Understanding how to prep files for screen printing on paper can be a bit tricky, which is why I recommend going over the following information several times. Please download either the Photoshop or Illustrator file as they are setup specifically for screen printing on paper. Also feel free to call once you have downloaded as I am more than willing to walk through all of this so you feel confident moving forward doing it correct from the start. (303) 321-7101, ask for Stu
PLEASE NOTE: the following info is for screen printing on paper – for screen printing on fabric, please consult your local t-shirt printer.
Review File Specs
There will always be exceptions to the following, but this is a good place to start for file setup on paper.
File Type: Illustrator AI or Photoshop PSD.
File DPI: if it is not a vector image, it needs to be 300dpi at 100% printing size.
File Dimensions: file dimensions should be the same size as the final print with one exception. If you have ink going to the edge, then you must add .125" to all 4 sides and anywhere the ink goes to the edge, it too must extend .125". In printing this is referred to as a "bleed".
Color Space: design in CMYK to give a more accurate visual idea of how inks will print - RGB has colors that don't exist in inks.
Color Swatches: all swatches should be set as global CMYK swatches when working in Illustrator. Here's a link to help If you are unfamiliar with Illustrator settings. When using a physical Pantone swatch book to pick ink colors, select from the Uncoated book.
Color Density: all colors must be 100% density of the ink color.
Halftones: as a good starting point – when converting to a bitmap, at 300dpi use 30-35lpi. It is also good to over emphasis the contrast as from about 85-99% density tends to fill in and print solid, where 1-15% density may not expose and can disappear.
Line Thickness: for dark lines over light colors, lines should be at least 1pt in thickness. In Photoshop, at 300dpi, 1pt = around 4-5 pixels. For light colored lines reversed out of large solids, I recommended making lines closer to 2pts (8-10 pixels) as they can fill in when surrounded by large amounts of ink.
Layers: every ink color must be on it's own layer and ideally each layer should also be labeled with the color of the ink.
Knockout: shapes need to be knocked out of colors to allow the paper or ink to show through from below.
Trapping: this is the relationship created when 2 colors touch where there are several ways to create the trap. When a color is 100% surrounded, generally you can simply add a 3-5pt stroke. It becomes more tricky when colors go between other colors.
Overprint: when you have darker ink colors printing over patterns or small areas of lighter colors, you will generally overprint the dark inks instead of trap.
Registration Marks: please do not add as I have a specific template setup.
Guides: please do use as they will help make sure your margins are equal.
The above file is available to download (see below) as either a Photoshop PSD file or Illustrator AI file to help you better understand the relationships between colors when screen printing on paper. Please take some time to investigate the intersecting relationships of ink colors to understand the differences. For issues not addressed, such as printing on dark papers, gradients or percentages of colors, printing photos, etc. – please call to discuss further setup.
Click on image to download.
Click on image to download.