Mesh-to-LPI Ratio

Mesh-to-LPI ratio is the sanity check between the screen and the separation: multiply the line count by four or five and that's the mesh you need. 45 LPI wants 180-230. 55 LPI wants 230-280. 65 LPI wants 260-330, which in practice means 305. The reason is physical support. At 55 LPI a 10% dot runs roughly 160 microns across, and a 230 mesh has openings near 60 microns, so that dot spans three or four threads and has something to sit on. Drop to 156 mesh and the same dot straddles one or two threads, so it prints ragged or not at all.

For a buyer, the mesh-to-LPI ratio is a fast way to read a quote. If a shop promises 65 LPI photographic detail and the screen rack is all 110s and 156s, the print will not resemble the mockup. Ask what mesh the halftones run on. An answer like "230 for the color channels, 156 for the base" describes a shop doing real simulated process. "Whatever's on the rack" describes a shop guessing.

Working printers pick the line count from the mesh they own and the garment in front of them, not the reverse. Fleece and heather blends have surface texture coarser than a 65 LPI dot anyway, so 45-55 LPI on 230 mesh prints sharper than 65 LPI on a 305 that's starving for ink. Rotate the mesh roughly 22.5 degrees off the screen angles too, because a marginal ratio plus aligned thread weave is where moire gets born.

The belief to drop is that a higher line count always means more detail. Once the mesh-to-LPI ratio falls under about 4:1, raising LPI subtracts detail: highlights break up, shadows plug, and the print ends up coarser and harsher than the 45 LPI version would have been.