The ideal LPI depends on your paper and presswork, but most printers printing on uncoated paper use a 100 LPI. It’s a good balance of fine screen and easy printing. The higher the line screen, the more difficult it will be to print, because the high line-screen plate plugs up with ink in the shadows and looks murky over-all. Some printers prefer playing it safe and order 85 or 65 LPI. Using a lower LPI does make the dots coarser and more obvious. The finest line screen that we usually process is 133 LPI, although we would even question the use of 133 LPI, except on coated or hard papers.
If you’d like a halftone for your image, don’t adjust or apply an LPI in your file. Just tell us what LPI you’d like us to use, and we’ll take care of the rest.
If you tell us the paper, the type of press you’re using, and what you hope to accomplish with your halftone, we would be happy to recommend a line screen for you!