White paper l 31 January 2013 I LUX Membrane 200LUX with Membrane 200:Engineered Surface Roughness ImprovesSolid Print Quality
2White paper l 31 January 2013 I LUX Membrane 200EXECUTIVE SUMMARYMacDermid LUX membrane and exposure technology delivers aunique flat-topped dot shape that improves print quality andconsistency, while delivering exceptional versatility for theplatemaker.Using LUX Membrane 200, we can emboss an engineeredsurface texture into plates made with LUX, which allows solid inkdensity (SID) to be increased and mottle to be decreased. Thiseffect is evident in plates processed by both solvent and Lavathermal processing methods.The use of Membrane 200 is a quick and effective means ofimproving solid print without the need to add special screening toartwork, while retaining all the advantages of the LUX dotstructure throughout the remainder of the tone range.LUX Membrane 200 boosts solid inkdensity (SID) when used to image platesprocessed with solvent or Lava thermalsystemsLUX Membrane 200 reduces print mottlewhen used to image plates processedwith solvent or Lava thermal systems
3White paper l 31 January 2013 I LUX Membrane 200Ink: making the most from the leastThe amount of ink applied to a flexo plate on press is determinedby the volume of the anilox roll, so changes in anilox volume willhave a profound influence on color density. However, for avariety of economic and operational reasons, it is preferable touse the minimum amount of ink required to achieve the neededprint quality. Doing so obviously reduces ink costs, but perhapseven more importantly, it allows crisp reproduction of halftonesand more consistent (i.e. “cleaner”) print runs.However, the amount of ink applied to the plate is only half thestory. The way that the ink is distributed on the surface of thesubstrate plays a major role in its appearance as well. It isduring the ink transfer step that the plate can play a major role inimproving both the solid ink density (SID, the intensity of thecolor) and the uniformity (most commonly measured as mottle)of the ink on the package.The LUX ProcessLUX adds a single step to digital flexo platemaking, using alamination process to cover the digital mask after ablation, priorto UV exposure (see workflow diagram below).The LUX process adds a lamination step to the platemaking workflowLamination of the LUX membrane blocks the effects of oxygenon the photopolymer during UV-induced crosslinking, causingthree major differences compared to standard digitalplatemaking:1. LUX dots have a flat top, but retain the steep shoulderangled of digital dots. This combination of geometric
4White paper l 31 January 2013 I LUX Membrane 200factors gives LUX dots exceptional stability and low dotgain characteristics.2. LUX dots are ‘type high’, meaning that dot tops are thesame height as solids. Press startup is simplifiedbecause all print elements contact the substrate at thesame impression level.3. LUX allows the photopolymer to image 1:1 to the maskimage. There is little or no bump curve, and the maskimage is translated into the photopolymer with a highdegree of fidelity.The print benefits of the LUX dot shape have been provenrepeatedly. This new class of dot shape has become anenabling technology for advanced screening because of theexceptional stability of LUX highlight dots. In addition, the LUXdot shape reduces the impression sensitivity of the plate, givingmore consistent print results throughout a run and from run-to-run with the same plate.Lamination allows surface modificationThe LUX lamination process includes the ability to modify thesurface of the plate by embossing a pattern into the unexposedphotopolymer. This patented LUX capability is unique; no otherflat top dot process can achieve plate surface modificationdirectly.There are two membranes available for LUX – Membranes 100and 200. LUX Membrane 100 is a smooth membrane that givesthe LUX dot structure and 1:1 imaging, with a surface veryBy blocking oxygen and shaping the UVlight, LUX creates dots with flat tops,steep shoulders, and 1:1 fidelity with themask image
5White paper l 31 January 2013 I LUX Membrane 200comparable to standard digital plates. LUX Membrane 200imparts an engineered surface roughness to a digital plate duringthe lamination process, as well as having the same unique LUXdot shape and 1:1 imaging capability.LUX Membrane 200 adds an engineered surface roughness to the plate, along with the high fidelity imaginginherent in the LUX processThe surface texture imparted has a roughness of about 400 nm,very similar to that of MacDermid capped digital plates such asDigital Epic and Digital MCH. In these capped plates, thisroughness frequency had been proven over thousands ofkilometers of printing to deliver improved solid ink density (SID)and reduced mottle, so we targeted this same roughness for ourLUX process as well. The surface pattern is present throughoutthe tone range, improving the ink transfer of both dots and solids.The surface pattern is random, and thus cannot createinterference patterns (e.g. moiré) with any other screeningelements used in the artwork.LUX Membrane 200 adds a randomsurface pattern throughout the tonerange, to both solid and dot surfaces
6White paper l 31 January 2013 I LUX Membrane 200The pattern has proven highly durable too, as it remains visibleon the plate surface even after 100,000+ meter print runs. Thisensures that solid ink density and gain remain consistentthroughout a print job.LUX Membrane 200-treated dots before and after a 579,000 meter print runPrint EffectsOn press, LUX Membrane 200-treated plates deliver significantlyhigher SID and lower Mottle than either standard digital or LUXMembrane 100-treated plates. And this improvement isapparent on both solvent- or thermally-processed plates.Solid Ink Density (SID) is improvedsignificantly by the use of LUXMembrane 200
7White paper l 31 January 2013 I LUX Membrane 200While numbers quantify the effect well, they do not give one a fullappreciation of the impact that the improved print brings.Visually, the effects of Membrane 200 are often quite striking.LUX Membrane 200-treated plates give better ink laydown and color density on white polypropyleneThen benefits of LUX M200 are available on most substratesfrom envelope stock to coated papers to polymeric films.Mottle is decreased significantly by theuse of LUX Membrane 200SID is increased and mottle isdecreased for Digital MAXimaged with LUX Membrane 200(right) compared to Digital MAXimaged in standard digital format(left), both printed on paper.
8White paper l 31 January 2013 I LUX Membrane 200Simplicity is a virtueOne of the nicest things about LUX Membrane 200 is itssimplicity. There is no extensive testing required to find the rightsurface pattern and the digital imager can be run at its maximumthroughput because there is no need for fine details to be etchedinto the solid portions of the mask.ConclusionsLUX and Membrane 200 offer a combination of benefits no otherimaging technique can bring to package printers. The LUX dotshape gives exceptional highlight dot stability, low mechanicalgain, and uniform dot height. LUX Membrane 200 imparts asurface roughness to the plate that is durable, random, andoptimized to increase SID and reduce mottle in print.