It’s all about the screens. Well, who cares about screens? If you purchase color offset printing services, you should be aware of the differences between the 2 different screen technologies used in commercial printing. It affects the quality of all your color prints. You may know some of these things, but most people who buy prints don’t know what you’ll learn in this article. This is a bit technical, but stick with it because you may want to make some changes to the way your print is printed. Then let’s get started.
Is that how it works. Your files go to prepress where they are reviewed for technical errors before being converted to screens for printing; is the first step in the process. The client files then go to a plate maker to be processed and then transferred (offset) onto 4 different metal plates, one each of cyan, magenta, yellow and black. Each plate transfers the ink to a rubber blanket, and the blanket moves the ink onto the paper.
Most commercial printers use conventional AM (amplitude modulated) line screens, which are dots arranged in a rosette pattern to create images. That means each screen plate has to line up perfectly at very high speeds of press cylinder rotation to maintain sharp registration. At typical press speeds, plate alignment can be unstable. The way it works is that some dots are big and some dots are small depending on their tonal value. The larger the dots, the more ink they collect.
The most commonly used line screen dots are 150 to 300 dots per inch, depending on the screens used by the printing company. Printing companies pick one type of screen and use it for all their printing, so you can’t ask your printer to use high dotted line screens. One problem is that conventional displays use a lot of ink that pools. Details are reduced due to too much ink being flooded onto the paper. The color gamut is the range of colors that can be printed. Too much ink inhibits subtle colors and tones are lost because the color gamut is reduced. Subtle colors cannot be printed and moire patterns may appear in textures and patterns. Another problem is banding in color gradations because it is difficult to print smooth transitions of color tones with AM screens.
The other detection method is known as stochastic FM (frequency modulation) (stuh-kas-tick) displays. There are different brands and they all have their own unique proprietary variations. These types of screens are different because FM screens are made with tiny specks similar to the grain in photographs. As an example, I’ll talk about the Kodak Staccato brand displays, which I’m most familiar with.
FM screens use irregular 20 micron specifications to print in color. 1 micron equals 0.000093701 of an inch or 1,000,000 to a yard. A 20 micron screen prints 1,270 specs per inch. These tiny, microscopic specks are ideal for printing high-definition detail in photos, fine art, type, and smooth color gradations.
Stochastic displays offer many advantages over conventional displays. They enhance detail and definition, clean up inverted text impressions. Improved detail in shadows and highlights, plus a wider color gamut so more colors can be printed with conventional line screens. FM screens eliminate unwanted screen angle moiré, subject moiré, and rosettes. The result is a continuous-tone photographic appearance with more color stability over the print run. When color and tonal instability occurs using stochastic displays and misregistration occurs, sharpness and quality are not affected. These are just some of the benefits of FM screens.
Like all print buyers, you want your advertising, sales, marketing and branding promotions to be impressive and attract a lot of attention at an affordable price. You may be surprised to learn that the cost and turnaround times with FM screening technology are probably no more and may be less money than what you are paying for conventional AM screen printing.
The next time your color printing is done, ask your printing company what line screen they use and if they use stochastic screens. Don’t be surprised if you never heard of it. If they can’t, you can buy a higher quality print by finding a company that uses high definition FM stochastic screen printing technology. When excellence is available, good is not enough