Gradients require a little thinking about when screen printing. Moire patterns are tricky to avoid, many printers have their own rule of thumb calculations to decide on meshes, the most common are 3.5 or 4 X your halftone LPI = the mesh count you should use (imperial). The angle of the dot on the screen is also a big factor in avoiding moire patterns.

But none of these calculations really allow for a mesh below 196/77T, when screening water based inks by hand these fine meshes can make life very difficult. So can you put a 55lpi half tone on say a 34T and get a satisfactory result?

We think yes, in some cases it is ok. if you need to apply a large area of ink with a fade we think a coarse screen can do the job very well, the problem of moire is in fact reduced. However there is the problem of  losing the finer dots on a coarse mesh, and this will reduce the tonal range.

This coarse mesh is not able to hold the very small pieces of remaining screen coat causing holes in some places,

at the other end there are less problems in the quality of the half tone, some very fine pin holes may sit on top of the wide mesh fibre and will not wash out, but the finished printed gradient does not suffer. The reason for this being it is a gradual change in colour over a large area, using only 2 colours. We would not like to attempt a full process colour job using such coarse mesh, but then we would probaly not print a full colour process screen print hand.

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Related posts:

1. Coarse screens and half tones
2. Simulated process separation printed with waterbased ink
3. 5 colour index separation and waterbased ink
4. Halftone Dots and Screenprinting
5. Silk Screen Stencils