandVioletprovidesthegreatestcolourspace(dependingonthecolourschosen),howeverwhenthesearemixedonpress(usingscreening)theycanpresentmoreregistrationchallengesthancoloursetssuchasCMYKRB.RedandBluearethemostcommonspecialcoloursused.UsingCMYKRBsmallbluetextcanbeachieved,howeverinaCMYKOGVcoloursetthesmallbluetextwouldneedtobemadeupoutofCyanandViolet,whichcouldpresentaregistrationchallenge.Ifcolourgamutisapriority,thenthebrightestcoloursetwouldbeimportant.Ifacustomers’specificbrandcolourismoreimportant,thenyoumaynotwanttouseacoloursetthatgivesyoubetterregistrationandbettercolourconsistency.
Soyoucansee,dependingonyourdesignneeds,youcanchoosethecolourcombinationthatisthebestfit.INPRACTICE,WHATDOPRINTERSUSE?Somecustomershavespecifiedacolourset,suchasCMYKOGV.Theythenrequesttheirprintersstandardizetothis.Othercustomersjustwantgoodqualityprint,butatareasonablecost.Thereforetheyarehappytoswitchtheirworktoaprinters’ownECGworkflow,reapingsavingsinprintingcosts.CMYKRBisverypopular,asRedandBlueareusedofteninpackagingprinting.Greencanbeadded,howeverunlessyouwantyourimages(eg.Lettuce)tobeperfect,greendoesn’taddasmuchtotheimpactofthework.PrinterssometimesadoptaCMYKRGB(forinstance)workflow,andthenonlyusegreenifabsolutelyrequired.ToachievePantonecoloursasaccuratelyaspossible,acoloursetofCMYKOGVwouldberequired.Testingwithaninkcompanywouldbethebestwaytoachievethelargestcolourgamut,andthereforethebestcolourmatchtoasmanyPantonecoloursaspossible.SOBRIGHTERCOLOURSELLS?Yesitdoes,ifaproductpackageisbrighterthanitscompetitorsthenitcanattractshoppers’attention.HoweverECGcansometimesfailifthecoloursaretoobrash,oriftheproductimagesarenotrealistic,orifthecoloursarenotconsistent.WHATARETHEPRACTICALBENEFITSINTHEPRESSROOM?Atypicalflexographicinkroomwillcontainmanyhundredsofpartly-usedinkpails.Thesewillbeleftoverfrompreviousprintruns,andmaybeusedinthefuture.Butnormallythesejustsitaround,andiftheyareusedtheirconditioncanbeanunknownandsoleadtopressdowntimeastheink/solventsmixisbalancedforthejobinthepress.WithECGyoujusthaveseveninks,pluswhite.Whenyoufinishonejobandstartanother,youdonotneedtoreturntheinktotheinkroom,mixupfreshcolours,andthenputthoseinthepress.
Alargeinkinventorycanbereducedtojustsevencolours!Onpressyouwouldremovetheplates(ontheirprintingsleeves),installthenewprintingsleeves,andthenstartupthepress.Thesameinksareused,andsootherthansomeminoradjustmentsthejobisreadytorun.Thesavingsaredependentonspecificsituations.Forinstanceifyoualreadyrunjobsfor24hoursormore,youmaynotseeahugeimprovementinpressuptime.Ifyourtypicalrunsareanhourortwo,andthenyouhavetwohoursofpressdowntimewhilethepressiscleanedupandtheinkschanged,pluscolourmatched,youwouldseesignificantsavings.Inthemostextremecases50%to100%morepressuptimecanbeachievedusingECG.SomecustomersarefullyawareofthepotentialsavingsandarehappytoencourageprinterstomovetoanECGworkflow.Forinstancesupermarketsprintalargerangeofitemsforwhichqualityneedstobeacceptable,butcostshavetobeabsolutelyminimal.ManyintheUKhaveswitchedovertoECGtorealizethecostbenefits,notnecessarilyforthebrightercolourgamutthatcancreatemoreimpactwithinimages.Changingafourcolourjob(forinstance)tobeasevencolourjobdoesnotsimplifyanything,itcancreateadditionalcost.Also,runningECGonlypartofthetimecanbeadisruption.Printerswhotakethisonboardtypicallydedicateoneortwopressestothistypeofwork,andprintothertypeswithtraditionalprintingtechniques.WHATABOUTCOLOURSEPARATION,COLOURPREDICTIONANDCOLOURMATCHING?ThankstomodernprepresscolourprofilingtechniquesasevencolourECGprocesscanbeprofiledaseasilyasafourcolourprocess.Specialsevecolourtargetsareprinteronpressandtheresultingprofiles(createdusingXrite’sProfilemakerorsimilar)canthenbeusedinconjunctionwithacolourripsuchasGMG.SpotcolourscanthenbepredictedusingtoolssuchasXrite’sColorPicker,whichwillprovideabest-colour-breakdownandapredictionofDEcolouraccuracy.
