So you’ve come up with a brilliant idea for a POP display, you’ve had designers like ours at Ardent perfect the structure so it showcases your product beautifully, you’ve chosen graphics that reinforce your marketing message and make everyone in your target demographic want to purchase your product. Now you have to make the big choice: what printing process should you use to get the best results for your display?
For commercial printing, you have many options, including lithography (also called offset printing or litho printing), flexo printing, and digital printing. Below is a primer on offset lithography, so you know when to choose litho and why.
According to our creative director, aptly named Art, there’s one main rule to keep in mind with print choices: “If you have a photograph, you better use litho.”
Lithography is the process that will best achieve photorealistic results in printing, holding to the true color and shading in your images. Although a more complex and expensive process, it’s worth it if you need to maintain the integrity of gradients, shadows, and other graphic subtleties.
Lithography is typically a 4-color process that begins with creating a printing plate of your image. Modern printing plates are most often made of a flexible aluminum and then covered with a photosensitive liquid. A negative of your image is placed against the liquid and exposed to UV light, creating a replica of your original image. A different plate is made for each printing color– cyan, magenta, yellow, and black.
Now, the metal plates with your image are attached to cylinders on a printing press, each color coming one after the other. Let’s say first up is your yellow plate. The cylinder with your plate on it is attached to a mechanism where rollers add water to the blank parts of the plate. The image on your plate is made with chemicals that repel water, so the water just sticks to the negative space. Next, inking rollers apply hydrophobic yellow ink to the image. Hydrophobic literally means “afraid of water,” so this ink only sticks to the positive space on your image.
Once the ink is applied to it, your plate rolls against a blanket cylinder. This cylinder has a rubber blanket on it that removes the water and evenly spreads out the ink. The paper or SBS you’re printing on slides in between the blanket cylinder and what’s called an impression cylinder. As it moves through the two cylinders, the image is transferred from the rubber blanket to your paper. What comes out is all of the yellow tones in your image. The paper will now continue to slide through the next blanket cylinder, let’s say this one is your cyan cylinder, and repeat the same process. Once it’s gone through all four colors, you will have a complete, full-color image! Of course, if you are very particular about your color, you can even add 5th and 6th colors. For example, if your company has a signature color–maybe a nice bright pumpkin–that dominates much of your graphics, and it’s important that it’s perfectly matched in every print, you can add another print plate and set of cylinders to the lithography process. You can also add varnishes to protect your images from scratches and add different effects, like a glossy sheen or flat matte look.
This is a difficult process to visualize. Below is an drawing of a set of cylinders–imagine your printed image going through four or more of these, sort of like an assembly line, picking up a new color each time.
(Image borrowed from http://www.ctitech.com/images/lithography.gif)