Learn how to do a basic spot color separation inside Photoshop for outputting film positives for screen printing t-shirts.
Color Separations in Photoshop - Channel Separations
- Go to Select < Color Range to begin selecting your first color. The Eye Dropper Tool will pop up with a dialog box with a slider. Using the Fuzziness Slider you can select more or less of a particular color hue. After you have the amount of color you would like to pull/separate- select the invert box.
- At the bottom of the Channels Panel is a small icon, a rectangle with a circle in the middle, click that and your color is now Saved as a New Channel.
- Double click your new channel and change it from an Alpha Channel to a Spot Color Channel. In the color box at the bottom of the pop up window you can change the color of the channel to your sampled color you selected. Change the opacity of all colors to 5%. A White Underbase channel should be set to an opacity of 85% - 90%.
- Follow all the above steps to "pull" each color in your design to it's own spot color channel.
- When you have all the colors separated your ready to print out of Photoshop. In the pop up print dialog box select separations instead of letting the printer or Photoshop manage colors. I recommend using a RIP (raster image processor) to print halftones. Your halftones can range from 35lpi to 65 lpi. Halftones are another factor to take into consideration- a 35lpi can give your print a completely different look then a 55lpi print will.
Spot color separation in Photoshop can be done a couple different ways. One way is to separate each color to it's own layer in Photoshop and print your film positives. This is a very simple and "crude" way to create your film positives for screen printing. But hey- when your in a pinch it can work so you can get the job done. When you use this method just make sure to lay black color over the layer be fore you print each layer as a "separation".