To get started, open Photoshop and go to Window>Application Frame to set up your canvas (you’ll need this for the next step). Your job will be easier if you either have an image with a limited number of colors, or you alter some colors to limit the total number of colors. When you’re working with existing artwork in Photoshop and you don’t have layers, you have to manually create the separations by selecting each main color and creating spot color channels. Notice that some of the design is missing on the gold color artwork where the green text will print. When you look at the separated artwork, whatever is being printed at 100% appears black while anything using less ink (to create a lighter color) appears in shades of gray. A two-color logo, in this example green and gold, requires two separations: one for each color. Although talking to a T-shirt screen-printing company for advice is always a good idea, here are the basics of making spot-color separations.īefore we go into a detailed description of creating separations in Photoshop, here’s a quick primer. The best way to figure out the best way is to know all the ways.You’ve made a great design for a client and now they need it printed on T-shirts-and they have asked you for separations. There are many other ways to do separations and I would urge anyone reading this to seek out more information and choose the way the suits you best. The information is not for beginners, but if you would like more information or explanation, you can email me and I will try to answer your questions. If you get the concept, then the best way to explain it is to just show you what I did, hence all of the big pictures. I knew I would print the colors in the order red - gray - black and I did the separations for that order. On the Misfits poster, there’s a good bit of outlining done by hand, but I take any shortcut I can whenever I can. You can see on the detail above that there were a few areas that I had to draw the color in by hand, using the pencil tool, but most of it I was able to just Expand and Fill. I do the color separations in color at first and then fill them with black to print the layers on transparencies, since you need good solid black art to burn the screen. Once I had the areas selected I went to the Select menu and used the Modify > Expand to make the selection larger and then filled the area with color on a new layer (Edit > Fill).
To do the seps for this Viking Kings poster, I just selected the open areas with the Magic Wand Tool in Photoshop, with anti aliasing turned off (unchecked). You can see some of the mistakes I made in the inking.
Here’s a scan of some line art before it was touched up. If you are printing the seps out on an inkjet printer like we do, it doesn't matter much. I do the separations in either RGB or CMYK mode. Keeping the edge non-anti aliased makes selecting the lines easy and doing the separations easy and accurate. Once the art is totally black and white with no grays I touch up the art with the pencil tool to keep the hard edge on the art. If the line art is too light I will use the Brightness/Contrast adjustment to darken the lines before I use the Threshold adjustment. I scan it in Grayscale, import it into Photoshop and use Image > Adjustments > Threshold to change the image to a bitmap and eliminate the anti-aliasing that makes the lines fuzzy, playing with the setting to get the line weight I want. If the art is closer to the final size I might use 400 pixels/inch. I have a pretty tight drawing style so I sometimes draw the art smaller than the finished print size and scan it at 600 pixels/inch. The resolution depends on what size I drew the art. Once the art is finished and the pencil lines erased, I scan it at a pretty high resolution in Black & White Grayscale mode. I'm not trying to produce an original masterpiece, just a good final product and fast is better. If I make a mistake, I usually draw the correction right through the mistake and fix the line art in Photoshop. Both the regular markers and the brush markers. In case you are wondering, I sketch the drawing and transfer my sketch to Graphics 360 Marker paper with a mechanical pencil, tightening the sketch as I transfer it, and then ink it with markers, mostly Pigma Micron. Still have a bunch of Rubylith in a box somewhere. I’ll give up my Adobe Photoshop when they pry it from my cold, dead fingers.
Of course, you can do color separations by hand and cut the film, but I did that for way too many years before we had computers. Here are a few examples of how I do color separations for silk screened posters in Photoshop. Note: The information here is for people with some familiarity with screen printing and computer graphics, specifically Adobe Photoshop.