It depends on the plate (though no hair lines, please!). If your plate has a 94 or 95 in the product name, we recommend at least a 0.25 point thickness (or larger). If your plate has 145 or 152 in the product name, we recommend at least a .35 point/.007″ thickness (or larger). Watch out for typefaces with swirly curves that thin or have breaks or fonts with fine cross bars.
For dots, we recommend at least a 1 pt diameter if your plate has a 94 or 95 in the product name. Boost that to 1.25pt diameter for plates that are 145 or 152 in thickness. Each of those dots has to stand on it’s own on the plate and that thickness will provide the support at the base of the plate to hold the dot. Watch out for typefaces where the dots on the “I’s or periods are small, as seen in many sans serif fonts that are decorative, free form or look hand drawn.
Undersize lines and dots may appear on your plate as wavy or be missing completely so checking this is very important for a good file and usable plate.
Posted in: Designing for Letterpress, File Preparation, File Preparation, Unexposed Photopolymer