Preparing a color separation for screen printing can be an involved process. We can break the process into several distinct stages, however, to make a manageable workflow. I cover each step in some detail here on this site, but for this post I want to tie them all together. While each stage can have it’s own series of steps, here I will outline the main parts, while including links to detailed explanations.
• Preparing the image – File preparation
This first step is easy to overlook, but careful attention at this stage can make the entire process easier while improving the results dramatically.
There are three main parts to this step:
1. Setting the images Black and White points
2. Cleaning up the image
3. Removing the background
• Creating a Base Separation – The YRGBK Script
Although many color separators will jump right in and start building a color separation from the prepared image, I have found it is helpful to start with a base separation generated using a standard process. There are several advantages I find with this approach.
First, a decent color separation algorithm can get you a good ways down the road towards a finished product, while a great one can get you pretty close to the finish line, depending on your needs. Elements like a Base white, HIghlight White and Black channels can be created consistently from project to project, while color channels can be generated in a way that ensures all color information is present.
Finally, it can be helpful to leverage the knowledge of an experienced color separator when using an scripted algorithm or technique for this process. The YRGBK Script was developed for this purpose.
• Customizing the Separation.
The best results are obtained when a color separation is designed to accommodate not only the image, but also the printing technique and substrate it is being printed on. Whether it is splitting solid colors from halftones for textile printing, or converting primary colors to Custom colors for color matching and ink coverage, the results are always worth the effort.
• Clean up and review.
Once the separation is complete it is good to have a review process and clean up stage. I like to make this a defined part of the process so I do not get bogged down in clean up while I am trying to customize a separation. It is also helpful to ensure the image has been cleaned up and to take a final look at how the colors are going to print. Stray 1% dots, 98% solids that should be 100%, and misplaced custom colors can all be handled easily at this point, while providing potential headaches if they make it on to the press.
• Convert the gray values to printable dots – SimRip 3
Since a color separation is generated using gray values in our channels, it is necessary to convert these values to printable dots which can be imaged on the screen or plate. Dot Size, Shape and Angle all play a part in not only the look and feel of the print but also in the quality of the result.
Whether I am printing to the Direct to Screen printer at the shop, or making film in my art studio, I have found significant benefits to handling this conversion within Adobe Photoshop. Even though I may be printing to an actual Rip, which traditionally handles this step, the flexibility and control as well as the ability to carefully review the output has led me to converting every job to halftones within Adobe Photoshop.
• Output the Color separation to film, plates or screens.
Finally, with the separation complete and converted to halftones, the channels are sent to the printer.