XriteColorPicker,matchingPantone660basedoncolourprofileinformationSpotcolourscanalsobeshownasalarge‘swatchbook’,sothatdesignerscanselectcolourswithconfidence.
AnexampleECGcolourswatchbookthatcanbeprintedoutandsharedwithdesignersColourseparationofimagesislessstraightforward.ItisoftenasubjectivedecisionwhetheraCMYKimageactuallyneedstobeseparatedintosevencolours.Skintonesdonotnormallybenefitfromextracolours,butiftheimagecontainsvegetables,forinstance,theadditionofgreeninlettuceandredinpepperscanreallyimprovetheimage.Thereforecolourseparationcancostalittlemore,duetotheadditionaltimeinvolved.WHATABOUTPLATEANDPRESSTECHNOLOGIES?Inthepastflexographystruggledtoachievegoodsoliddensity.Thereforewhenadarkspotcolourwasused,aheavyaniloxwouldlaydownlotsofink.
ModernprintingmeansthatHDflexoplates,usingsolidscreeningtechniques,canachievedensitiesthatcompetewithlithoandgravure.Thesetypesofplatecanbematchedwithlowvolumeaniloxes(matchedwithhighqualityinks)sothatmidtonetonevaluesarekeptundercontrol.Oncethisisachievable,ECGcanbeconsidered.ECGreliesongoodconsistentresults,andgoodregistration.Repeatabilityisthekeyandjobscanthenrunoneaftertheother,withtheminimumofpressadjustmentsbetween.Thebenefitstotheprinterarethattheirpressescanachievegreateruptime,asno-onepaysforthepresstimewhenitisnotrunning.Thebenefitstothecustomerarealowercostproduct,butwiththesameorhigherquality.WHATABOUTOTHERPRINTPROCESSES?LithohasadoptedECGforyears.Thegreatbenefitisthattheplatesarerelativelyinexpensive,andsojobscanberunincombination(eg.Perhaps24differentdesignsononesheet),withlotsofspotcoloursrepresentedasECG.ScreeningisveryfinewithLithososcreenedspotcoloursarenotnoticed,andregistrationistypicallygoodwithLitho,sothefitbetweenECGandLithoisverygood.Gravurecouldrealizesomeofthebenefits,butthefactthatcylindersaredeliveredtothepresscompletewiththeirinktraysmeansthatthechangeoverdelaysarenotsoprevalent.Possiblygravuremaysufferfromeverycolourbeingscreened,andsosufferwithmoireissues.IhavenotpersonallycomeacrossgravureprinterswhouseECGbutnodoubtsomeoneouttherehasfoundthesametypesofbenefitsasrealizedinFlexo.ExtendedColourGamuthasaplaceinprinting.IthasastrongalthoughdiscreetfootholdinflexographybutonethatIbelievewillgrowduetopricepressuresandduetoit’sflexibility.It’sawin-winformanycustomersandprintersandonethatshouldnotbeoverlooked.SUMMARYOFBENEFITSQuality Enhancementofimages/Additional&morevibrantcolors/Increasedtonalrange/Increased“POP”/ConsistencyofprintprocessTime&CostMake-ReadyTime&MaterialReduction/Inksarealwaysinthepress/Printrotationspre-determined/Ink“Wash-ups”notrequiredaftereveryrunInk6-7basecolors/Nospotcolors!/Reducedinkinventory/Reductionofinkmanagementcosts/Nospecialcolormatching/Greaterinkbatchconsistency/Leveragedinkspendfor6-7basecolorsPrintMix
Commoninkcolorsenablecombinationprintforms/Brandfamiliescanbegangedtogetherinacombinationrun/Reducedfinishedgoodsinventory
