People often ask me how much detail they can expect to see with letterpress. You can always achieve a great amount of detail with your ink, but if you’d like a lot of impression in your piece you should allow some space between your lines. Too much crowding won’t allow the plate to sink into the paper very well. Unless of course you use an extremely soft paper, like a 100% cotton art paper.
Here is a direction card that is part of an invitation set I printed this past weekend. It’s a nice balance of tiny lines with enough space between.