How to prevent Moire

Moire: How to prevent Moire from appearing in your print especially your textile base plates.

                                                                         Moire is the interference of halftones and mesh. This interference is the result of mesh or mesh knuckles blocking some or part of the halftones in an image. Generally moire is controlled by placing halftones on a specific angle when creating film via a RIP program and having four or more mesh open areas per half tone dot.

                                                                           This example shows no moire since the mesh (shown in red) has at least 4 threads or mesh open areas per halftone dot resulting in no blockage of the halftone print. This formula of multiplying halftone line count by 4 or 4.5 yields good results providing we output the film with the halftone on a specific angle. Not all angles work at preventing moire. We have included charts in this article to show what angle works for various Smartmesh thread counts.

The math above works fine for graphics where printing with high mesh counts is the norm, but what about printing halftone base plates for textile? White textile base plate ink on 250 to 300 mesh simply won’t print well. So how can you print bright white base plates with good halftones and no moire? S-thread mesh answers this question and also prints base plates much better than conventional T thread mesh.

S-thread mesh with it’s larger open area can use 45 and 55 line count halftones and produce incredibly bright halftone base plates using mesh counts lower than the mesh count achieved by multiplying by 4 or 4.5. These combinations of mesh and angle work!

Bright Halftone Base Plates Notice the use of the word ‘bright’. Too often printers settle for a halftone base plate for simulated process or index printing that is anything but bright. We thin the white base plate ink with viscosity reducers, halftone base, softeners, all in an attempt to get it to print well through a fine mesh due to the math described on the previous page. A bright white base plate simply allows the printer to massage the overlying colors by increasing transparency to obtain secondary and tertiary colors that develop as the overlay colors mix during print. Without a bright base plate the image is muted, or needs to have overlay colors be as opaque as possible to keep color intensity in the design. However many subtle color transitions are lost as either opacity of overlay colors blocks the color transitions, or the thinned base plate lowers the color quality of the transparent overlay colors.

The Solution? S-thread or the new LX Mesh from Smartmesh sold by Murakami is the answer in achieving brighter base plates. Both have a higher percentage of open area than typical mesh and allow the printer to lay down an opaque base plate with unmodified inks right out of the container. No need to lower the opacity of your white base plate ink, just switch to a better mesh. S mesh and LX Mesh sold by Murakami USA allows the ink to be printed on the surface of the shirt. The squeegee needs less pressure to print the thick base plate ink. This results in less dot gain and more opacity in the base plate and achieves more vibrant prints. Secondary and tertiary colors can improve since the overlaying colors can be thinned with transparent base to mix well during the wet onto wet print process typical of index and sim process style. Click here to continue reading the article: How to Prevent Moire

For more information and specifications on using Murakami products in production please contact our Technical Support Representatives available Monday through Friday 8am to 5pm PST at: (323) 980-0662