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The Search for the Supreme Separation Method

(August 2007) posted on Mon Aug 20, 2007

Explore common color-separation techniques, the ideal situations in which to use each one, and how to combine the methods for optimum results on press.

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By Thomas Trimingham

Why use index separations in your shop? Index printing can maintain detail when you reproduce paintings or illustrations that would otherwise be at risk with traditional halftones. Index printing is a great method for shops where number of colors is less of an issue and ease of printing and separation is more important. Finally, index separations work great for templates where vector designs are laid on top of them or quickly layered into the image files. Name drops can be properly viewed and then quickly printed out using index separations.

Index separations and prints have a unique look and seem complex, but many printers don’t realize just how simple they are to create and print. A couple extra colors are not a very big sacrifice if hours of separation and press setup are saved. However, index seps aren’t perfect. A major downside to index printing is the loss of control on transparencies and long, graduated shadows on designs. Index is a variable square dot, so it can’t recreate fading and transparent effects as well as simulated process can without adding a lot of extra colors.


Combining methods

Deciding on a primary method of separation for your screen-printing shop can be a simple process when the art leads the way. Printers who already feel they have a good handle on a separation method would be well served to investigate the ones that they are not using. Simulated process is a fantastic method, but it is often slow and tedious compared to index separation. On the other hand, index separation by itself can not effectively recreate many images that have shadowy effects. One solution is to learn and merge several of these methods and create an original method that breaks down the barriers of definition.

Use index separations with simulated-process areas incorporated to handle the shadows and transparencies. Use four-color process inks as spot colors with some gradient overlays to help crunch down colors on simple jobs. Try index separations using four-color process inks and simulated spot colors to reproduce difficult images without the worry of frequency problems or dot gain. Concepts like these can separate you from your competition and help you produce fantastic prints consistently and without a lot of downtime.


Thomas Trimingham is an award-winning art director, illustrator, and separator who has more than 16 years of experience in the screen-printing industry. He can be reached at




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