It’s all about the screens. Well, who cares about screens? If you buy 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 buying prints don’t know what you’ll learn from 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 are sent to prepress where they are reviewed for technical errors before turning them into screens for printing; It is the first step in the process. Customer files then go to a plate maker to be processed and then transferred (offset) to 4 different metal plates, one cyan, magenta, yellow and black. Each plate transfers the ink to a rubber blanket and the blanket displaces the ink on the paper.
Most commercial printers use conventional AM (amplitude modulated) line screens, which are dots arranged in a rosette shape, to create images. That means each screen plate has to be perfectly aligned at very high speeds of press cylinder rotations to keep the registration sharp. At typical press running speed, plate alignment can be unstable. The way it works is that some dots are large and some dots are small depending on their tonal value. The larger the dots, the more ink they collect.
The most commonly used screen dots are 150 to 300 dots per inch, depending on the screens used by the printing company. Printing companies choose one type of screen and use it for all their printing, so you can’t ask your printer to use high-dot line screens. One problem is that conventional screens use a lot of ink that builds up. Details are reduced due to the paper being flooded with too much ink. 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 moiré patterns may appear in textures and patterns. Another problem is banding in color gradations because it is difficult to print smooth color tone transitions with AM displays.
The other screening method is known as stochastic FM (frequency modulated) (stuh-kas-tic) screens. 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 small, grain-like spots in photographs. As an example, I will talk about the Kodak Staccato brand displays, which I am most familiar with.
FM displays use irregular 20 micron specifications for color printing. 1 micron equals 0.000093701 of an inch or 1,000,000 to a yard. A 20-micron screen prints 1,270 specifications per inch. These tiny microscopic spots are ideal for printing high definition detail in photographs, artwork, typography and smooth color gradations.
Stochastic screens offer many advantages over conventional screens. They improve detail and definition, inverted text prints cleaner. They enhance the detail of shadows and highlights, as well as a wider color gamut so that more colors can be printed using conventional line screens. FM displays eliminate screen angle moiré, moiré, and unwanted rosettes. The result is a continuous-tone appearance similar to photography with more color stability during the run. When tonal and color instability occurs using stochastic screens and misregistration occurs, sharpness and quality are not affected. These are just a few of the benefits of FM displays.
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 might be surprised to learn that the cost and response times with FM screening technology are probably not higher and may be less than what you are paying for conventional AM screen printing.
The next time you order color printing, ask your printing company which screen they use and if they use stochastic screens. Don’t be surprised if you have 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 print screen technology. When excellence is available, good is not enough
